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Lesson 1: Types of RNA, Genetic Code and Protein Translation/
Interactive Exam & Question Bank (300 MCQs)
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Full Exam & Question Bank: Lesson 1: Types of RNA, Genetic Code and Protein Translation
300 standard ministerial MCQs measuring key competencies with step-by-step navigation and organized palette.
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Question 1 of 227
Official Ministerial Exam Question • High-Order Thinking
The stop codons that signal termination of translation on an mRNA molecule include:
A
AUG, UAA, UGA
B
UAC, UGG, UAA
C
UAA, UAG, UGA
D
GUA, CAU, UAG
Question 2 of 227
Official Ministerial Exam Question • High-Order Thinking
If a double-stranded DNA sample contains 28% Adenine, what is the exact percentage of Cytosine in this sample?
A
22%
B
28%
C
56%
D
44%
Question 3 of 227
Official Ministerial Exam Question • High-Order Thinking
Which enzyme is responsible for linking Okazaki fragments into a continuous strand during lagging strand replication?
A
DNA Polymerase
B
Reverse Transcriptase
C
DNA Ligase
D
DNA Helicase
Question 4 of 227
Official Ministerial Exam Question • High-Order Thinking
What is the structural characteristic of a restriction endonuclease recognition site?
A
It consists of 15-20 repetitive nucleotides.
B
It contains only adenine and thymine bases.
C
It is a palindromic sequence reading identical 5' to 3' on both strands.
D
It always begins with the start codon AUG.
Question 5 of 227
Official Ministerial Exam Question • High-Order Thinking
Why is the genetic code described as 'degenerate' or 'redundant'?
A
One codon can code for multiple different amino acids.
B
The genetic code differs completely between bacteria and humans.
C
The genetic code decays as the cell ages.
D
Multiple different codons can code for the same single amino acid.
Question 6 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following first-row transition metal ions exhibits the highest theoretical magnetic moment in its ground state?
A
Cr3+ ([Ar] 3d3 with 3 unpaired electrons)
B
Zn2+ ([Ar] 3d10 with 0 unpaired electrons)
C
Cu2+ ([Ar] 3d9 with 1 unpaired electron)
D
Fe3+ ([Ar] 3d5 with 5 unpaired electrons)
Question 7 of 227
Official Ministerial Exam Question • High-Order Thinking
The main chemical reducing agent inside the Midrex furnace and its industrial source are respectively:
A
Carbon dioxide mixed with limestone
B
Water gas (mixture of CO and H2) produced from natural gas (methane CH4)
C
Pure carbon monoxide (CO) produced from metallurgical coke
D
Hydrogen gas produced from the electrolysis of water
Question 8 of 227
Official Ministerial Exam Question • High-Order Thinking
A transition element whose +5 oxidation state compound (V2O5) is widely utilized as an industrial catalyst in the Contact Process for sulfuric acid manufacturing and as a colorant in ceramics is:
A
Scandium (21Sc)
B
Cobalt (27Co)
C
Manganese (25Mn)
D
Vanadium (23V)
Question 9 of 227
Official Ministerial Exam Question • High-Order Thinking
When dry chlorine gas is passed over red-hot iron filings, iron(III) chloride (FeCl3) is exclusively formed rather than iron(II) chloride because:
A
Iron(II) chloride spontaneously sublimes into thin air
B
The reaction occurs strictly in an alkaline medium
C
Chlorine gas is a powerful oxidizing agent that readily oxidizes any formed Fe2+ to Fe3+
D
Chlorine cannot react with the inner 3d electrons
Question 10 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following alloys is classified as an interstitial alloy?
A
Carbon steel (Iron and Carbon where small carbon atoms occupy interstitial voids)
B
Stainless steel (Iron, Chromium, and Nickel)
C
Duralumin (Aluminum and Copper)
D
Brass (Copper and Zinc)
Question 11 of 227
Official Ministerial Exam Question • High-Order Thinking
The electronic configurations of both Chromium (24Cr) and Copper (29Cu) are anomalous due to the enhanced stability associated with:
A
Half-filled (3d5) and completely filled (3d10) d-subshells respectively
B
Pairing of all electrons in the outer valence level
C
High electronegativity differences
D
Completely empty 4s subshells
Question 12 of 227
Official Ministerial Exam Question • High-Order Thinking
Concentrated nitric acid (HNO3) induces chemical passivity on the surface of iron metal due to:
A
The precipitation of elemental sulfur on the surface
B
The instantaneous dissolution of iron into gaseous ions
C
The formation of an extremely thin, non-porous protective oxide film that halts further reaction
D
Complete neutralization of the acid
Question 13 of 227
Official Ministerial Exam Question • High-Order Thinking
The atomic radii of the elements from Chromium to Copper remain remarkably steady and nearly constant across the first transition series because of:
A
The mutual compensation between the increasing nuclear charge and the repulsive forces among accumulated 3d electrons
B
Decreasing ionization energies
C
The identical number of neutrons in their nuclei
D
The sudden increase in atomic mass
Question 14 of 227
Official Ministerial Exam Question • High-Order Thinking
Magnetic iron oxide (Magnetite, Fe3O4) is chemically considered a mixed oxide because reacting it with hot concentrated sulfuric acid yields:
A
Elemental iron and sulfur dioxide
B
A mixture of iron(II) sulfate, iron(III) sulfate, and water vapor
C
Iron(II) sulfate and hydrogen gas only
D
Iron(III) sulfate only
Question 15 of 227
Official Ministerial Exam Question • High-Order Thinking
An aqueous solution of titanium(IV) chloride (TiCl4) is diamagnetic and colorless because:
A
It absorbs all visible wavelengths of light
B
Chlorine ions quench all magnetic dipoles
C
Titanium is an alkali earth metal
D
The Ti4+ ion has an electronic configuration of [Ar] 3d0, devoid of unpaired d-electrons
Question 16 of 227
Official Ministerial Exam Question • High-Order Thinking
When dilute hydrochloric acid is added to a solid salt, a gas is evolved with a pungent odor that turns acidified potassium dichromate paper green while a colloidal yellow precipitate of sulfur separates in the reaction vessel. The anion is:
A
Sulfide (S^2-)
B
Sulfate (SO4^2-)
C
Thiosulfate (S2O3^2-)
D
Sulfite (SO3^2-)
Question 17 of 227
Official Ministerial Exam Question • High-Order Thinking
To distinguish between a white precipitate of barium sulfate (BaSO4) and a white precipitate of barium phosphate (Ba3(PO4)2), one should add:
A
Dilute hydrochloric acid (Ba3(PO4)2 dissolves while BaSO4 remains insoluble)
B
Boiling distilled water
C
Concentrated nitric acid in the dark
D
Ammonium hydroxide solution
Question 18 of 227
Official Ministerial Exam Question • High-Order Thinking
A metal cation that forms a gelatinous white precipitate with NaOH which completely redissolves in excess reagent to form a soluble clear solution is:
A
Fe3+
B
Ca2+
C
Al3+ (due to the formation of soluble sodium meta-aluminate NaAlO2)
D
Fe2+
Question 19 of 227
Official Ministerial Exam Question • High-Order Thinking
In a titration experiment, 20.0 mL of 0.15 M H2SO4 is completely neutralized by 30.0 mL of NaOH solution. The molar concentration of the NaOH solution is:
A
0.20 M
B
0.10 M
C
0.30 M
D
0.05 M
Question 20 of 227
Official Ministerial Exam Question • High-Order Thinking
The indicator that exhibits a yellow color in acidic medium, blue in alkaline medium, and green in neutral medium is:
A
Litmus solution
B
Bromothymol blue
C
Methyl orange
D
Phenolphthalein
Question 21 of 227
Official Ministerial Exam Question • High-Order Thinking
A person who skillfully makes beautiful objects by hand is called a/an ________.
A
pilot
B
scientist
C
artisan
D
engineer
Question 22 of 227
Official Ministerial Exam Question • High-Order Thinking
While the students ________ in the art workshop, the tour guide arrived.
A
worked
B
work
C
were working
D
are working
Question 23 of 227
Official Ministerial Exam Question • High-Order Thinking
We visited the pottery village in Fustat ________ our holiday in Cairo.
A
when
B
as
C
during
D
while
Question 24 of 227
Official Ministerial Exam Question • High-Order Thinking
Potters use high-temperature ovens called ________ to bake and harden clay vessels.
A
looms
B
fridges
C
kilns
D
blenders
Question 25 of 227
Official Ministerial Exam Question • High-Order Thinking
Electric buses and monorails produce zero exhaust fumes, making them ________ forms of transport.
A
polluting
B
dangerous
C
noisy
D
eco-friendly
Question 26 of 227
Official Ministerial Exam Question • High-Order Thinking
Watch out! The ladder is shaking violently. You ________ fall!
A
are going to
B
have
C
will
D
were
Question 27 of 227
Official Ministerial Exam Question • High-Order Thinking
I have already booked the flight tickets. I ________ to London next Friday.
A
will travel
B
traveled
C
am traveling
D
travel
Question 28 of 227
Official Ministerial Exam Question • High-Order Thinking
The Cairo Monorail travels on an elevated single-beam track to avoid urban traffic ________.
A
congestion
B
stations
C
gardens
D
comfort
Question 29 of 227
Official Ministerial Exam Question • High-Order Thinking
The n-th term of an arithmetic sequence with first term a and common difference d is given by:
A
T_n = a + n * d
B
T_n = 1/2 n (2a + d)
C
T_n = a * r^(n - 1)
D
T_n = a + (n - 1) * d
Question 30 of 227
Official Ministerial Exam Question • High-Order Thinking
In the arithmetic sequence (3, 7, 11, 15, ...), the common difference d and the 20th term (T_20) are respectively:
A
d = 4 and T_20 = 79
B
d = 5 and T_20 = 98
C
d = 3 and T_20 = 60
D
d = 4 and T_20 = 83
Question 31 of 227
Official Ministerial Exam Question • High-Order Thinking
The sum of the first n terms of an arithmetic sequence (S_n) is formulated as:
A
S_n = n / 2 * [ 2a + (n - 1) * d ] = n / 2 * [ a + l ]
B
S_n = a * (1 - r^n) / (1 - r)
C
S_n = n * (a + d)
D
S_n = a / (1 - r)
Question 32 of 227
Official Ministerial Exam Question • High-Order Thinking
The common ratio r of the geometric sequence (64, 32, 16, 8, ...) is:
A
r = 1/2
B
r = -1/2
C
r = 4
D
r = 2
Question 33 of 227
Official Ministerial Exam Question • High-Order Thinking
The sum to infinity (S_infinity) of a geometric series exists and converges if and only if the common ratio satisfies:
A
r = 1
B
r > 1
C
|r| < 1 (i.e. -1 < r < 1), and S_infinity = a / (1 - r)
D
|r| >= 2
Question 34 of 227
Official Ministerial Exam Question • High-Order Thinking
The sum to infinity of the geometric series 12 + 6 + 3 + 1.5 + ... equals:
A
18
B
36
C
Infinity
D
24
Question 35 of 227
Official Ministerial Exam Question • High-Order Thinking
If a, b, c form an arithmetic sequence, then the arithmetic mean b equals:
A
b = a + c
B
b = (a + c) / 2
C
b = sqrt(a * c)
D
b = 2 a c / (a + c)
Question 36 of 227
Official Ministerial Exam Question • High-Order Thinking
If a, b, c form a geometric sequence of positive real numbers, the geometric mean b equals:
A
b = + sqrt(a * c)
B
b = a * c
C
b = (a + c) / 2
D
b = a^2 + c^2
Question 37 of 227
Official Ministerial Exam Question • High-Order Thinking
The sum of the first 10 terms of the geometric sequence 2, 6, 18, 54, ... equals:
A
118,096
B
29,524
C
59,048
D
19,682
Question 38 of 227
Official Ministerial Exam Question • High-Order Thinking
The number of terms in the finite arithmetic sequence (5, 9, 13, ..., 81) is:
A
21 terms
B
19 terms
C
20 terms
D
25 terms
Question 39 of 227
Official Ministerial Exam Question • High-Order Thinking
The 7th term of the geometric sequence (2, 6, 18, ...) is:
A
486
B
729
C
162
D
1458
Question 40 of 227
Official Ministerial Exam Question • High-Order Thinking
If (x - 1, x + 2, 3x) form a geometric sequence, the positive value of x is:
A
2
B
6
C
3
D
4
Question 41 of 227
Official Ministerial Exam Question • High-Order Thinking
The sum to infinity of the geometric series 16 + 8 + 4 + 2 + ... equals:
A
32
B
30
C
24
D
64
Question 42 of 227
Official Ministerial Exam Question • High-Order Thinking
The derivative of f(x) = 4 x^3 - 5 x^2 + 7 x - 9 with respect to x is:
A
f'(x) = 12 x^3 - 10 x^2 + 7
B
f'(x) = 4 x^2 - 5 x + 7
C
f'(x) = 12 x^2 - 10 x
D
f'(x) = 12 x^2 - 10 x + 7
Question 43 of 227
Official Ministerial Exam Question • High-Order Thinking
The slope of the tangent line to the curve y = x^2 - 6 x + 5 at the point (4, -3) equals:
A
m = -3
B
m = 2
C
m = -2
D
m = 8
Question 44 of 227
Official Ministerial Exam Question • High-Order Thinking
If y = (2x + 1) * (3x - 4), then dy/dx evaluated at x = 1 equals:
A
-5
B
7
C
1
D
12
Question 45 of 227
Official Ministerial Exam Question • High-Order Thinking
Using the Quotient Rule, the derivative of y = (x + 3) / (x - 2) for x != 2 is:
A
1 / (x - 2)^2
B
5 / (x - 2)^2
C
-5 / (x - 2)^2
D
(2x + 1) / (x - 2)^2
Question 46 of 227
Official Ministerial Exam Question • High-Order Thinking
According to the Chain Rule, if y = (3 x^2 - 5)^4, then dy/dx is:
A
4 (3 x^2 - 5)^3
B
12 x (3 x^2 - 5)^4
C
6 x (3 x^2 - 5)^3
D
24 x (3 x^2 - 5)^3
Question 47 of 227
Official Ministerial Exam Question • High-Order Thinking
The derivative of y = sin(3x) with respect to x is:
A
-3 cos(3x)
B
3 cos(3x)
C
3 sin(3x)
D
cos(3x)
Question 48 of 227
Official Ministerial Exam Question • High-Order Thinking
If a particle moves along a straight line such that its position s(t) = t^3 - 6 t^2 + 9 t meters, the particle comes to an instantaneous rest (velocity v(t) = 0) at times:
A
t = 0 seconds only
B
t = 6 seconds
C
t = 2 seconds and t = 4 seconds
D
t = 1 second and t = 3 seconds
Question 49 of 227
Official Ministerial Exam Question • High-Order Thinking
The equation of the tangent line to the curve y = x^3 at the point (1, 1) is:
A
y = x
B
y = 3x - 2
C
y = 3x + 1
D
y = -3x + 4
Question 50 of 227
Official Ministerial Exam Question • High-Order Thinking
The second derivative d^2y/dx^2 of the function y = x^4 - 2 x^3 + 5 is:
A
12 x^2 - 12 x
B
4 x^3 - 6 x^2
C
24 x - 12
D
12 x^2 - 6 x
Question 51 of 227
Official Ministerial Exam Question • High-Order Thinking
If f(x) = |x - 3|, the derivative f'(3) at x = 3:
A
Equals 1
B
Equals -1
C
Does not exist because the left-hand derivative (-1) does not equal the right-hand derivative (+1)
D
Equals 0
Question 52 of 227
Official Ministerial Exam Question • High-Order Thinking
If y = sin(3x) + cos(2x), then dy/dx at x = 0 equals:
A
3
B
1
C
5
D
-2
Question 53 of 227
Official Ministerial Exam Question • High-Order Thinking
The slope of the tangent to the curve y = (x + 1)/(x - 1) at x = 2 is:
A
-2
B
3
C
-1
D
2
Question 54 of 227
Official Ministerial Exam Question • High-Order Thinking
If the tangent to y = x^2 - 4x + 5 is parallel to the x-axis, the point of tangency is:
A
(2, 0)
B
(2, 1)
C
(4, 5)
D
(0, 5)
Question 55 of 227
Official Ministerial Exam Question • High-Order Thinking
The hydrostatic pressure exerted by a static homogeneous liquid of density rho at depth h beneath its free surface is expressed by:
A
P = rho * h / g
B
P = 1/2 rho * g * h^2
C
P = rho * g / h
D
P = rho * g * h
Question 56 of 227
Official Ministerial Exam Question • High-Order Thinking
A diver descends to a depth of 30 meters in seawater (density = 1030 kg/m^3). If atmospheric pressure is 1.013 x 10^5 Pa and g = 9.8 m/s^2, the total absolute pressure experienced by the diver is approximately:
A
4.04 x 10^5 Pa (approx. 4.0 atmospheres)
B
6.06 x 10^5 Pa
C
1.01 x 10^5 Pa
D
3.03 x 10^5 Pa
Question 57 of 227
Official Ministerial Exam Question • High-Order Thinking
Pascal's principle states that when pressure is applied to an enclosed, incompressible fluid, it is transmitted:
A
Undiminished to every portion of the fluid and to the walls of the containing vessel
B
Only downwards towards the bottom of the vessel
C
With an exponential decay as distance increases
D
Strictly to compressible gases
Question 58 of 227
Official Ministerial Exam Question • High-Order Thinking
In a hydraulic press, the ratio of the cross-sectional area of the large piston to that of the small piston is 50. If a force of 100 N is exerted on the small piston, the maximum force exerted by the large piston is:
A
2500 N
B
50,000 N
C
5000 N
D
2 N
Question 59 of 227
Official Ministerial Exam Question • High-Order Thinking
The mechanical advantage (eta) of an ideal hydraulic press equals all of the following ratios EXCEPT:
A
Area of the large piston / Area of the small piston (A / a)
B
Force on the large piston / Force on the small piston (F / f)
C
Work done by the large piston / Work done on the small piston > 1
D
Distance moved by the small piston / Distance moved by the large piston (y1 / y2)
Question 60 of 227
Official Ministerial Exam Question • High-Order Thinking
The relative density (specific gravity) of a substance is defined as:
A
The mass of the substance divided by its volume at 100°C
B
The ratio of the density of the substance to the density of pure water at 4°C
C
The reciprocal of the buoyant force
D
The product of density and the acceleration due to gravity
Question 61 of 227
Official Ministerial Exam Question • High-Order Thinking
In a U-tube manometer containing two immiscible liquids in equilibrium, the heights of the liquid columns measured above the separating surface are:
A
Directly proportional to their densities
B
Equal regardless of the liquids used
C
Proportional to the square of the cross-sectional area of the tube
D
Inversely proportional to their respective densities (h1 / h2 = rho2 / rho1)
Question 62 of 227
Official Ministerial Exam Question • High-Order Thinking
Why are hydroelectric storage dams constructed with a base that is significantly thicker than the crest?
A
To prevent solar radiation from penetrating the foundation
B
To allow fish to swim upstream through drainage gates
C
Because hydrostatic water pressure increases linearly with depth (P = rho * g * h), exerting immense overturning forces at the bottom
D
To reduce the gravitational pull of the bedrock
Question 63 of 227
Official Ministerial Exam Question • High-Order Thinking
A metallic cube of side length 10 cm and density 7800 kg/m^3 is completely submerged in water (density 1000 kg/m^3). The buoyant force (upthrust) acting on the cube is (g = 10 m/s^2):
A
68 N
B
100 N
C
78 N
D
10 N
Question 64 of 227
Official Ministerial Exam Question • High-Order Thinking
Pure water reaches its maximum density (1.000 g/cm^3 or 1000 kg/m^3) at a temperature of:
A
4.0 °C
B
0.0 °C
C
-4.0 °C
D
25.0 °C
Question 65 of 227
Official Ministerial Exam Question • High-Order Thinking
In a hydraulic press, if the radius of the large piston is 4 times that of the small piston, the mechanical advantage is:
A
4
B
16
C
2
D
8
Question 66 of 227
Official Ministerial Exam Question • High-Order Thinking
A mercury manometer connected to a gas tank shows the mercury level in the free arm is 4 cm higher than the gas arm (Pa = 76 cm Hg). The gas pressure is:
A
4 cm Hg
B
72 cm Hg
C
80 cm Hg
D
76 cm Hg
Question 67 of 227
Official Ministerial Exam Question • High-Order Thinking
A U-tube contains water (ρ = 1000 kg/m³) and oil (ρ = 800 kg/m³). If the oil column height above the interface is 10 cm, the balancing water column height is:
A
10 cm
B
6.4 cm
C
12.5 cm
D
8 cm
Question 68 of 227
Official Ministerial Exam Question • High-Order Thinking
Boyle's Law states that for a fixed mass of an ideal gas kept at constant temperature, the volume V is:
A
Directly proportional to pressure
B
Independent of pressure changes
C
Inversely proportional to its absolute pressure P (P1 * V1 = P2 * V2)
D
Directly proportional to absolute temperature
Question 69 of 227
Official Ministerial Exam Question • High-Order Thinking
Charles's Law establishes that at constant pressure, the volume of a given mass of gas is directly proportional to its:
A
Celsius temperature only
B
Square of the absolute temperature
C
Atmospheric density
D
Absolute temperature in Kelvin (T_K = t_C + 273.15)
Question 70 of 227
Official Ministerial Exam Question • High-Order Thinking
The volume expansion coefficient at constant pressure (alpha_v) and the pressure expansion coefficient at constant volume (beta_p) for all ideal gases have the universal constant value of:
A
1 / 273.15 K^-1 (approx. 0.00366 K^-1)
B
8.314 J/(mol.K)
C
1.013 x 10^5 Pa
D
273.15 K
Question 71 of 227
Official Ministerial Exam Question • High-Order Thinking
Absolute zero temperature (0 Kelvin or -273.15 °C) is defined physically as the theoretical temperature at which:
A
The volume and pressure of an ideal gas theoretically extrapolate to zero and translational molecular motion reaches its quantum minimum
B
All liquids solidify into glass
C
Water reaches its maximum density
D
Atmospheric air completely combusts
Question 72 of 227
Official Ministerial Exam Question • High-Order Thinking
The Ideal Gas Law combining all empirical gas relationships is mathematically formulated as:
A
P / V = n * R * T
B
P * T = n * R * V
C
P * V = n * R * T
D
P * V = m * g * h
Question 73 of 227
Official Ministerial Exam Question • High-Order Thinking
A gas cylinder contains 10 liters of gas at a pressure of 3.0 atm. If the volume is reduced to 2.5 liters at constant temperature, the new pressure inside the cylinder will be:
A
12.0 atm
B
6.0 atm
C
1.2 atm
D
7.5 atm
Question 74 of 227
Official Ministerial Exam Question • High-Order Thinking
When a gas trapped inside a rigid container of fixed volume is heated from 27 °C (300 K) to 127 °C (400 K), its pressure increases by a factor of:
A
127 / 27
B
16 / 9
C
2 times
D
4 / 3 (since P1 / T1 = P2 / T2)
Question 75 of 227
Official Ministerial Exam Question • High-Order Thinking
The universal gas constant R in SI units has the numerical value and dimensions of:
A
1.38 x 10^-23 Pa . m^3
B
8.314 J / (mol . K)
C
0.0821 J / mol
D
6.022 x 10^23 J / K
Question 76 of 227
Official Ministerial Exam Question • High-Order Thinking
An air bubble released from the bottom of a deep lake expands in volume as it rises towards the surface because:
A
The hydrostatic pressure decreases as depth decreases, allowing the trapped air to expand according to Boyle's law
B
The bubble absorbs water molecules into its gas phase
C
The water temperature at the surface is near absolute zero
D
Atmospheric pressure increases at the surface
Question 77 of 227
Official Ministerial Exam Question • High-Order Thinking
Real gases behave most closely to an ideal gas under conditions of:
A
Very low pressure and high temperature (where intermolecular attraction forces and molecular volumes become negligible)
B
Zero gravitational acceleration
C
High pressure and near liquefaction point
D
Extremely high pressure and low temperature
Question 78 of 227
Official Ministerial Exam Question • High-Order Thinking
A fixed quantity of an ideal gas has a volume of 600 cm^3 at 27 °C. If the gas is heated to 127 °C under constant pressure, its new volume will be:
A
700 cm^3
B
1200 cm^3
C
800 cm^3
D
900 cm^3
Question 79 of 227
Official Ministerial Exam Question • High-Order Thinking
The pressure of a gas trapped inside an incandescent light bulb is 0.8 atm at room temperature (27 °C). When the bulb operates, the filament heats the gas to 327 °C at constant volume. The operational pressure is:
A
1.6 atm
B
1.2 atm
C
0.96 atm
D
2.4 atm
Question 80 of 227
Official Ministerial Exam Question • High-Order Thinking
If both the absolute temperature and the absolute pressure of a confined ideal gas are doubled, the volume of the gas:
A
Doubles to twice its original volume
B
Quadruples
C
Decreases to one-fourth
D
Remains constant and unchanged
Question 81 of 227
Official Ministerial Exam Question • High-Order Thinking
The density of an ideal gas at temperature T and pressure P is rho. If the pressure is tripled and the absolute temperature is halved, the new density becomes:
A
1.5 rho
B
6 rho (since rho is proportional to P / T)
C
0.67 rho
D
3 rho
Question 82 of 227
Official Ministerial Exam Question • High-Order Thinking
The volume expansion coefficient at constant pressure (alpha_v) of an ideal gas is physically measured using:
A
A torsion balance
B
A hydrometer
C
A venturi meter and manometer
D
Joly's bulb apparatus or Charles's apparatus with a dry mercury droplet index
Question 83 of 227
Official Ministerial Exam Question • High-Order Thinking
An ionic bond is formed primarily between:
A
Noble gas atoms at very low temperatures
B
A metal atom that loses electrons forming a cation and a non-metal atom that gains electrons forming an anion due to electrostatic attraction
C
Two non-metal atoms sharing pairs of valence electrons equally
D
Positive metal ions immersed in a sea of delocalized electrons
Question 84 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following compounds exhibits polar covalent bonding due to a significant difference in electronegativity between 0.4 and 1.7?
A
Water (H2O)
B
Methane (CH4)
C
Chlorine gas (Cl2)
D
Sodium chloride (NaCl)
Question 85 of 227
Official Ministerial Exam Question • High-Order Thinking
The nitrogen molecule (N2) contains a:
A
Double covalent bond
B
Single ionic bond
C
Triple covalent bond (one sigma bond and two pi bonds) sharing 3 electron pairs
D
Coordinate dative bond
Question 86 of 227
Official Ministerial Exam Question • High-Order Thinking
Solid ionic compounds such as crystal NaCl do NOT conduct electricity in the solid state because:
A
Electrons are moving too rapidly
B
They decompose in the presence of air
C
They contain no electrical charges
D
Their ions are tightly locked in fixed positions within the rigid crystal lattice and cannot move freely
Question 87 of 227
Official Ministerial Exam Question • High-Order Thinking
A metallic bond is physically described as the electrostatic attraction between:
A
Dipole molecules in a polar liquid
B
Positive metal cations in the crystal lattice and the mobile sea of delocalized valence electrons
C
Protons and neutrons in the nucleus
D
Positive ions and negative non-metal anions
Question 88 of 227
Official Ministerial Exam Question • High-Order Thinking
Acids are chemical compounds that dissociate in aqueous solutions to produce:
A
Sodium ions and chlorine gas
B
Precipitated metallic salts
C
Hydroxide ions (OH-) turning red litmus paper blue
D
Hydrogen ions (H+ or hydronium ions H3O+), turning blue litmus paper red
Question 89 of 227
Official Ministerial Exam Question • High-Order Thinking
The chemical formula of aluminum sulfate is correctly written as:
A
Al(SO4)3
B
Al2(SO4)3
C
AlSO4
D
Al3(SO4)2
Question 90 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following oxides is classified as an amphoteric oxide that reacts with both acids and bases to yield salt and water?
A
Aluminum oxide (Al2O3)
B
Sodium oxide (Na2O)
C
Carbon dioxide (CO2)
D
Sulfur trioxide (SO3)
Question 91 of 227
Official Ministerial Exam Question • High-Order Thinking
The reaction between an acid and a base to produce a salt and water is known as a:
A
Neutralization reaction
B
Polymerization reaction
C
Thermal decomposition reaction
D
Combustion reaction
Question 92 of 227
Official Ministerial Exam Question • High-Order Thinking
A solution with a pH value of 3.0 is classified as:
A
Weakly basic
B
Neutral
C
Strongly acidic
D
Strongly alkaline
Question 93 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following solutions has the lowest pH value (strongest acidity) at equal concentration?
A
CH3COOH
B
NH4OH
C
NaCl
D
HCl
Question 94 of 227
Official Ministerial Exam Question • High-Order Thinking
Phenolphthalein indicator cannot distinguish between an acidic solution and a neutral solution because:
A
It is colorless in both
B
It precipitates in both
C
It is red in both
D
It is blue in both
Question 95 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following oxides is amphoteric?
A
SO3
B
Na2O
C
ZnO
D
MgO
Question 96 of 227
Official Ministerial Exam Question • High-Order Thinking
According to the 2026/2027 Egyptian STEM biology syllabus, what is the exact scientific deduction regarding: Chargaff's Rules of DNA Base Pairing?
A
Adenine bonds with Guanine via three hydrogen bonds
B
The percentage of %A + %T always equals 50% in all organisms
C
Uracil replaces Thymine in the double helix of nuclear DNA
D
In any double-stranded DNA molecule, the percentage of Adenine equals Thymine (%A = %T) and Guanine equals Cytosine (%G = %C), with purines equaling pyrimidines
Question 97 of 227
Official Ministerial Exam Question • High-Order Thinking
The ion directly responsible for the explosion of synaptic vesicles and the release of acetylcholine in the neuromuscular synapse cleft is:
A
Potassium ion K⁺
B
Sodium ion Na⁺
C
Calcium ion Ca²⁺
D
Chloride ion Cl⁻
Question 98 of 227
Official Ministerial Exam Question • High-Order Thinking
The movement of tension in the tendrils of climbing plants such as peas and grapes depends physiologically on:
A
Water loss through rapid transpiration
B
Degeneration of tendril cells
C
Secretion of gluey substances
D
Slow growth of the area in contact with the support and rapid growth of the area far from it as a result of the varying distribution of auxins
Question 99 of 227
Official Ministerial Exam Question • High-Order Thinking
Rotational cytoplasmic movement inside living plant cells (such as Elodea plants) is indicated by:
A
Stomata open
B
Movement of chloroplasts immersed in the cytoplasm stream in a constant rotational direction
C
Change in cell wall thickness
D
Mitochondrial division
Question 100 of 227
Official Ministerial Exam Question • High-Order Thinking
The movement of hydrotropism in plant roots is considered tropism:
A
Positive (the root bends in the direction of moisture and water concentration)
B
Negatively
C
Unaffected
D
randomly
Question 101 of 227
Official Ministerial Exam Question • High-Order Thinking
The pulling movement occurs in bulbs and corms (such as carcasses and daffodils) with the aim of:
A
Pull the stored ground leg down to an appropriate level from the soil surface to secure and support it against the wind
B
Getting rid of carbon dioxide
C
Light absorption for photosynthesis
D
Repel terrestrial insects
Question 102 of 227
Official Ministerial Exam Question • High-Order Thinking
The hormone that affects both glandular and non-glandular tissue in the adult female body is:
A
Calcitonin hormone
B
Oxytocin
C
Growth hormone
D
Aldosterone hormone
Question 103 of 227
Official Ministerial Exam Question • High-Order Thinking
The hormone responsible for maintaining the balance of minerals in the blood by stimulating the reabsorption of sodium ions and eliminating excess potassium through the kidneys is:
A
Cortisol hormone
B
Thyroxine hormone
C
Insulin hormone
D
Aldosterone
Question 104 of 227
Official Ministerial Exam Question • High-Order Thinking
The direct cause of myxedema in an adult is:
A
Severe deficiency in thyroxine secretion in adulthood
B
Insulin deficiency
C
Hyperactivity of the parathyroid gland
D
Excessive increase in growth hormone
Question 105 of 227
Official Ministerial Exam Question • High-Order Thinking
The gland that secretes both external ductal secretion and non-ductal hormonal secretion directly into the blood is:
A
Thyroid gland
B
pituitary gland
C
Pancreas (common/mixed gland)
D
Adrenal gland
Question 106 of 227
Official Ministerial Exam Question • High-Order Thinking
A hormone secreted from the anterior lobe of the pituitary gland that stimulates the growth of Graafian follicles in the female ovary and the production of sperm in the male testicle is:
A
follicle stimulating hormone (FSH)
B
ACTH hormone
C
Prolactin hormone
D
Luteinizing hormone (LH)
Question 107 of 227
Official Ministerial Exam Question • High-Order Thinking
Antidiuretic hormone (ADH/vasopressin) works to raise blood pressure by:
A
Expansion of the arteries
B
Stimulate sweat
C
Sodium excretion in urine
D
Smooth blood vessel constriction and water reabsorption in nephrons
Question 108 of 227
Official Ministerial Exam Question • High-Order Thinking
The pituitary gland is considered the master of the endocrine glands (the maestro) because:
A
The largest gland by weight
B
It secretes stimulating hormones that control the secretions of most other endocrine glands in the body, such as the thyroid, adrenals, and gonads
C
Connected to the liver
D
Secretes digestive enzymes
Question 109 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following hormones is considered a steroid hormone (derived from fat and cholesterol)?
A
Growth hormone (GH)
B
Thyroxine
C
Progesterone and testosterone
D
Insulin
Question 110 of 227
Official Ministerial Exam Question • High-Order Thinking
The adrenal medulla is stimulated to secrete the emergency hormones adrenaline and noradrenaline via:
A
Rapid and direct sympathetic nervous stimulation in cases of fear, fight, and flight
B
Body temperature change
C
High blood sugar
D
ACTH hormonal stimulation
Question 111 of 227
Official Ministerial Exam Question • High-Order Thinking
When severe dehydration and decreased blood volume and body fluids occur, which of the following hormonal changes occur?
A
Thyroxine secretion stops
B
ADH decreases and insulin increases
C
The secretion of ADH and aldosterone increases to restore water and salts
D
Calcitonin secretion increases
Question 112 of 227
Official Ministerial Exam Question • High-Order Thinking
The hormone that is secreted from the stomach lining and travels through the blood to return to the same stomach, stimulating it to secrete its digestive gastric juices, is:
A
Secretin hormone
B
Pepsin hormone
C
Gastrin hormone
D
Cholecystokinin hormone
Question 113 of 227
Official Ministerial Exam Question • High-Order Thinking
The two hormones that are secreted from the mucous membrane of the small intestine to stimulate the pancreas to secrete its digestive juices are:
A
Insulin and glucagon
B
Thyroxine and calcitonin
C
Prolactin and oxytocin
D
Secretin and cholecystokinin (Secretin & CCK)
Question 114 of 227
Official Ministerial Exam Question • High-Order Thinking
When examining a patient who suffers from severe weight loss, bulging eyes, rapid heart rate, and high temperature, the doctor diagnoses the condition as:
A
Myxedema
B
Exophthalmos caused by excessive secretion of the hormone thyroxine
C
Diabetic urine
D
Dwarfism
Question 115 of 227
Official Ministerial Exam Question • High-Order Thinking
Beta cells in the islets of Langerhans in the pancreas are responsible for secreting the hormone:
A
Insulin
B
Glucagon
C
Somatostatin
D
Pepsin
Question 116 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following conditions leads to increased secretion of parathormone from the parathyroid glands?
A
High blood calcium level
B
Low phosphate
C
Excessive vitamin D excess
D
Low level of ionized calcium in blood plasma
Question 117 of 227
Official Ministerial Exam Question • High-Order Thinking
Auxins in plants (such as indole acetic acid (IAA)) are chemicals secreted from:
A
Dead wood cells
B
Cork cells
C
The growing tops and live plant buds are active and move to the response areas
D
Pollen granules only
Question 118 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following hormones is secreted by the pituitary gland and indirectly affects basic metabolic processes and the speed of oxygen consumption?
A
Insulin hormone
B
Thyroid stimulating hormone (TSH).
C
The hormone oxytocin
D
ADH hormone
Question 119 of 227
Official Ministerial Exam Question • High-Order Thinking
The cells that secrete the hormones oxytocin and ADH and store them in the posterior lobe of the pituitary gland are:
A
Apocrine neurons in the hypothalamus (hypothalamus)
B
Glial cells
C
Frontal lobe glandular cells
D
Pineal gland cells
Question 120 of 227
Official Ministerial Exam Question • High-Order Thinking
The salivary glands and sweat glands in the human body are examples of:
A
Exocrine ductal glands discharge their secretions through special channels outside the bloodstream
B
Common glands
C
Steroid tissue
D
Aductal endocrine glands
Question 121 of 227
Official Ministerial Exam Question • High-Order Thinking
What is the direct physiological effect of injecting a healthy person with an excessive dose of the hormone insulin?
A
A sharp increase in blood sugar
B
A severe drop in blood glucose levels (hypoglycemia) and hypoglycemic coma
C
Increased urine secretion
D
Uric acid accumulation
Question 122 of 227
Official Ministerial Exam Question • High-Order Thinking
Plant hormones are responsible for the phenomenon of leaf fall and fruit ripening and falling. Where the role of a hormonal gas increases:
A
Gibberellic acid
B
Abscisic acid
C
Ethylene gas
D
Auxin IAA
Question 123 of 227
Official Ministerial Exam Question • High-Order Thinking
The lymphocytes responsible for secreting specific antibodies in humoral immunity are:
A
Plasma B cells
B
Macrophages
C
Natural killer (NK) cells
D
Helper T cells (TH)
Question 124 of 227
Official Ministerial Exam Question • High-Order Thinking
Immunoglobulin (antibody), which exists as a pentamer and contains 10 sites to bind to the antigen is:
A
IgM
B
IgA
C
IgG
D
IgE
Question 125 of 227
Official Ministerial Exam Question • High-Order Thinking
Immune chemicals secreted by virus-infected cells to warn neighboring healthy cells to produce enzymes that inhibit virus replication.S is:
A
Chemokines
B
Complements
C
Interleukins
D
Interferons
Question 126 of 227
Official Ministerial Exam Question • High-Order Thinking
Cells that carry CD8 receptors and directly eliminate cancer cells, virus-infected cells, and transplanted organs are:
A
Helper T cells (Th)
B
Memory B cells
C
Mast cells
D
Cytotoxic T cells
Question 127 of 227
Official Ministerial Exam Question • High-Order Thinking
Peyer's spots's Patches) Tiny lymph nodes spread in the mucous membrane lining the:
A
Pharynx
B
Lower part of the small intestine (ileum)
C
Stomach
D
esophagus
Question 128 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following amino acids is considered a non-protein acid produced by plants as protective and toxic substances for microorganisms?
A
Canavanine and cephalosporin
B
Valine and leucine
C
Methionine and tryptophan
D
Glycine and alanine
Question 129 of 227
Official Ministerial Exam Question • High-Order Thinking
The chemical compound secreted by mast cells and basal white blood cells that is responsible for the widening of blood vessels and symptoms of inflammation is:
A
Heparin
B
Interleukin
C
Histamine
D
Albumin
Question 130 of 227
Official Ministerial Exam Question • High-Order Thinking
The protein secreted by cytotoxic T cells (Tc) that creates holes in the plasma membrane of the target cell is:
A
Perforin protein
B
Complement C3
C
Interleukin
D
globulin
Question 131 of 227
Official Ministerial Exam Question • High-Order Thinking
The cells that suppress and inhibit the immune response after eliminating the microbe and secrete lymphokine proteins are:
A
Suppressor T cells
B
Neutrophil cells
C
Plasma cells
D
Helper T cells (Th)
Question 132 of 227
Official Ministerial Exam Question • High-Order Thinking
In the secondary immune response upon exposure to the microbe for the second time, the response is characterized as:
A
Rely only on the first line of defense
B
Slow and takes days
C
It is very rapid and produces huge amounts of antibodies thanks to memory cells, and the individual does not show symptoms of the disease
D
Limited to non-specialized immunity
Question 133 of 227
Official Ministerial Exam Question • High-Order Thinking
The covalent chemical bond that connects the heavy and light peptide chains in an antibody molecule is:
A
Additional peptide bonds
B
Ionic bonds
C
Disulfide Bonds - S-S
D
Weak hydrogen bonds
Question 134 of 227
Official Ministerial Exam Question • High-Order Thinking
The lymphatic organ, which is called the graveyard of old and worn-out red blood cells and contains large numbers of macrophages, is:
A
Thymus gland
B
Tonsils
C
appendix
D
Spleen
Question 135 of 227
Official Ministerial Exam Question • High-Order Thinking
The major histocompatibility complex (MHC) protein associates within the macrophage cell with:
A
Perforin protein
B
Microbe antigen after being broken down by lysosomal enzymes to be displayed on the external surface
C
Secreted antibodies
D
Histamine molecules
Question 136 of 227
Official Ministerial Exam Question • High-Order Thinking
Substances secreted by T helper cells (Th) and acting as a communication tool to activate neighboring B and T cells are:
A
Antibodies
B
Hemoglobin
C
Myoglobin
D
Interleukins
Question 137 of 227
Official Ministerial Exam Question • High-Order Thinking
The antibody that is transferred across the placenta from the blood of the pregnant mother to the blood of the fetus to give it natural, passive, acquired immunity is:
A
IgM
B
IgG
C
IgD
D
IgE
Question 138 of 227
Official Ministerial Exam Question • High-Order Thinking
The method of action of antibodies that is considered the most appropriate and most efficient in inactivating viruses and preventing their penetration into cells is:
A
Deposition method
B
Decomposition method
C
Neutralization method
D
Alignment method
Question 139 of 227
Official Ministerial Exam Question • High-Order Thinking
Complements are a group of plasma proteins that activate when an antibody binds to an antigen and work to:
A
Decomposing the antigenic envelope and dissolving its contents to facilitate their ingestion by macrophages
B
Histamine secretion
C
Activate viruses
D
Blood clotting
Question 140 of 227
Official Ministerial Exam Question • High-Order Thinking
Plant hypersensitivity is an effective immunological method that includes:
A
Secreting nectar to attract bees
B
Stomata open at night
C
Root loss
D
The plant kills some of its infected tissues and cells locally to prevent the spread of the microbe to healthy tissues
Question 141 of 227
Official Ministerial Exam Question • High-Order Thinking
Natural killer (NK) cells attack and kill cancer cells and virus-infected cells by:
A
Secretion of antibodies
B
Secretion of specialized digestive enzymes without the need for prior specific antigen recognition
C
Swallow the cells whole
D
Histamine secretion
Question 142 of 227
Official Ministerial Exam Question • High-Order Thinking
The surface immune receptor characteristic of T helper cells (Th) that enables them to recognize the antigen complex with the MHC protein is:
A
CD8 receptor
B
CD3 receptor
C
BCR receptor
D
CD4 receptor
Question 143 of 227
Official Ministerial Exam Question • High-Order Thinking
Vaccination gives humans immunity:
A
Acquired long-term positivity for the formation of memory cells
B
Temporary negativity that disappears within weeks
C
Innate, inherited
D
Not specialized
Question 144 of 227
Official Ministerial Exam Question • High-Order Thinking
Injection with serum (Antiserum) containing ready-made antibodies to neutralize scorpion venom gives the patient immunity:
A
A rapid and temporary acquired negativity that is not accompanied by memory cells
B
Innate
C
Cellular induced
D
Lasting positivity
Question 145 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following immune structures represents the first line of defense in the human body to prevent the entry of pathogens?
A
Intact skin with its stratum corneum, mucus, HCl in the stomach, and saliva saturated with lysozyme
B
Toxic T cells
C
Antibodies
D
Macrophages
Question 146 of 227
Official Ministerial Exam Question • High-Order Thinking
The enzymes secreted by the plant to break down bacterial toxins and convert them into non-toxic compounds are:
A
Detoxifying enzymes
B
pepsin enzymes
C
RNA polymerase enzymes
D
Palace enzymes
Question 147 of 227
Official Ministerial Exam Question • High-Order Thinking
Monocytes are functionally capable of leaving the bloodstream when needed:
A
Transformation into B cells
B
Transform into active macrophages to engulf microbes and cellular debris
C
Antibody formation
D
Histamine secretion
Question 148 of 227
Official Ministerial Exam Question • High-Order Thinking
Lymphotoxins secreted by cytotoxic T cells (Tc) eliminate the infected cell by:
A
Immunosuppression
B
Calcium withdrawal
C
Blood plasma coagulation
D
Activation of certain genes within the nucleus of the infected cell, which leads to the fragmentation of its genetic material and its programmed death (Apoptosis).
Question 149 of 227
Official Ministerial Exam Question • High-Order Thinking
The substance that the plant secretes to close wounds in its woody stems and completely isolate the affected tissue from the air and microbes is:
A
Gum and cork
B
Ascorbic acid
C
Monosaccharides
D
Liquid auxins
Question 150 of 227
Official Ministerial Exam Question • High-Order Thinking
The phenomenon of natural parthenogenesis in honey bees results in:
A
Fertile queens (2N)
B
Female workers only
C
Bees are always male, and their somatic cells are haploid (1N) resulting from an unfertilized egg that grows mitotically.
D
Diploid males
Question 151 of 227
Official Ministerial Exam Question • High-Order Thinking
Reproduction by peaceful association in two adjacent threads of the spirogyra moss (Rem al-Barak) occurs in the case of:
A
Mild spring
B
Complete darkness
C
The environment is exposed to drought, change in water purity, or change in temperature (unsuitable conditions)
D
Abundance of pure fresh water
Question 152 of 227
Official Ministerial Exam Question • High-Order Thinking
In the life cycle of the fougere plant (a fern), the haploid (N) gametophyte produces its male and female gametes by:
A
Mitosis within antheridia and archegonia
B
Direct meiosis
C
Surface budding
D
Regeneration
Question 153 of 227
Official Ministerial Exam Question • High-Order Thinking
The apple is considered a false fruit from a morphological and anatomical perspective because:
A
It is made without seeds
B
The cup leaves become greasy
C
The edible, fatty part that is lubricated by food is the takht, not the ovary of the flower
D
Produced from a hermaphrodite flower
Question 154 of 227
Official Ministerial Exam Question • High-Order Thinking
Double fertilization in flowering plants involves two fusions:
A
The fusion of two pollen grains with one egg
B
Fusion of petals with sepals
C
Chromosome duplication in Takht cells
D
The fusion of the zygote nucleus (N) with the egg nucleus (N) to form the zygote (2N), and the fusion of the second nuclei (N) with the two polar nuclei (2N) to form the sperm nucleus.Dosperm (3N)
Question 155 of 227
Official Ministerial Exam Question • High-Order Thinking
The hormone that is secreted from the corpus luteum and reaches its maximum concentration on days 21 to 23 of menstruation is:
A
Estrogen
B
LH hormone
C
Progesterone
D
FSH hormone
Question 156 of 227
Official Ministerial Exam Question • High-Order Thinking
The location where fertilization of the egg by the sperm occurs in the human female reproductive system is:
A
Internal uterine cavity
B
the vagina
C
Directly to the ovary
D
First third of the fallopian tube (near the infundibulum)
Question 157 of 227
Official Ministerial Exam Question • High-Order Thinking
The Cowper glands and the prostate gland in the male reproductive system secrete an alkaline fluid that passes into the urethra to:
A
Secretion of testosterone
B
Sperm production
C
Balancing the acidity of the urethra to ensure the passage and safety of sperm
D
Semen storage
Question 158 of 227
Official Ministerial Exam Question • High-Order Thinking
The enzyme found in the apical body (Acrosome) of the sperm that helps it penetrate the compact envelope of the egg is:
A
Hyaluronidase enzyme
B
Amylase enzyme
C
Cholinesterase enzyme
D
pepsin enzyme
Question 159 of 227
Official Ministerial Exam Question • High-Order Thinking
Identical (monozygotic) twins arise genetically as a result of:
A
Fertilization of two eggs by two different sperm
B
Artificial parthenogenesis
C
Fertilization of one egg by one sperm, then the resulting cell mass is divided into two parts that are identical in genetic makeup and sex.
D
Fertilization of one egg by two sperm
Question 160 of 227
Official Ministerial Exam Question • High-Order Thinking
The umbilical cord in the human fetus contains blood vessels that are characterized by:
A
One artery and two veins
B
Devoid of blood vessels
C
All its vessels carry oxygenated blood
D
Two arteries transport deoxygenated blood and waste from the fetus to the placenta, and one vein transports oxygenated blood and nutrients from the placenta to the fetus.
Question 161 of 227
Official Ministerial Exam Question • High-Order Thinking
The contraceptive method that prevents the fertilized egg from settling in the uterine lining without hindering the ovulation or fertilization processes is:
A
Surgical ligation of the fallopian tubes
B
IUD
C
Contraceptive pills
D
Condom
Question 162 of 227
Official Ministerial Exam Question • High-Order Thinking
Sertoli cells in the seminiferous tubules of the human male testicle play a functional role in:
A
Secretion of testosterone
B
Meiosis to produce precursors
C
Excretion of fructose
D
The secretion of a fluid that nourishes sperm inside the testicle and is thought to have an immunological function
Question 163 of 227
Official Ministerial Exam Question • High-Order Thinking
Fructose, which is found in semen to nourish sperm outside the testicle, is secreted by:
A
Tomorrow Cooper
B
Epididymis
C
The seminal vesicles
D
Prostate gland
Question 164 of 227
Official Ministerial Exam Question • High-Order Thinking
In the life cycle of the Plasmodium malaria parasite, the human infective phase is:
A
Sporozoites
B
Merozoites
C
Gametophytes
D
Kinetic phase (okinete)
Question 165 of 227
Official Ministerial Exam Question • High-Order Thinking
The infective stage of the female Anopheles mosquito in the life cycle of Plasmodium malaria is:
A
Merozoites
B
Zygote
C
Gametocytes
D
Sporozoites
Question 166 of 227
Official Ministerial Exam Question • High-Order Thinking
Cultivation of plant tissues in a semi-natural nutrient medium (such as coconut milk) is scientific proof of:
A
Effect of thyroxine
B
The necessity of double fertilization
C
A complete living plant cell contains all the genetic information necessary to form a new complete plant
D
Seeds are asexual
Question 167 of 227
Official Ministerial Exam Question • High-Order Thinking
In the human female, the second (delayed/conditional) meiotic division of the secondary oocyte takes place in:
A
Graaf's vesicle
B
Uterine cavity
C
Ovaries before ovulation
D
The fallopian tube when the sperm enters the head for fertilization to occur
Question 168 of 227
Official Ministerial Exam Question • High-Order Thinking
The decomposition of the corpus luteum in the ovary of a non-pregnant woman at the end of the menstrual cycle results in:
A
Continued growth of the uterine lining
B
Secretion of huge amounts of LH
C
A sharp drop in the concentration of the hormone progesterone leads to the breakdown of the uterine lining, the rupture of its capillaries, and the occurrence of menstruation
D
Placenta formation
Question 169 of 227
Official Ministerial Exam Question • High-Order Thinking
The fetal membrane that directly surrounds the fetus and secretes a fluid that protects it from shock and dehydration and facilitates its movement is:
A
Amnion
B
Amniotic membrane (Chorion)
C
Plasma membrane
D
Vitelline membrane
Question 170 of 227
Official Ministerial Exam Question • High-Order Thinking
The outer embryonic membrane that surrounds the uterine membrane and from which digital villi emerge, which are immersed in the uterine lining to form the placenta, is:
A
Amniotic membrane (Chorion)
B
Corpus luteum
C
umbilical cord
D
Sagging membrane
Question 171 of 227
Official Ministerial Exam Question • High-Order Thinking
Asexual reproduction differs from sexual reproduction in that:
A
It is based on a single parental individual and maintains genetic stability over generations because it is based on mitosis
B
Provides great genetic diversity
C
It always requires the formation of gametes
D
Expensive in energy and time
Question 172 of 227
Official Ministerial Exam Question • High-Order Thinking
Artificial parthenogenesis in flowering plants (such as the production of seedless oranges or watermelons) is carried out by:
A
Spraying flower stigmas with pollen extract or indole acetic acid to stimulate the ovary to form fruit without fertilization
B
Tissue culture
C
Pen vaccination
D
Irradiating seeds with X-rays
Question 173 of 227
Official Ministerial Exam Question • High-Order Thinking
Hydra and planaria share the ability to reproduce asexually by:
A
Budding only
B
Bacteria formation
C
Longitudinal binary fission
D
Regeneration
Question 174 of 227
Official Ministerial Exam Question • High-Order Thinking
Interstitial cells in the human male testicle respond directly and secrete testosterone under the influence of a pituitary hormone:
A
FSH hormone
B
Luteinizing hormone (LH)
C
Growth hormone
D
Prolactin hormone
Question 175 of 227
Official Ministerial Exam Question • High-Order Thinking
Combined contraceptive pills are considered an effective method because they:
A
The fallopian tubes close mechanically
B
Placental abruption
C
It kills sperm
D
It contains synthetic hormones similar to estrogen and progesterone that inhibit the secretion of FSH and LH from the pituitary, thus preventing the maturation of eggs and the occurrence of ovulation.
Question 176 of 227
Official Ministerial Exam Question • High-Order Thinking
The maximum number of pollen grains that can be produced from the anther of a flower containing 4 sacs, each sac with 20 germinal cells (2N) is:
A
640 grain
B
320 Pollen pill
C
160 grain
D
80 grain
Question 177 of 227
Official Ministerial Exam Question • High-Order Thinking
The motile phase (motile zygote / ookinete) in the life cycle of Plasmodium malaria is characterized by:
A
It is diploid (2N) and penetrates the mosquito's stomach wall and turns into an egg sac
B
It attacks red blood cells
C
It secretes malaria toxin
D
Haploid group N
Question 178 of 227
Official Ministerial Exam Question • High-Order Thinking
The number of polar bodies resulting from the maturation and fertilization of 3 primary oocytes in the ovary of a human female is equal to:
A
6 Polar bodies
B
3 Polar bodies
C
9 Polar bodies (assuming division of the first polar body)
D
12 A polar body
Question 179 of 227
Official Ministerial Exam Question • High-Order Thinking
The decisive experiment for Hershey and Chase (Hershey & Chase) To prove that DNA is the genetic material of bacteriophages, I relied on:
A
Use of deoxyribonuclease enzyme to analyze protein
B
Isolation of bacterial plasmids
C
Radioactive nitrogen and carbon numbering
D
Radioactive phosphorus numbering P-32 in DNA and radioactive sulfur numbering S-35 in the protein envelope
Question 180 of 227
Official Ministerial Exam Question • High-Order Thinking
The enzyme used in the crucial experiment to verify the experiments of Avery and his colleagues, which completely analyzes DNA and does not affect protein or RNA, is:
A
Ribonuclease enzyme
B
DNA polymerase enzyme
C
Deoxyribonuclease enzyme
D
pepsin enzyme
Question 181 of 227
Official Ministerial Exam Question • High-Order Thinking
According to Chargaff's rules's Rules) In the DNA double helix, the equal ratio is always:
A
A = G And T = C
B
A + T = G + C always
C
A / T = 2
D
The ratio of adenine A equals thymine T, and the ratio of guanine G equals cytosine C (A+G). = T+C)
Question 182 of 227
Official Ministerial Exam Question • High-Order Thinking
The enzyme responsible for separating the two strands of DNA from each other by breaking hydrogen bonds during replication is:
A
DNA polymerase
B
Palace enzyme
C
Helicase enzyme
D
Ligase
Question 183 of 227
Official Ministerial Exam Question • High-Order Thinking
DNA polymerase always adds new nucleotides in a specific direction:
A
From party 5' To party 3' For new growing bar only
B
From party 3' to 5' only
C
In both directions together
D
randomly
Question 184 of 227
Official Ministerial Exam Question • High-Order Thinking
Okazaki Fragments formed on the die strip (5' to 3') During DNA replication they are joined by an enzyme:
A
Polymerase enzyme
B
Tac polymerase enzyme
C
DNA ligase
D
Helix enzyme
Question 185 of 227
Official Ministerial Exam Question • High-Order Thinking
Histone proteins responsible for shortening the length of the DNA molecule ten times and forming nucleosomes are characterized by being rich in the two basic amino acids:
A
Glycine and alanine
B
Methionine and tryptophan
C
Arginine and lysine (Arginine & Lysine)
D
Glutamic acid and aspartic acid
Question 186 of 227
Official Ministerial Exam Question • High-Order Thinking
If a sample of a DNA double helix contains 30% Cytosine (C), the percentage of adenine (A) bases in this sample is equal to:
A
20%
B
40%
C
70%
D
30%
Question 187 of 227
Official Ministerial Exam Question • High-Order Thinking
The number of hydrogen bonds between the nitrogenous base pair guanine and cytosine (G - C) is:
A
4 Links
B
3 Hydrogen bonds
C
Two hydrogen bonds
D
One bond
Question 188 of 227
Official Ministerial Exam Question • High-Order Thinking
A synthetic chromosome mutation that occurs when a piece of chromosome separates, wraps around itself at an angle of 180 degrees, and then rejoins in the same position is called:
A
Deletion mutation
B
Transmission mutation
C
Repetition mutation
D
Inversion mutation
Question 189 of 227
Official Ministerial Exam Question • High-Order Thinking
The sequence is repeated more than one hundred thousand times in the middle of one of the chromosomes of the Drosophila insect (fruit fly) and does not code for any protein:
A
AGACT
B
AUG
C
UAA
D
TATAAT
Question 190 of 227
Official Ministerial Exam Question • High-Order Thinking
Telomeres are found at the ends of eukaryotic chromosomes and perform an important function in:
A
Protecting chromosomes from corrosion and merging with each other and maintaining their structure
B
Construction of ribosomes
C
Synthesis of enzymes
D
Centromere doubling
Question 191 of 227
Official Ministerial Exam Question • High-Order Thinking
A segment of a DNA double helix consisting of 600 nucleotides. The number of complete turns in this segment is equal to:
A
15 roll
B
10 Rolls
C
30 Full roll
D
60 roll
Question 192 of 227
Official Ministerial Exam Question • High-Order Thinking
DNA Repair Enzymes, which number approximately 20 enzymes, depend for their work on:
A
The presence of a corresponding healthy template strip complementary to the damaged strip to guide its sequence in repair
B
Production of lipoproteins
C
Heat irradiation of the cell
D
Destruction of the infected cell
Question 193 of 227
Official Ministerial Exam Question • High-Order Thinking
Which of the following organisms has its genetic material as a single molecule of RNA rather than DNA?
A
Escherichia coli bacteria
B
Bacteriophage T2
C
Human immunodeficiency virus (HIV), polio virus, influenza and coronavirus
D
Yeast
Question 194 of 227
Official Ministerial Exam Question • High-Order Thinking
In Griffith's bacterial transformation experiment, mice died when they were injected with:
A
Live R bacteria alone
B
Sterile saline solution
C
Heat-killed S bacteria alone
D
A mixture of heat-killed S bacteria with live R bacteria
Question 195 of 227
Official Ministerial Exam Question • High-Order Thinking
The atom in the pentose sugar molecule (dioxyribose) to which the nitrogenous base is linked by a covalent bond is:
A
Carbon atom number 2'
B
Carbon atom number 5'
C
Carbon atom number 1' (C1')
D
Carbon atom number 3'
Question 196 of 227
Official Ministerial Exam Question • High-Order Thinking
Party 3' For a DNA strand that ends with a group:
A
Free amine (-NH2)
B
Free carboxylate (-COOH)
C
Free phosphate (-PO4)
D
Free hydroxyl (-OH)
Question 197 of 227
Official Ministerial Exam Question • High-Order Thinking
In prokaryotic cells (such as bacteria), a single circular DNA molecule attaches to the plasma membrane at:
A
One or more sites from which DNA replication begins
B
Nuclear envelope
C
Centrosome
D
Ribosome
Question 198 of 227
Official Ministerial Exam Question • High-Order Thinking
Common and economically beneficial chromosome duplication in the plant kingdom (such as strawberries, wheat, and apples) leads to:
A
Plant sterility and death
B
Larger cells and tissues and larger, sweeter and more productive fruits
C
Root loss
D
Loss of chlorophyll
Question 199 of 227
Official Ministerial Exam Question • High-Order Thinking
A chemical substance used in the laboratory to cause mutations and chromosome duplication in the growing tips of plants is:
A
Hyaluronic acid
B
Glycerin
C
Sucrose solution
D
Colchicine, mustard gas, or nitrous acid
Question 200 of 227
Official Ministerial Exam Question • High-Order Thinking
Mutations that are inherited to future generations and occur in reproductive cells that produce gametes are called:
A
Temporary spikes
B
Gamete mutations
C
Somatic mutations
D
Rebound mutations
Question 201 of 227
Official Ministerial Exam Question • High-Order Thinking
The Ancon breed mutation in sheep with short, arched legs is considered a mutation:
A
Harmful innovation
B
Numerical chromosome
C
Fatal to fetuses
D
A useful mechanism that the breeder kept in mind to prevent sheep from jumping fences and damaging crops
Question 202 of 227
Official Ministerial Exam Question • High-Order Thinking
The percentage of DNA encoding the construction of proteins and enzymes in the genetic content of eukaryotic cells (such as humans) represents approximately:
A
50%
B
100%
C
Less than 2% Of the total cell genome
D
More than 90%
Question 203 of 227
Official Ministerial Exam Question • High-Order Thinking
Connecting two complementary DNA strands by hydrogen bonds makes them:
A
Two parallel strands in opposite directions that are chemically complementary
B
Two exactly identical bars in the same direction
C
connected by peptide bonds
D
criss-crossing each lap
Question 204 of 227
Official Ministerial Exam Question • High-Order Thinking
The amount of DNA in a human female secondary oocyte compared to a resting somatic skin cell (before replication begins) is:
A
Equal (contains 46 DNA molecules in the form of 23 diploid chromosomes)
B
Quarter
C
Weakness
D
Half the quantity
Question 205 of 227
Official Ministerial Exam Question • High-Order Thinking
The standard start codon in an mRNA molecule recognized by the first tRNA molecule carrying methionine is:
A
UAG
B
UAA
C
AUG
D
UGA
Question 206 of 227
Official Ministerial Exam Question • High-Order Thinking
Stop codons that bind to the release factor to terminate the translation process are:
A
AUG And GUG and UUG
B
AAA And UUU and GGG
C
CCC And GGG and TTT
D
UAA And UAG and UGA
Question 207 of 227
Official Ministerial Exam Question • High-Order Thinking
The anticodon on the tRNA molecule carrying methionine is:
A
AUG
B
GUA
C
UAC
D
CAU
Question 208 of 227
Official Ministerial Exam Question • High-Order Thinking
The enzyme responsible for constructing an mRNA strand from one of the two DNA strands (template strand 3' to 5') he:
A
Binding enzyme
B
DNA polymerase enzyme
C
RNA polymerase
D
Palace enzyme
Question 209 of 227
Official Ministerial Exam Question • High-Order Thinking
The polyadenyne tail (Poly-A Tail) added to the end of the mRNA molecule in eukaryotes consists of about 200 adenine nucleotides and functionally functions to:
A
Protecting the mRNA molecule from degradation by enzymes in the cytoplasm
B
Formation of the nuclear envelope
C
Binding to the polymerase enzyme
D
Encoding polar amino acids
Question 210 of 227
Official Ministerial Exam Question • High-Order Thinking
The enzyme that catalyzes the peptidyl transferase reaction and the formation of the peptide bond between amino acids during translation is:
A
Part of the rRNA molecule that makes up the subunit of the ribosomal subunit
B
Release factor protein
C
DNA polymerase enzyme
D
Helix enzyme
Question 211 of 227
Official Ministerial Exam Question • High-Order Thinking
Bacterial restriction endonucleases recognize specific nucleotide sequences called recognition sites, and are characterized by:
A
Stop codons only
B
Lipoprotein molecules
C
Palindromes of 4 to 8 pairs read in the same order on both strands in 5′ direction.' to 3'
D
Asymmetric repetitive sequences
Question 212 of 227
Official Ministerial Exam Question • High-Order Thinking
The enzyme extracted from RNA viruses and used to convert mRNA into a single strand of complementary DNA (cDNA) is:
A
RNA polymerase enzyme
B
Ligase enzyme
C
Palace enzyme
D
Reverse transcriptase
Question 213 of 227
Official Ministerial Exam Question • High-Order Thinking
The thermal multiplex device (PCR - Polymerase Chain Reaction) depends on an enzyme that tolerates high temperatures called:
A
Human DNA polymerase enzyme
B
Taq polymerase enzyme
C
RNA polymerase enzyme
D
Amylase enzyme
Question 214 of 227
Official Ministerial Exam Question • High-Order Thinking
DNA hybridization depends on the ability of single strands from different sources to combine if:
A
They are just the same height and weight
B
Treatment with shortening enzyme
C
Made in the same cell
D
They contain complementary sequences of nitrogenous bases and are linked by hydrogen bonds
Question 215 of 227
Official Ministerial Exam Question • High-Order Thinking
The number of codons that code for the 20 amino acids in the genetic table is equal to:
A
64 Codona
B
61 Codons (out of a total of 64 codons after excluding the three stop codons)
C
32 Codona
D
20 Codona
Question 216 of 227
Official Ministerial Exam Question • High-Order Thinking
The genetic code is characterized as universal because:
A
It is found in the nucleus only
B
It does not change with mutations
C
The same codons code for the same amino acids in all organisms from bacteria to humans, confirming the common origin of life
D
It consists of only two letters
Question 217 of 227
Official Ministerial Exam Question • High-Order Thinking
Modifying enzymes produced by bacteria work to:
A
Adding methyl groups (-CH3) to the nucleotides of recognition sites in bacterial DNA to protect it from their shortening enzymes.
B
Cell wall construction
C
Cracking viruses
D
Sugar analysis
Question 218 of 227
Official Ministerial Exam Question • High-Order Thinking
The first human protein produced commercially using recombinant DNA technology to treat diabetics is:
A
Growth hormone
B
Interferon protein
C
Hemoglobin
D
Human hormone insulin (Insulin)
Question 219 of 227
Official Ministerial Exam Question • High-Order Thinking
The number of amino acid molecules in a polypeptide chain resulting from mRNA translation consisting of 303 nucleotides, including the start and stop codons, is equal to:
A
101 Acid
B
99 Acid
C
300 Acid
D
100 Amino acid
Question 220 of 227
Official Ministerial Exam Question • High-Order Thinking
The two main functional sites on the tRNA molecule are:
A
Start location and stop location
B
Phosphate site and sugar site
C
The amino acid binding site is at the 3′ end' (sequence CCA), and anticodon site
D
DNA polymerase site and binding site
Question 221 of 227
Official Ministerial Exam Question • High-Order Thinking
In gene cloning technology, a ligase is used to:
A
Linking the integrated sticky ends of a target gene to the sticky ends of a circular plasmid
B
Breaking down proteins
C
Cut the plasmid
D
mRNA transcription
Question 222 of 227
Official Ministerial Exam Question • High-Order Thinking
Polyribosome is a vital cellular structure consisting of:
A
A large number of ribosomes (up to 100 ribosomes) attach to a single mRNA molecule to translate it simultaneously and quickly build many copies of the protein.
B
Accumulated peripheral granules
C
Fusion of two nuclei
D
Mitochondrial aggregation
Question 223 of 227
Official Ministerial Exam Question • High-Order Thinking
In eukaryotic cells, rRNA molecules are synthesized and assembled under ribosomal subunits within:
A
Nucleolus
B
Golgi apparatus
C
directly into the cytoplasm
D
Smooth endoplasmic reticulum
Question 224 of 227
Official Ministerial Exam Question • High-Order Thinking
Sticky Ends resulting from the action of shortening enzymes are characterized by:
A
Short, extended single strands of unpaired nucleotides capable of spontaneous association with complementary ends
B
Collagen thickened ends
C
Inactive phosphate sequences
D
Ends surrounded by peptide bonds
Question 225 of 227
Official Ministerial Exam Question • High-Order Thinking
Experiments using genes for resistance to insect pests in crop plants (such as the Bacillus thuringiensis gene) are an application to:
A
Parthenogenetic fruiting
B
Genetic engineering and development of genetically modified plants resistant to pests without chemical pesticides
C
Artificial parthenogenesis
D
Propagation by hydroponics
Question 226 of 227
Official Ministerial Exam Question • High-Order Thinking
The two sites on the subunit of the ribosomal subunit where the two tRNA molecules stabilize during polypeptide chain elongation are:
A
The location of the palace and the location of the IUD
B
Coiling site and binding site
C
Location 5' And site 3'
D
Peptidyl site (P) and aminoacyl site (A)
Question 227 of 227
Official Ministerial Exam Question • High-Order Thinking
The global scientific project that was able to decipher and arrange more than 3 billion pairs of nitrogenous bases in human cells is:
A
Virus study project
B
Stem cell project
C
Human Genome Project
D
Acquired immunity project
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Side-by-side comparison of your answers and official ministerial solutions with detailed scientific explanations.
Question 1
Unanswered
The stop codons that signal termination of translation on an mRNA molecule include:
(A)
AUG, UAA, UGA
(B)
UAC, UGG, UAA
(C)
UAA, UAG, UGA
(D)
GUA, CAU, UAG
Official Scientific Justification: UAA, UAG, and UGA are the three universal termination codons recognized by Release Factor.
Question 2
Unanswered
If a double-stranded DNA sample contains 28% Adenine, what is the exact percentage of Cytosine in this sample?
(A)
22%
(B)
28%
(C)
56%
(D)
44%
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Biology curriculum.
Question 3
Unanswered
Which enzyme is responsible for linking Okazaki fragments into a continuous strand during lagging strand replication?
(A)
DNA Polymerase
(B)
Reverse Transcriptase
(C)
DNA Ligase
(D)
DNA Helicase
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Biology curriculum.
Question 4
Unanswered
What is the structural characteristic of a restriction endonuclease recognition site?
(A)
It consists of 15-20 repetitive nucleotides.
(B)
It contains only adenine and thymine bases.
(C)
It is a palindromic sequence reading identical 5' to 3' on both strands.
(D)
It always begins with the start codon AUG.
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Biology curriculum.
Question 5
Unanswered
Why is the genetic code described as 'degenerate' or 'redundant'?
(A)
One codon can code for multiple different amino acids.
(B)
The genetic code differs completely between bacteria and humans.
(C)
The genetic code decays as the cell ages.
(D)
Multiple different codons can code for the same single amino acid.
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Biology curriculum.
Question 6
Unanswered
Which of the following first-row transition metal ions exhibits the highest theoretical magnetic moment in its ground state?
(A)
Cr3+ ([Ar] 3d3 with 3 unpaired electrons)
(B)
Zn2+ ([Ar] 3d10 with 0 unpaired electrons)
(C)
Cu2+ ([Ar] 3d9 with 1 unpaired electron)
(D)
Fe3+ ([Ar] 3d5 with 5 unpaired electrons)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 7
Unanswered
The main chemical reducing agent inside the Midrex furnace and its industrial source are respectively:
(A)
Carbon dioxide mixed with limestone
(B)
Water gas (mixture of CO and H2) produced from natural gas (methane CH4)
(C)
Pure carbon monoxide (CO) produced from metallurgical coke
(D)
Hydrogen gas produced from the electrolysis of water
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 8
Unanswered
A transition element whose +5 oxidation state compound (V2O5) is widely utilized as an industrial catalyst in the Contact Process for sulfuric acid manufacturing and as a colorant in ceramics is:
(A)
Scandium (21Sc)
(B)
Cobalt (27Co)
(C)
Manganese (25Mn)
(D)
Vanadium (23V)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 9
Unanswered
When dry chlorine gas is passed over red-hot iron filings, iron(III) chloride (FeCl3) is exclusively formed rather than iron(II) chloride because:
(A)
Iron(II) chloride spontaneously sublimes into thin air
(B)
The reaction occurs strictly in an alkaline medium
(C)
Chlorine gas is a powerful oxidizing agent that readily oxidizes any formed Fe2+ to Fe3+
(D)
Chlorine cannot react with the inner 3d electrons
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 10
Unanswered
Which of the following alloys is classified as an interstitial alloy?
(A)
Carbon steel (Iron and Carbon where small carbon atoms occupy interstitial voids)
(B)
Stainless steel (Iron, Chromium, and Nickel)
(C)
Duralumin (Aluminum and Copper)
(D)
Brass (Copper and Zinc)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 11
Unanswered
The electronic configurations of both Chromium (24Cr) and Copper (29Cu) are anomalous due to the enhanced stability associated with:
(A)
Half-filled (3d5) and completely filled (3d10) d-subshells respectively
(B)
Pairing of all electrons in the outer valence level
(C)
High electronegativity differences
(D)
Completely empty 4s subshells
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 12
Unanswered
Concentrated nitric acid (HNO3) induces chemical passivity on the surface of iron metal due to:
(A)
The precipitation of elemental sulfur on the surface
(B)
The instantaneous dissolution of iron into gaseous ions
(C)
The formation of an extremely thin, non-porous protective oxide film that halts further reaction
(D)
Complete neutralization of the acid
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 13
Unanswered
The atomic radii of the elements from Chromium to Copper remain remarkably steady and nearly constant across the first transition series because of:
(A)
The mutual compensation between the increasing nuclear charge and the repulsive forces among accumulated 3d electrons
(B)
Decreasing ionization energies
(C)
The identical number of neutrons in their nuclei
(D)
The sudden increase in atomic mass
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 14
Unanswered
Magnetic iron oxide (Magnetite, Fe3O4) is chemically considered a mixed oxide because reacting it with hot concentrated sulfuric acid yields:
(A)
Elemental iron and sulfur dioxide
(B)
A mixture of iron(II) sulfate, iron(III) sulfate, and water vapor
(C)
Iron(II) sulfate and hydrogen gas only
(D)
Iron(III) sulfate only
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 15
Unanswered
An aqueous solution of titanium(IV) chloride (TiCl4) is diamagnetic and colorless because:
(A)
It absorbs all visible wavelengths of light
(B)
Chlorine ions quench all magnetic dipoles
(C)
Titanium is an alkali earth metal
(D)
The Ti4+ ion has an electronic configuration of [Ar] 3d0, devoid of unpaired d-electrons
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 16
Unanswered
When dilute hydrochloric acid is added to a solid salt, a gas is evolved with a pungent odor that turns acidified potassium dichromate paper green while a colloidal yellow precipitate of sulfur separates in the reaction vessel. The anion is:
(A)
Sulfide (S^2-)
(B)
Sulfate (SO4^2-)
(C)
Thiosulfate (S2O3^2-)
(D)
Sulfite (SO3^2-)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 17
Unanswered
To distinguish between a white precipitate of barium sulfate (BaSO4) and a white precipitate of barium phosphate (Ba3(PO4)2), one should add:
(A)
Dilute hydrochloric acid (Ba3(PO4)2 dissolves while BaSO4 remains insoluble)
(B)
Boiling distilled water
(C)
Concentrated nitric acid in the dark
(D)
Ammonium hydroxide solution
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 18
Unanswered
A metal cation that forms a gelatinous white precipitate with NaOH which completely redissolves in excess reagent to form a soluble clear solution is:
(A)
Fe3+
(B)
Ca2+
(C)
Al3+ (due to the formation of soluble sodium meta-aluminate NaAlO2)
(D)
Fe2+
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 19
Unanswered
In a titration experiment, 20.0 mL of 0.15 M H2SO4 is completely neutralized by 30.0 mL of NaOH solution. The molar concentration of the NaOH solution is:
(A)
0.20 M
(B)
0.10 M
(C)
0.30 M
(D)
0.05 M
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 20
Unanswered
The indicator that exhibits a yellow color in acidic medium, blue in alkaline medium, and green in neutral medium is:
(A)
Litmus solution
(B)
Bromothymol blue
(C)
Methyl orange
(D)
Phenolphthalein
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Chemistry curriculum.
Question 21
Unanswered
A person who skillfully makes beautiful objects by hand is called a/an ________.
(A)
pilot
(B)
scientist
(C)
artisan
(D)
engineer
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the English curriculum.
Question 22
Unanswered
While the students ________ in the art workshop, the tour guide arrived.
(A)
worked
(B)
work
(C)
were working
(D)
are working
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the English curriculum.
Question 23
Unanswered
We visited the pottery village in Fustat ________ our holiday in Cairo.
(A)
when
(B)
as
(C)
during
(D)
while
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the English curriculum.
Question 24
Unanswered
Potters use high-temperature ovens called ________ to bake and harden clay vessels.
(A)
looms
(B)
fridges
(C)
kilns
(D)
blenders
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the English curriculum.
Question 25
Unanswered
Electric buses and monorails produce zero exhaust fumes, making them ________ forms of transport.
(A)
polluting
(B)
dangerous
(C)
noisy
(D)
eco-friendly
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the English curriculum.
Question 26
Unanswered
Watch out! The ladder is shaking violently. You ________ fall!
(A)
are going to
(B)
have
(C)
will
(D)
were
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the English curriculum.
Question 27
Unanswered
I have already booked the flight tickets. I ________ to London next Friday.
(A)
will travel
(B)
traveled
(C)
am traveling
(D)
travel
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the English curriculum.
Question 28
Unanswered
The Cairo Monorail travels on an elevated single-beam track to avoid urban traffic ________.
(A)
congestion
(B)
stations
(C)
gardens
(D)
comfort
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the English curriculum.
Question 29
Unanswered
The n-th term of an arithmetic sequence with first term a and common difference d is given by:
(A)
T_n = a + n * d
(B)
T_n = 1/2 n (2a + d)
(C)
T_n = a * r^(n - 1)
(D)
T_n = a + (n - 1) * d
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 30
Unanswered
In the arithmetic sequence (3, 7, 11, 15, ...), the common difference d and the 20th term (T_20) are respectively:
(A)
d = 4 and T_20 = 79
(B)
d = 5 and T_20 = 98
(C)
d = 3 and T_20 = 60
(D)
d = 4 and T_20 = 83
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 31
Unanswered
The sum of the first n terms of an arithmetic sequence (S_n) is formulated as:
(A)
S_n = n / 2 * [ 2a + (n - 1) * d ] = n / 2 * [ a + l ]
(B)
S_n = a * (1 - r^n) / (1 - r)
(C)
S_n = n * (a + d)
(D)
S_n = a / (1 - r)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 32
Unanswered
The common ratio r of the geometric sequence (64, 32, 16, 8, ...) is:
(A)
r = 1/2
(B)
r = -1/2
(C)
r = 4
(D)
r = 2
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 33
Unanswered
The sum to infinity (S_infinity) of a geometric series exists and converges if and only if the common ratio satisfies:
(A)
r = 1
(B)
r > 1
(C)
|r| < 1 (i.e. -1 < r < 1), and S_infinity = a / (1 - r)
(D)
|r| >= 2
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 34
Unanswered
The sum to infinity of the geometric series 12 + 6 + 3 + 1.5 + ... equals:
(A)
18
(B)
36
(C)
Infinity
(D)
24
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 35
Unanswered
If a, b, c form an arithmetic sequence, then the arithmetic mean b equals:
(A)
b = a + c
(B)
b = (a + c) / 2
(C)
b = sqrt(a * c)
(D)
b = 2 a c / (a + c)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 36
Unanswered
If a, b, c form a geometric sequence of positive real numbers, the geometric mean b equals:
(A)
b = + sqrt(a * c)
(B)
b = a * c
(C)
b = (a + c) / 2
(D)
b = a^2 + c^2
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 37
Unanswered
The sum of the first 10 terms of the geometric sequence 2, 6, 18, 54, ... equals:
(A)
118,096
(B)
29,524
(C)
59,048
(D)
19,682
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 38
Unanswered
The number of terms in the finite arithmetic sequence (5, 9, 13, ..., 81) is:
(A)
21 terms
(B)
19 terms
(C)
20 terms
(D)
25 terms
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 39
Unanswered
The 7th term of the geometric sequence (2, 6, 18, ...) is:
(A)
486
(B)
729
(C)
162
(D)
1458
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 40
Unanswered
If (x - 1, x + 2, 3x) form a geometric sequence, the positive value of x is:
(A)
2
(B)
6
(C)
3
(D)
4
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 41
Unanswered
The sum to infinity of the geometric series 16 + 8 + 4 + 2 + ... equals:
(A)
32
(B)
30
(C)
24
(D)
64
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 42
Unanswered
The derivative of f(x) = 4 x^3 - 5 x^2 + 7 x - 9 with respect to x is:
(A)
f'(x) = 12 x^3 - 10 x^2 + 7
(B)
f'(x) = 4 x^2 - 5 x + 7
(C)
f'(x) = 12 x^2 - 10 x
(D)
f'(x) = 12 x^2 - 10 x + 7
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 43
Unanswered
The slope of the tangent line to the curve y = x^2 - 6 x + 5 at the point (4, -3) equals:
(A)
m = -3
(B)
m = 2
(C)
m = -2
(D)
m = 8
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 44
Unanswered
If y = (2x + 1) * (3x - 4), then dy/dx evaluated at x = 1 equals:
(A)
-5
(B)
7
(C)
1
(D)
12
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 45
Unanswered
Using the Quotient Rule, the derivative of y = (x + 3) / (x - 2) for x != 2 is:
(A)
1 / (x - 2)^2
(B)
5 / (x - 2)^2
(C)
-5 / (x - 2)^2
(D)
(2x + 1) / (x - 2)^2
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 46
Unanswered
According to the Chain Rule, if y = (3 x^2 - 5)^4, then dy/dx is:
(A)
4 (3 x^2 - 5)^3
(B)
12 x (3 x^2 - 5)^4
(C)
6 x (3 x^2 - 5)^3
(D)
24 x (3 x^2 - 5)^3
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 47
Unanswered
The derivative of y = sin(3x) with respect to x is:
(A)
-3 cos(3x)
(B)
3 cos(3x)
(C)
3 sin(3x)
(D)
cos(3x)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 48
Unanswered
If a particle moves along a straight line such that its position s(t) = t^3 - 6 t^2 + 9 t meters, the particle comes to an instantaneous rest (velocity v(t) = 0) at times:
(A)
t = 0 seconds only
(B)
t = 6 seconds
(C)
t = 2 seconds and t = 4 seconds
(D)
t = 1 second and t = 3 seconds
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 49
Unanswered
The equation of the tangent line to the curve y = x^3 at the point (1, 1) is:
(A)
y = x
(B)
y = 3x - 2
(C)
y = 3x + 1
(D)
y = -3x + 4
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 50
Unanswered
The second derivative d^2y/dx^2 of the function y = x^4 - 2 x^3 + 5 is:
(A)
12 x^2 - 12 x
(B)
4 x^3 - 6 x^2
(C)
24 x - 12
(D)
12 x^2 - 6 x
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 51
Unanswered
If f(x) = |x - 3|, the derivative f'(3) at x = 3:
(A)
Equals 1
(B)
Equals -1
(C)
Does not exist because the left-hand derivative (-1) does not equal the right-hand derivative (+1)
(D)
Equals 0
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 52
Unanswered
If y = sin(3x) + cos(2x), then dy/dx at x = 0 equals:
(A)
3
(B)
1
(C)
5
(D)
-2
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 53
Unanswered
The slope of the tangent to the curve y = (x + 1)/(x - 1) at x = 2 is:
(A)
-2
(B)
3
(C)
-1
(D)
2
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 54
Unanswered
If the tangent to y = x^2 - 4x + 5 is parallel to the x-axis, the point of tangency is:
(A)
(2, 0)
(B)
(2, 1)
(C)
(4, 5)
(D)
(0, 5)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Mathematics curriculum.
Question 55
Unanswered
The hydrostatic pressure exerted by a static homogeneous liquid of density rho at depth h beneath its free surface is expressed by:
(A)
P = rho * h / g
(B)
P = 1/2 rho * g * h^2
(C)
P = rho * g / h
(D)
P = rho * g * h
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 56
Unanswered
A diver descends to a depth of 30 meters in seawater (density = 1030 kg/m^3). If atmospheric pressure is 1.013 x 10^5 Pa and g = 9.8 m/s^2, the total absolute pressure experienced by the diver is approximately:
(A)
4.04 x 10^5 Pa (approx. 4.0 atmospheres)
(B)
6.06 x 10^5 Pa
(C)
1.01 x 10^5 Pa
(D)
3.03 x 10^5 Pa
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 57
Unanswered
Pascal's principle states that when pressure is applied to an enclosed, incompressible fluid, it is transmitted:
(A)
Undiminished to every portion of the fluid and to the walls of the containing vessel
(B)
Only downwards towards the bottom of the vessel
(C)
With an exponential decay as distance increases
(D)
Strictly to compressible gases
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 58
Unanswered
In a hydraulic press, the ratio of the cross-sectional area of the large piston to that of the small piston is 50. If a force of 100 N is exerted on the small piston, the maximum force exerted by the large piston is:
(A)
2500 N
(B)
50,000 N
(C)
5000 N
(D)
2 N
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 59
Unanswered
The mechanical advantage (eta) of an ideal hydraulic press equals all of the following ratios EXCEPT:
(A)
Area of the large piston / Area of the small piston (A / a)
(B)
Force on the large piston / Force on the small piston (F / f)
(C)
Work done by the large piston / Work done on the small piston > 1
(D)
Distance moved by the small piston / Distance moved by the large piston (y1 / y2)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 60
Unanswered
The relative density (specific gravity) of a substance is defined as:
(A)
The mass of the substance divided by its volume at 100°C
(B)
The ratio of the density of the substance to the density of pure water at 4°C
(C)
The reciprocal of the buoyant force
(D)
The product of density and the acceleration due to gravity
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 61
Unanswered
In a U-tube manometer containing two immiscible liquids in equilibrium, the heights of the liquid columns measured above the separating surface are:
(A)
Directly proportional to their densities
(B)
Equal regardless of the liquids used
(C)
Proportional to the square of the cross-sectional area of the tube
(D)
Inversely proportional to their respective densities (h1 / h2 = rho2 / rho1)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 62
Unanswered
Why are hydroelectric storage dams constructed with a base that is significantly thicker than the crest?
(A)
To prevent solar radiation from penetrating the foundation
(B)
To allow fish to swim upstream through drainage gates
(C)
Because hydrostatic water pressure increases linearly with depth (P = rho * g * h), exerting immense overturning forces at the bottom
(D)
To reduce the gravitational pull of the bedrock
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 63
Unanswered
A metallic cube of side length 10 cm and density 7800 kg/m^3 is completely submerged in water (density 1000 kg/m^3). The buoyant force (upthrust) acting on the cube is (g = 10 m/s^2):
(A)
68 N
(B)
100 N
(C)
78 N
(D)
10 N
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 64
Unanswered
Pure water reaches its maximum density (1.000 g/cm^3 or 1000 kg/m^3) at a temperature of:
(A)
4.0 °C
(B)
0.0 °C
(C)
-4.0 °C
(D)
25.0 °C
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 65
Unanswered
In a hydraulic press, if the radius of the large piston is 4 times that of the small piston, the mechanical advantage is:
(A)
4
(B)
16
(C)
2
(D)
8
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 66
Unanswered
A mercury manometer connected to a gas tank shows the mercury level in the free arm is 4 cm higher than the gas arm (Pa = 76 cm Hg). The gas pressure is:
(A)
4 cm Hg
(B)
72 cm Hg
(C)
80 cm Hg
(D)
76 cm Hg
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 67
Unanswered
A U-tube contains water (ρ = 1000 kg/m³) and oil (ρ = 800 kg/m³). If the oil column height above the interface is 10 cm, the balancing water column height is:
(A)
10 cm
(B)
6.4 cm
(C)
12.5 cm
(D)
8 cm
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 68
Unanswered
Boyle's Law states that for a fixed mass of an ideal gas kept at constant temperature, the volume V is:
(A)
Directly proportional to pressure
(B)
Independent of pressure changes
(C)
Inversely proportional to its absolute pressure P (P1 * V1 = P2 * V2)
(D)
Directly proportional to absolute temperature
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 69
Unanswered
Charles's Law establishes that at constant pressure, the volume of a given mass of gas is directly proportional to its:
(A)
Celsius temperature only
(B)
Square of the absolute temperature
(C)
Atmospheric density
(D)
Absolute temperature in Kelvin (T_K = t_C + 273.15)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 70
Unanswered
The volume expansion coefficient at constant pressure (alpha_v) and the pressure expansion coefficient at constant volume (beta_p) for all ideal gases have the universal constant value of:
(A)
1 / 273.15 K^-1 (approx. 0.00366 K^-1)
(B)
8.314 J/(mol.K)
(C)
1.013 x 10^5 Pa
(D)
273.15 K
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 71
Unanswered
Absolute zero temperature (0 Kelvin or -273.15 °C) is defined physically as the theoretical temperature at which:
(A)
The volume and pressure of an ideal gas theoretically extrapolate to zero and translational molecular motion reaches its quantum minimum
(B)
All liquids solidify into glass
(C)
Water reaches its maximum density
(D)
Atmospheric air completely combusts
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 72
Unanswered
The Ideal Gas Law combining all empirical gas relationships is mathematically formulated as:
(A)
P / V = n * R * T
(B)
P * T = n * R * V
(C)
P * V = n * R * T
(D)
P * V = m * g * h
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 73
Unanswered
A gas cylinder contains 10 liters of gas at a pressure of 3.0 atm. If the volume is reduced to 2.5 liters at constant temperature, the new pressure inside the cylinder will be:
(A)
12.0 atm
(B)
6.0 atm
(C)
1.2 atm
(D)
7.5 atm
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 74
Unanswered
When a gas trapped inside a rigid container of fixed volume is heated from 27 °C (300 K) to 127 °C (400 K), its pressure increases by a factor of:
(A)
127 / 27
(B)
16 / 9
(C)
2 times
(D)
4 / 3 (since P1 / T1 = P2 / T2)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 75
Unanswered
The universal gas constant R in SI units has the numerical value and dimensions of:
(A)
1.38 x 10^-23 Pa . m^3
(B)
8.314 J / (mol . K)
(C)
0.0821 J / mol
(D)
6.022 x 10^23 J / K
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 76
Unanswered
An air bubble released from the bottom of a deep lake expands in volume as it rises towards the surface because:
(A)
The hydrostatic pressure decreases as depth decreases, allowing the trapped air to expand according to Boyle's law
(B)
The bubble absorbs water molecules into its gas phase
(C)
The water temperature at the surface is near absolute zero
(D)
Atmospheric pressure increases at the surface
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 77
Unanswered
Real gases behave most closely to an ideal gas under conditions of:
(A)
Very low pressure and high temperature (where intermolecular attraction forces and molecular volumes become negligible)
(B)
Zero gravitational acceleration
(C)
High pressure and near liquefaction point
(D)
Extremely high pressure and low temperature
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 78
Unanswered
A fixed quantity of an ideal gas has a volume of 600 cm^3 at 27 °C. If the gas is heated to 127 °C under constant pressure, its new volume will be:
(A)
700 cm^3
(B)
1200 cm^3
(C)
800 cm^3
(D)
900 cm^3
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 79
Unanswered
The pressure of a gas trapped inside an incandescent light bulb is 0.8 atm at room temperature (27 °C). When the bulb operates, the filament heats the gas to 327 °C at constant volume. The operational pressure is:
(A)
1.6 atm
(B)
1.2 atm
(C)
0.96 atm
(D)
2.4 atm
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 80
Unanswered
If both the absolute temperature and the absolute pressure of a confined ideal gas are doubled, the volume of the gas:
(A)
Doubles to twice its original volume
(B)
Quadruples
(C)
Decreases to one-fourth
(D)
Remains constant and unchanged
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 81
Unanswered
The density of an ideal gas at temperature T and pressure P is rho. If the pressure is tripled and the absolute temperature is halved, the new density becomes:
(A)
1.5 rho
(B)
6 rho (since rho is proportional to P / T)
(C)
0.67 rho
(D)
3 rho
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 82
Unanswered
The volume expansion coefficient at constant pressure (alpha_v) of an ideal gas is physically measured using:
(A)
A torsion balance
(B)
A hydrometer
(C)
A venturi meter and manometer
(D)
Joly's bulb apparatus or Charles's apparatus with a dry mercury droplet index
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Physics curriculum.
Question 83
Unanswered
An ionic bond is formed primarily between:
(A)
Noble gas atoms at very low temperatures
(B)
A metal atom that loses electrons forming a cation and a non-metal atom that gains electrons forming an anion due to electrostatic attraction
(C)
Two non-metal atoms sharing pairs of valence electrons equally
(D)
Positive metal ions immersed in a sea of delocalized electrons
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 84
Unanswered
Which of the following compounds exhibits polar covalent bonding due to a significant difference in electronegativity between 0.4 and 1.7?
(A)
Water (H2O)
(B)
Methane (CH4)
(C)
Chlorine gas (Cl2)
(D)
Sodium chloride (NaCl)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 85
Unanswered
The nitrogen molecule (N2) contains a:
(A)
Double covalent bond
(B)
Single ionic bond
(C)
Triple covalent bond (one sigma bond and two pi bonds) sharing 3 electron pairs
(D)
Coordinate dative bond
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 86
Unanswered
Solid ionic compounds such as crystal NaCl do NOT conduct electricity in the solid state because:
(A)
Electrons are moving too rapidly
(B)
They decompose in the presence of air
(C)
They contain no electrical charges
(D)
Their ions are tightly locked in fixed positions within the rigid crystal lattice and cannot move freely
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 87
Unanswered
A metallic bond is physically described as the electrostatic attraction between:
(A)
Dipole molecules in a polar liquid
(B)
Positive metal cations in the crystal lattice and the mobile sea of delocalized valence electrons
(C)
Protons and neutrons in the nucleus
(D)
Positive ions and negative non-metal anions
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 88
Unanswered
Acids are chemical compounds that dissociate in aqueous solutions to produce:
(A)
Sodium ions and chlorine gas
(B)
Precipitated metallic salts
(C)
Hydroxide ions (OH-) turning red litmus paper blue
(D)
Hydrogen ions (H+ or hydronium ions H3O+), turning blue litmus paper red
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 89
Unanswered
The chemical formula of aluminum sulfate is correctly written as:
(A)
Al(SO4)3
(B)
Al2(SO4)3
(C)
AlSO4
(D)
Al3(SO4)2
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 90
Unanswered
Which of the following oxides is classified as an amphoteric oxide that reacts with both acids and bases to yield salt and water?
(A)
Aluminum oxide (Al2O3)
(B)
Sodium oxide (Na2O)
(C)
Carbon dioxide (CO2)
(D)
Sulfur trioxide (SO3)
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 91
Unanswered
The reaction between an acid and a base to produce a salt and water is known as a:
(A)
Neutralization reaction
(B)
Polymerization reaction
(C)
Thermal decomposition reaction
(D)
Combustion reaction
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 92
Unanswered
A solution with a pH value of 3.0 is classified as:
(A)
Weakly basic
(B)
Neutral
(C)
Strongly acidic
(D)
Strongly alkaline
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 93
Unanswered
Which of the following solutions has the lowest pH value (strongest acidity) at equal concentration?
(A)
CH3COOH
(B)
NH4OH
(C)
NaCl
(D)
HCl
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 94
Unanswered
Phenolphthalein indicator cannot distinguish between an acidic solution and a neutral solution because:
(A)
It is colorless in both
(B)
It precipitates in both
(C)
It is red in both
(D)
It is blue in both
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 95
Unanswered
Which of the following oxides is amphoteric?
(A)
SO3
(B)
Na2O
(C)
ZnO
(D)
MgO
Official Scientific Justification: An accurate model answer extracted from the Ministry’s latest books 2026/2027 for the Science curriculum.
Question 96
Unanswered
According to the 2026/2027 Egyptian STEM biology syllabus, what is the exact scientific deduction regarding: Chargaff's Rules of DNA Base Pairing?
(A)
Adenine bonds with Guanine via three hydrogen bonds
(B)
The percentage of %A + %T always equals 50% in all organisms
(C)
Uracil replaces Thymine in the double helix of nuclear DNA
(D)
In any double-stranded DNA molecule, the percentage of Adenine equals Thymine (%A = %T) and Guanine equals Cytosine (%G = %C), with purines equaling pyrimidines
Official Scientific Justification: Chargaff established that complementary base pairing in double-stranded DNA requires A to pair with T (2 hydrogen bonds) and G to pair with C (3 hydrogen bonds).
Question 97
Unanswered
The ion directly responsible for the explosion of synaptic vesicles and the release of acetylcholine in the neuromuscular synapse cleft is:
(A)
Potassium ion K⁺
(B)
Sodium ion Na⁺
(C)
Calcium ion Ca²⁺
(D)
Chloride ion Cl⁻
Official Scientific Justification: Entry of calcium ions through presynaptic membrane pumps leads to the fusion of neuronal vesicles and the release of acetylcholine into the synaptic cleft.
Question 98
Unanswered
The movement of tension in the tendrils of climbing plants such as peas and grapes depends physiologically on:
(A)
Water loss through rapid transpiration
(B)
Degeneration of tendril cells
(C)
Secretion of gluey substances
(D)
Slow growth of the area in contact with the support and rapid growth of the area far from it as a result of the varying distribution of auxins
Official Scientific Justification: The touch of the tendril with the support causes the auxins to migrate to the far side, which quickly elongates, and the tendril rotates around the support, and the stem straightens vertically.
Question 99
Unanswered
Rotational cytoplasmic movement inside living plant cells (such as Elodea plants) is indicated by:
(A)
Stomata open
(B)
Movement of chloroplasts immersed in the cytoplasm stream in a constant rotational direction
(C)
Change in cell wall thickness
(D)
Mitochondrial division
Official Scientific Justification: The cytoplasm is colorless, and its rotational flow is inferred by observing the movement of chloroplasts carried in its flow under a microscope.
Question 100
Unanswered
The movement of hydrotropism in plant roots is considered tropism:
(A)
Positive (the root bends in the direction of moisture and water concentration)
(B)
Negatively
(C)
Unaffected
(D)
randomly
Official Scientific Justification: Plant roots always move towards sources of moisture and water in the soil. The root is positive for hydrotropism, positive for terrestrial tropism, and negative for phototropism.
Question 101
Unanswered
The pulling movement occurs in bulbs and corms (such as carcasses and daffodils) with the aim of:
(A)
Pull the stored ground leg down to an appropriate level from the soil surface to secure and support it against the wind
(B)
Getting rid of carbon dioxide
(C)
Light absorption for photosynthesis
(D)
Repel terrestrial insects
Official Scientific Justification: The tough roots shrink and their lengths decrease, causing the bulb or corm to descend to a suitable depth below the surface of the earth to protect its aerial parts against the wind.
Question 102
Unanswered
The hormone that affects both glandular and non-glandular tissue in the adult female body is:
(A)
Calcitonin hormone
(B)
Oxytocin
(C)
Growth hormone
(D)
Aldosterone hormone
Official Scientific Justification: Oxytocin affects the smooth muscles of the uterus (non-glandular tissue) to induce labor, and affects the mammary glands (glandular tissue) to produce milk.
Question 103
Unanswered
The hormone responsible for maintaining the balance of minerals in the blood by stimulating the reabsorption of sodium ions and eliminating excess potassium through the kidneys is:
(A)
Cortisol hormone
(B)
Thyroxine hormone
(C)
Insulin hormone
(D)
Aldosterone
Official Scientific Justification: Aldosterone is secreted by the adrenal cortex and regulates minerals by reabsorbing sodium and excreting potassium in the urine.
Question 104
Unanswered
The direct cause of myxedema in an adult is:
(A)
Severe deficiency in thyroxine secretion in adulthood
(B)
Insulin deficiency
(C)
Hyperactivity of the parathyroid gland
(D)
Excessive increase in growth hormone
Official Scientific Justification: Myxedema results from a severe decline in thyroid function and thyroxine deficiency in adults, and leads to dry skin, hair loss, mental dullness, and decreased energy levels.Z.
Question 105
Unanswered
The gland that secretes both external ductal secretion and non-ductal hormonal secretion directly into the blood is:
(A)
Thyroid gland
(B)
pituitary gland
(C)
Pancreas (common/mixed gland)
(D)
Adrenal gland
Official Scientific Justification: The pancreas is a common gland that secretes digestive juices through the pancreatic duct and secretes the hormones insulin and glucagon directly into the bloodstream.
Question 106
Unanswered
A hormone secreted from the anterior lobe of the pituitary gland that stimulates the growth of Graafian follicles in the female ovary and the production of sperm in the male testicle is:
(A)
follicle stimulating hormone (FSH)
(B)
ACTH hormone
(C)
Prolactin hormone
(D)
Luteinizing hormone (LH)
Official Scientific Justification: FSH It stimulates the growth and maturation of estrogen-secreting Graafian follicles in the female, and stimulates the formation of seminiferous tubules and sperm in the male.
Question 107
Unanswered
Antidiuretic hormone (ADH/vasopressin) works to raise blood pressure by:
(A)
Expansion of the arteries
(B)
Stimulate sweat
(C)
Sodium excretion in urine
(D)
Smooth blood vessel constriction and water reabsorption in nephrons
Official Scientific Justification: ADH It reduces the amount of urine by reabsorbing water in the renal tubules, and contracts the smooth muscles in the walls of blood vessels, which raises blood pressure.
Question 108
Unanswered
The pituitary gland is considered the master of the endocrine glands (the maestro) because:
(A)
The largest gland by weight
(B)
It secretes stimulating hormones that control the secretions of most other endocrine glands in the body, such as the thyroid, adrenals, and gonads
(C)
Connected to the liver
(D)
Secretes digestive enzymes
Official Scientific Justification: Its anterior lobe secretes TSH, ACTH, FSH, and LH, which stimulate the thyroid, adrenal cortex, and gonads, thus directing the endocrine system precisely.
Question 109
Unanswered
Which of the following hormones is considered a steroid hormone (derived from fat and cholesterol)?
(A)
Growth hormone (GH)
(B)
Thyroxine
(C)
Progesterone and testosterone
(D)
Insulin
Official Scientific Justification: Adrenal cortex hormones and gonadal hormones (estrogen, progesterone, testosterone) are fatty steroid compounds that penetrate through cellular membranes.
Question 110
Unanswered
The adrenal medulla is stimulated to secrete the emergency hormones adrenaline and noradrenaline via:
(A)
Rapid and direct sympathetic nervous stimulation in cases of fear, fight, and flight
(B)
Body temperature change
(C)
High blood sugar
(D)
ACTH hormonal stimulation
Official Scientific Justification: The adrenal medulla is nervous in origin, and responds to sympathetic nerve fibers in fractions of a second to raise blood pressure, heart rate, and emergency glucose.
Question 111
Unanswered
When severe dehydration and decreased blood volume and body fluids occur, which of the following hormonal changes occur?
(A)
Thyroxine secretion stops
(B)
ADH decreases and insulin increases
(C)
The secretion of ADH and aldosterone increases to restore water and salts
(D)
Calcitonin secretion increases
Official Scientific Justification: In response to fluid deficiency, the hypothalamus is activated to secrete ADH to retain water, and the adrenal cortex secretes aldosterone to retain sodium to maintain volume and pressure.
Question 112
Unanswered
The hormone that is secreted from the stomach lining and travels through the blood to return to the same stomach, stimulating it to secrete its digestive gastric juices, is:
(A)
Secretin hormone
(B)
Pepsin hormone
(C)
Gastrin hormone
(D)
Cholecystokinin hormone
Official Scientific Justification: Gastrin is secreted from G cells in the gastric mucosa and travels through the blood circulation to return and stimulate the stomach glands to secrete HCl and pepsinogen.
Question 113
Unanswered
The two hormones that are secreted from the mucous membrane of the small intestine to stimulate the pancreas to secrete its digestive juices are:
(A)
Insulin and glucagon
(B)
Thyroxine and calcitonin
(C)
Prolactin and oxytocin
(D)
Secretin and cholecystokinin (Secretin & CCK)
Official Scientific Justification: Starling discovered that the introduction of food into the intestine stimulates the secretion of secretin and cholecystokinin, which travel in the blood to stimulate pancreatic ductal secretion.
Question 114
Unanswered
When examining a patient who suffers from severe weight loss, bulging eyes, rapid heart rate, and high temperature, the doctor diagnoses the condition as:
(A)
Myxedema
(B)
Exophthalmos caused by excessive secretion of the hormone thyroxine
(C)
Diabetic urine
(D)
Dwarfism
Official Scientific Justification: Proptosis (Graves' disease) results from excessive thyroxine secretion, increased metabolic and oxidative rates, and severe weight loss with bulging eyes.
Question 115
Unanswered
Beta cells in the islets of Langerhans in the pancreas are responsible for secreting the hormone:
(A)
Insulin
(B)
Glucagon
(C)
Somatostatin
(D)
Pepsin
Official Scientific Justification: Beta cells represent the majority of cells in the islets of Langerhans and secrete insulin to reduce glucose by entering the cells and converting it into glycogen and fat.
Question 116
Unanswered
Which of the following conditions leads to increased secretion of parathormone from the parathyroid glands?
(A)
High blood calcium level
(B)
Low phosphate
(C)
Excessive vitamin D excess
(D)
Low level of ionized calcium in blood plasma
Official Scientific Justification: Hypocalcemia is a direct stimulus for the parathyroid glands to secrete parathormone to withdraw calcium from the bones and reabsorb it into the kidneys.
Question 117
Unanswered
Auxins in plants (such as indole acetic acid (IAA)) are chemicals secreted from:
(A)
Dead wood cells
(B)
Cork cells
(C)
The growing tops and live plant buds are active and move to the response areas
(D)
Pollen granules only
Official Scientific Justification: Auxins are plant hormonal substances produced by growing shoots and young shoots and transmitted by diffusion to regulate and direct the growth and elongation of plant cells.
Question 118
Unanswered
Which of the following hormones is secreted by the pituitary gland and indirectly affects basic metabolic processes and the speed of oxygen consumption?
(A)
Insulin hormone
(B)
Thyroid stimulating hormone (TSH).
(C)
The hormone oxytocin
(D)
ADH hormone
Official Scientific Justification: TSH It stimulates the secretion of thyroxine from the thyroid gland, and thyroxine is the primary regulator of the body's basal metabolic rate.
Question 119
Unanswered
The cells that secrete the hormones oxytocin and ADH and store them in the posterior lobe of the pituitary gland are:
(A)
Apocrine neurons in the hypothalamus (hypothalamus)
(B)
Glial cells
(C)
Frontal lobe glandular cells
(D)
Pineal gland cells
Official Scientific Justification: The posterior lobe is a storehouse of nerves; Hormones are made in the bodies of nerve cells secreted by the hypothalamus and transported through the axons to be secreted into the blood.
Question 120
Unanswered
The salivary glands and sweat glands in the human body are examples of:
(A)
Exocrine ductal glands discharge their secretions through special channels outside the bloodstream
(B)
Common glands
(C)
Steroid tissue
(D)
Aductal endocrine glands
Official Scientific Justification: The ductal glands have channels through which they secrete their digestive or excretory substances, either outside the body, such as sweat, or inside cavities, such as salivary juice.
Question 121
Unanswered
What is the direct physiological effect of injecting a healthy person with an excessive dose of the hormone insulin?
(A)
A sharp increase in blood sugar
(B)
A severe drop in blood glucose levels (hypoglycemia) and hypoglycemic coma
(C)
Increased urine secretion
(D)
Uric acid accumulation
Official Scientific Justification: Excess insulin brings all the glucose into the cells, depriving the brain cells of their vital energy source and leading to dizziness and a dangerous hypoglycemic coma.
Question 122
Unanswered
Plant hormones are responsible for the phenomenon of leaf fall and fruit ripening and falling. Where the role of a hormonal gas increases:
(A)
Gibberellic acid
(B)
Abscisic acid
(C)
Ethylene gas
(D)
Auxin IAA
Official Scientific Justification: Ethylene is a gaseous hormone secreted by the plant to stimulate the ripening of fruits and the formation of the separation layer that leads to the fall of leaves and ripe fruits.
Question 123
Unanswered
The lymphocytes responsible for secreting specific antibodies in humoral immunity are:
(A)
Plasma B cells
(B)
Macrophages
(C)
Natural killer (NK) cells
(D)
Helper T cells (TH)
Official Scientific Justification: Activated B cells differentiate into plasma B cells that secrete thousands of specialized antibodies per second.
Question 124
Unanswered
Immunoglobulin (antibody), which exists as a pentamer and contains 10 sites to bind to the antigen is:
(A)
IgM
(B)
IgA
(C)
IgG
(D)
IgE
Official Scientific Justification: IgM It is the largest antibody and consists of 5 subunits linked together by a J chain and has 10 binding sites, which makes it extremely efficient in binding.
Question 125
Unanswered
Immune chemicals secreted by virus-infected cells to warn neighboring healthy cells to produce enzymes that inhibit virus replication.S is:
(A)
Chemokines
(B)
Complements
(C)
Interleukins
(D)
Interferons
Official Scientific Justification: Interferons are defense proteins secreted by virus-infected cells and transmitted to healthy cells to stimulate them to stop replication of viral DNA.
Question 126
Unanswered
Cells that carry CD8 receptors and directly eliminate cancer cells, virus-infected cells, and transplanted organs are:
(A)
Helper T cells (Th)
(B)
Memory B cells
(C)
Mast cells
(D)
Cytotoxic T cells
Official Scientific Justification: Cytotoxic T cells possess CD8 receptors and secrete the membrane-perforin protein perforin and apoptosis-inducing lymphotoxins.
Question 127
Unanswered
Peyer's spots's Patches) Tiny lymph nodes spread in the mucous membrane lining the:
(A)
Pharynx
(B)
Lower part of the small intestine (ileum)
(C)
Stomach
(D)
esophagus
Official Scientific Justification: Peyer's patches are lymph nodes clustered in the lining of the ileum that play a crucial immunological role in eliminating intestinal microbes introduced with food.
Question 128
Unanswered
Which of the following amino acids is considered a non-protein acid produced by plants as protective and toxic substances for microorganisms?
(A)
Canavanine and cephalosporin
(B)
Valine and leucine
(C)
Methionine and tryptophan
(D)
Glycine and alanine
Official Scientific Justification: Canavanine and cephalosporin are non-protein amino acids that are not involved in protein synthesis, but they act as toxic substances that kill invading microbes.
Question 129
Unanswered
The chemical compound secreted by mast cells and basal white blood cells that is responsible for the widening of blood vessels and symptoms of inflammation is:
(A)
Heparin
(B)
Interleukin
(C)
Histamine
(D)
Albumin
Official Scientific Justification: Histamine is a powerful vasodilator that is secreted into the area of injury to increase capillary permeability and the flow of blood plasma and white blood cells to the wound site.
Question 130
Unanswered
The protein secreted by cytotoxic T cells (Tc) that creates holes in the plasma membrane of the target cell is:
(A)
Perforin protein
(B)
Complement C3
(C)
Interleukin
(D)
globulin
Official Scientific Justification: Perforin is a hole-maker protein. It is secreted to integrate with the membrane of the affected cell and puncture it, causing the entry of water and salts and causing it to explode.
Question 131
Unanswered
The cells that suppress and inhibit the immune response after eliminating the microbe and secrete lymphokine proteins are:
(A)
Suppressor T cells
(B)
Neutrophil cells
(C)
Plasma cells
(D)
Helper T cells (Th)
Official Scientific Justification: Ts cells carry CD8 receptors and secrete lymphokines to stop the production of antibodies and lead to the death of most activated T and B cells.
Question 132
Unanswered
In the secondary immune response upon exposure to the microbe for the second time, the response is characterized as:
(A)
Rely only on the first line of defense
(B)
Slow and takes days
(C)
It is very rapid and produces huge amounts of antibodies thanks to memory cells, and the individual does not show symptoms of the disease
(D)
Limited to non-specialized immunity
Official Scientific Justification: Memory B and T cells store antigen information for decades, and when infection is repeated, they divide immediately and eliminate the microbe before symptoms appear.
Question 133
Unanswered
The covalent chemical bond that connects the heavy and light peptide chains in an antibody molecule is:
(A)
Additional peptide bonds
(B)
Ionic bonds
(C)
Disulfide Bonds - S-S
(D)
Weak hydrogen bonds
Official Scientific Justification: The heavy chains are linked to the light and to each other by strong double disulfide bonds that give the antibody its characteristic stereoisomer (Y) shape.
Question 134
Unanswered
The lymphatic organ, which is called the graveyard of old and worn-out red blood cells and contains large numbers of macrophages, is:
(A)
Thymus gland
(B)
Tonsils
(C)
appendix
(D)
Spleen
Official Scientific Justification: The spleen purifies the blood from foreign bodies and breaks down aging red blood cells into their primary components (hemoglobin and iron) for recycling.
Question 135
Unanswered
The major histocompatibility complex (MHC) protein associates within the macrophage cell with:
(A)
Perforin protein
(B)
Microbe antigen after being broken down by lysosomal enzymes to be displayed on the external surface
(C)
Secreted antibodies
(D)
Histamine molecules
Official Scientific Justification: Macrophages engulf the microbe, break it down with lysosomes, and bind its fragments to the MHC protein to display the compound on their membrane for recognition by TH cells via the CD4 receptor.
Question 136
Unanswered
Substances secreted by T helper cells (Th) and acting as a communication tool to activate neighboring B and T cells are:
(A)
Antibodies
(B)
Hemoglobin
(C)
Myoglobin
(D)
Interleukins
Official Scientific Justification: Interleukins are mediators of communication between immune cells. They activate B cells to divide and differentiate into plasma cells, and stimulate other immune cells.
Question 137
Unanswered
The antibody that is transferred across the placenta from the blood of the pregnant mother to the blood of the fetus to give it natural, passive, acquired immunity is:
(A)
IgM
(B)
IgG
(C)
IgD
(D)
IgE
Official Scientific Justification: IgG It is the only antibody capable of crossing the placenta due to its small size, providing passive immune protection to the fetus and newborn for several months.
Question 138
Unanswered
The method of action of antibodies that is considered the most appropriate and most efficient in inactivating viruses and preventing their penetration into cells is:
(A)
Deposition method
(B)
Decomposition method
(C)
Neutralization method
(D)
Alignment method
Official Scientific Justification: Neutralization neutralizes viruses by binding to their outer envelopes to prevent them from attaching to the intact cell membrane, or trapping genetic material within the envelope.
Question 139
Unanswered
Complements are a group of plasma proteins that activate when an antibody binds to an antigen and work to:
(A)
Decomposing the antigenic envelope and dissolving its contents to facilitate their ingestion by macrophages
(B)
Histamine secretion
(C)
Activate viruses
(D)
Blood clotting
Official Scientific Justification: Complements bind to the attachment site on the heavy chain of the antibody, puncture the wall of the microbe, and degrade it, making it an accessible prey for phagocytic cells.
Question 140
Unanswered
Plant hypersensitivity is an effective immunological method that includes:
(A)
Secreting nectar to attract bees
(B)
Stomata open at night
(C)
Root loss
(D)
The plant kills some of its infected tissues and cells locally to prevent the spread of the microbe to healthy tissues
Official Scientific Justification: The plant deliberately sacrifices and kills the cells surrounding the area of infection to deprive the microbe (especially the obligate fungi) of food, so it dies in its place.
Question 141
Unanswered
Natural killer (NK) cells attack and kill cancer cells and virus-infected cells by:
(A)
Secretion of antibodies
(B)
Secretion of specialized digestive enzymes without the need for prior specific antigen recognition
(C)
Swallow the cells whole
(D)
Histamine secretion
Official Scientific Justification: NK cells are part of non-specific innate immunity, attacking tumors and virus-infected cells and secreting lytic enzymes that directly eliminate them.
Question 142
Unanswered
The surface immune receptor characteristic of T helper cells (Th) that enables them to recognize the antigen complex with the MHC protein is:
(A)
CD8 receptor
(B)
CD3 receptor
(C)
BCR receptor
(D)
CD4 receptor
Official Scientific Justification: Th cells carry on their surface the CD4 receptor that specifically binds to the antigen + MHC complex displayed on the surface of the macrophage or B cell.
Question 143
Unanswered
Vaccination gives humans immunity:
(A)
Acquired long-term positivity for the formation of memory cells
(B)
Temporary negativity that disappears within weeks
(C)
Innate, inherited
(D)
Not specialized
Official Scientific Justification: The vaccine is a dead or weakened microbe that trains the immune system to produce antibodies and memory cells that remain for decades without infecting the individual with the disease.
Question 144
Unanswered
Injection with serum (Antiserum) containing ready-made antibodies to neutralize scorpion venom gives the patient immunity:
(A)
A rapid and temporary acquired negativity that is not accompanied by memory cells
(B)
Innate
(C)
Cellular induced
(D)
Lasting positivity
Official Scientific Justification: The serum provides immediate, rapid protection by neutralizing toxins with ready-made antibodies, but it disappears from the body and does not leave immune memory cells.
Question 145
Unanswered
Which of the following immune structures represents the first line of defense in the human body to prevent the entry of pathogens?
(A)
Intact skin with its stratum corneum, mucus, HCl in the stomach, and saliva saturated with lysozyme
(B)
Toxic T cells
(C)
Antibodies
(D)
Macrophages
Official Scientific Justification: The first line of defense is physical, chemical and mechanical barriers that prevent microbes from penetrating the internal tissues of the body.
Question 146
Unanswered
The enzymes secreted by the plant to break down bacterial toxins and convert them into non-toxic compounds are:
(A)
Detoxifying enzymes
(B)
pepsin enzymes
(C)
RNA polymerase enzymes
(D)
Palace enzymes
Official Scientific Justification: Detoxification enzymes are immune proteins produced by plants that react with toxins from invading microbes, neutralize them, and protect tissues.
Question 147
Unanswered
Monocytes are functionally capable of leaving the bloodstream when needed:
(A)
Transformation into B cells
(B)
Transform into active macrophages to engulf microbes and cellular debris
(C)
Antibody formation
(D)
Histamine secretion
Official Scientific Justification: Mononuclear cells circulate in the blood, and when they reach infected tissues, they differentiate and turn into large phagocytic cells to fight infection.
Question 148
Unanswered
Lymphotoxins secreted by cytotoxic T cells (Tc) eliminate the infected cell by:
(A)
Immunosuppression
(B)
Calcium withdrawal
(C)
Blood plasma coagulation
(D)
Activation of certain genes within the nucleus of the infected cell, which leads to the fragmentation of its genetic material and its programmed death (Apoptosis).
Official Scientific Justification: Lymphotoxins penetrate the nucleus of the infected cell and stimulate self-destruction and DNA fragmentation, so the viral or cancerous cell commits suicide and disappears.
Question 149
Unanswered
The substance that the plant secretes to close wounds in its woody stems and completely isolate the affected tissue from the air and microbes is:
(A)
Gum and cork
(B)
Ascorbic acid
(C)
Monosaccharides
(D)
Liquid auxins
Official Scientific Justification: Deposition of mucilage around wound sites and cork formation insulates internal plant tissues and prevents the entry of invasive fungi and bacteria.
Question 150
Unanswered
The phenomenon of natural parthenogenesis in honey bees results in:
(A)
Fertile queens (2N)
(B)
Female workers only
(C)
Bees are always male, and their somatic cells are haploid (1N) resulting from an unfertilized egg that grows mitotically.
(D)
Diploid males
Official Scientific Justification: The queen bee lays unfertilized eggs (N) that grow through natural parthenogenesis without fertilization to produce male bees (N), while fertilized eggs (2N) give females (queens and stags).machines).
Question 151
Unanswered
Reproduction by peaceful association in two adjacent threads of the spirogyra moss (Rem al-Barak) occurs in the case of:
(A)
Mild spring
(B)
Complete darkness
(C)
The environment is exposed to drought, change in water purity, or change in temperature (unsuitable conditions)
(D)
Abundance of pure fresh water
Official Scientific Justification: Spirogyra resorts to sexual reproduction by peaceful or lateral pairing to withstand harsh conditions and form zygospores (2N bacterial inoculum) surrounded by a thick wall.
Question 152
Unanswered
In the life cycle of the fougere plant (a fern), the haploid (N) gametophyte produces its male and female gametes by:
(A)
Mitosis within antheridia and archegonia
(B)
Direct meiosis
(C)
Surface budding
(D)
Regeneration
Official Scientific Justification: The fougere gametophyte is originally haploid (N), so its ciliated swimmers are formed inside the antheridia and its eggs are formed inside the archegonia by mitotic division.like.
Question 153
Unanswered
The apple is considered a false fruit from a morphological and anatomical perspective because:
(A)
It is made without seeds
(B)
The cup leaves become greasy
(C)
The edible, fatty part that is lubricated by food is the takht, not the ovary of the flower
(D)
Produced from a hermaphrodite flower
Official Scientific Justification: A false fruit is any fruit in which any part other than the ovary is saturated with food; In apples, the pink stem swells and becomes the edible part.
Question 154
Unanswered
Double fertilization in flowering plants involves two fusions:
(A)
The fusion of two pollen grains with one egg
(B)
Fusion of petals with sepals
(C)
Chromosome duplication in Takht cells
(D)
The fusion of the zygote nucleus (N) with the egg nucleus (N) to form the zygote (2N), and the fusion of the second nuclei (N) with the two polar nuclei (2N) to form the sperm nucleus.Dosperm (3N)
Official Scientific Justification: Double fertilization is a distinctive feature of the angiosperms: fertilization of the egg to form the embryo, and triple fusion to form the endosperm (3N).
Question 155
Unanswered
The hormone that is secreted from the corpus luteum and reaches its maximum concentration on days 21 to 23 of menstruation is:
(A)
Estrogen
(B)
LH hormone
(C)
Progesterone
(D)
FSH hormone
Official Scientific Justification: The corpus luteum is formed after ovulation (day 14) by the action of LH and begins to secrete progesterone to increase the thickness of the uterine lining and its blood supply in preparation for implantation.
Question 156
Unanswered
The location where fertilization of the egg by the sperm occurs in the human female reproductive system is:
(A)
Internal uterine cavity
(B)
the vagina
(C)
Directly to the ovary
(D)
First third of the fallopian tube (near the infundibulum)
Official Scientific Justification: The fallopian tube captures the live egg, and fertilization takes place in the first third of the tube, where the egg remains fertilized for only a day or two after ovulation.
Question 157
Unanswered
The Cowper glands and the prostate gland in the male reproductive system secrete an alkaline fluid that passes into the urethra to:
(A)
Secretion of testosterone
(B)
Sperm production
(C)
Balancing the acidity of the urethra to ensure the passage and safety of sperm
(D)
Semen storage
Official Scientific Justification: Human urine is acidic and kills sperm; The alkaline fluid of Cowper's glands and prostate cleanses and neutralizes the urethra prior to the ejaculation of semen.
Question 158
Unanswered
The enzyme found in the apical body (Acrosome) of the sperm that helps it penetrate the compact envelope of the egg is:
(A)
Hyaluronidase enzyme
(B)
Amylase enzyme
(C)
Cholinesterase enzyme
(D)
pepsin enzyme
Official Scientific Justification: The egg envelope is held together by hyaluronic acid, and the apical body secretes the enzyme hyaluronase to dissolve part of the envelope to enable the animal's head to enter.
Question 159
Unanswered
Identical (monozygotic) twins arise genetically as a result of:
(A)
Fertilization of two eggs by two different sperm
(B)
Artificial parthenogenesis
(C)
Fertilization of one egg by one sperm, then the resulting cell mass is divided into two parts that are identical in genetic makeup and sex.
(D)
Fertilization of one egg by two sperm
Official Scientific Justification: Identical twins arise from one zygote and one egg, and they have the same placenta and exactly the same genetic material, sex, and blood type.
Question 160
Unanswered
The umbilical cord in the human fetus contains blood vessels that are characterized by:
(A)
One artery and two veins
(B)
Devoid of blood vessels
(C)
All its vessels carry oxygenated blood
(D)
Two arteries transport deoxygenated blood and waste from the fetus to the placenta, and one vein transports oxygenated blood and nutrients from the placenta to the fetus.
Official Scientific Justification: The umbilical cord circulation is like the pulmonary circulation: the umbilical arteries carry fetal blood exhausting the placenta, and the umbilical vein returns blood rich in oxygen and nutrients.
Question 161
Unanswered
The contraceptive method that prevents the fertilized egg from settling in the uterine lining without hindering the ovulation or fertilization processes is:
(A)
Surgical ligation of the fallopian tubes
(B)
IUD
(C)
Contraceptive pills
(D)
Condom
Official Scientific Justification: The IUD is placed in the uterus and prevents the implantation of the thymus into the lining of the uterus, while ovulation and fertilization in the fallopian tube occur naturally.
Question 162
Unanswered
Sertoli cells in the seminiferous tubules of the human male testicle play a functional role in:
(A)
Secretion of testosterone
(B)
Meiosis to produce precursors
(C)
Excretion of fructose
(D)
The secretion of a fluid that nourishes sperm inside the testicle and is thought to have an immunological function
Official Scientific Justification: Sertoli cells are somatic cells in the testicle that secrete a fluid that nourishes sperm during their maturation and are considered an immune barrier that protects male gametes.
Question 163
Unanswered
Fructose, which is found in semen to nourish sperm outside the testicle, is secreted by:
(A)
Tomorrow Cooper
(B)
Epididymis
(C)
The seminal vesicles
(D)
Prostate gland
Official Scientific Justification: The seminal vesicles secrete a fluid rich in fructose. Because fructose penetrates into the sperm cells and is burned without the need for the hormone insulin.
Question 164
Unanswered
In the life cycle of the Plasmodium malaria parasite, the human infective phase is:
(A)
Sporozoites
(B)
Merozoites
(C)
Gametophytes
(D)
Kinetic phase (okinete)
Official Scientific Justification: The female Anopheles mosquito injects its saliva containing tiny fusiform sporozoites into human blood, which immediately heads to the liver cells to begin asexual reproduction.
Question 165
Unanswered
The infective stage of the female Anopheles mosquito in the life cycle of Plasmodium malaria is:
(A)
Merozoites
(B)
Zygote
(C)
Gametocytes
(D)
Sporozoites
Official Scientific Justification: When a mosquito bites a person infected with malaria, it sucks his blood containing the gametophytes to fuse and transform into zygotes inside the mosquito's stomach.
Question 166
Unanswered
Cultivation of plant tissues in a semi-natural nutrient medium (such as coconut milk) is scientific proof of:
(A)
Effect of thyroxine
(B)
The necessity of double fertilization
(C)
A complete living plant cell contains all the genetic information necessary to form a new complete plant
(D)
Seeds are asexual
Official Scientific Justification: Steward's experiments on carrot plants demonstrated that any living somatic cell containing a nucleus and complete genetic material is capable of differentiating into a complete plant in a nutrient medium.Imam.
Question 167
Unanswered
In the human female, the second (delayed/conditional) meiotic division of the secondary oocyte takes place in:
(A)
Graaf's vesicle
(B)
Uterine cavity
(C)
Ovaries before ovulation
(D)
The fallopian tube when the sperm enters the head for fertilization to occur
Official Scientific Justification: The secondary oocyte stops at the metaphase of the second meiotic division and does not complete it to give a mature egg and a second polar body until the moment of actual fertilization.for me.
Question 168
Unanswered
The decomposition of the corpus luteum in the ovary of a non-pregnant woman at the end of the menstrual cycle results in:
(A)
Continued growth of the uterine lining
(B)
Secretion of huge amounts of LH
(C)
A sharp drop in the concentration of the hormone progesterone leads to the breakdown of the uterine lining, the rupture of its capillaries, and the occurrence of menstruation
(D)
Placenta formation
Official Scientific Justification: If the egg is not fertilized, the corpus luteum atrophies on day 28, progesterone decreases, the uterine lining disintegrates, and the vessels rupture, causing menstrual bleeding.
Question 169
Unanswered
The fetal membrane that directly surrounds the fetus and secretes a fluid that protects it from shock and dehydration and facilitates its movement is:
(A)
Amnion
(B)
Amniotic membrane (Chorion)
(C)
Plasma membrane
(D)
Vitelline membrane
Official Scientific Justification: The flaccid membrane directly surrounds the fetus and secretes amniotic fluid, which absorbs shock and protects against dehydration.
Question 170
Unanswered
The outer embryonic membrane that surrounds the uterine membrane and from which digital villi emerge, which are immersed in the uterine lining to form the placenta, is:
(A)
Amniotic membrane (Chorion)
(B)
Corpus luteum
(C)
umbilical cord
(D)
Sagging membrane
Official Scientific Justification: The chorion membrane surrounds the fetus from the outside and touches the wall of the uterus, from which the placental protrusions protrude for the exchange of nutrients and gases between the mother’s blood and the fetus.
Question 171
Unanswered
Asexual reproduction differs from sexual reproduction in that:
(A)
It is based on a single parental individual and maintains genetic stability over generations because it is based on mitosis
(B)
Provides great genetic diversity
(C)
It always requires the formation of gametes
(D)
Expensive in energy and time
Official Scientific Justification: Asexual reproduction is rapid and biologically inexpensive and produces offspring that are completely identical to the parental individual as a result of mitosis, but lacks the genetic diversity to keep up Environmental changes.
Question 172
Unanswered
Artificial parthenogenesis in flowering plants (such as the production of seedless oranges or watermelons) is carried out by:
(A)
Spraying flower stigmas with pollen extract or indole acetic acid to stimulate the ovary to form fruit without fertilization
(B)
Tissue culture
(C)
Pen vaccination
(D)
Irradiating seeds with X-rays
Official Scientific Justification: Parthenogenetic fruiting stimulates ovary hormones to become lubricated by food and form a seedless fruit. Because seeds do not form unless double fertilization of the ovules occurs.
Question 173
Unanswered
Hydra and planaria share the ability to reproduce asexually by:
(A)
Budding only
(B)
Bacteria formation
(C)
Longitudinal binary fission
(D)
Regeneration
Official Scientific Justification: The planaria worm regenerates if it is cut transversely or longitudinally, and the hydra regenerates if it is cut into several transverse parts, and each part grows into a new complete individual.
Question 174
Unanswered
Interstitial cells in the human male testicle respond directly and secrete testosterone under the influence of a pituitary hormone:
(A)
FSH hormone
(B)
Luteinizing hormone (LH)
(C)
Growth hormone
(D)
Prolactin hormone
Official Scientific Justification: In the male, LH stimulates the growth and differentiation of testicular interstitial cells and the secretion of male androgenic hormones.
Question 175
Unanswered
Combined contraceptive pills are considered an effective method because they:
(A)
The fallopian tubes close mechanically
(B)
Placental abruption
(C)
It kills sperm
(D)
It contains synthetic hormones similar to estrogen and progesterone that inhibit the secretion of FSH and LH from the pituitary, thus preventing the maturation of eggs and the occurrence of ovulation.
Official Scientific Justification: High levels of estrogen and progesterone in the blood exert negative feedback on the pituitary gland, causing the secretion of FSH and LH to stop, and ovulation is completely disrupted.
Question 176
Unanswered
The maximum number of pollen grains that can be produced from the anther of a flower containing 4 sacs, each sac with 20 germinal cells (2N) is:
(A)
640 grain
(B)
320 Pollen pill
(C)
160 grain
(D)
80 grain
Official Scientific Justification: Total maternal cells = 4 bags × 20 = 80 cell. Each maternal cell divides meiotically to give 4 small spores that turn into 4 pollen grains: 80 × 4 = 320 Pollen pill.
Question 177
Unanswered
The motile phase (motile zygote / ookinete) in the life cycle of Plasmodium malaria is characterized by:
(A)
It is diploid (2N) and penetrates the mosquito's stomach wall and turns into an egg sac
(B)
It attacks red blood cells
(C)
It secretes malaria toxin
(D)
Haploid group N
Official Scientific Justification: The ookinete is a motile worm stage (2N) that arises from zygote transformation and penetrates the lining of the mosquito’s stomach and then divides meiotically to give the egg sac (oocyst) that is haploid (N).
Question 178
Unanswered
The number of polar bodies resulting from the maturation and fertilization of 3 primary oocytes in the ovary of a human female is equal to:
(A)
6 Polar bodies
(B)
3 Polar bodies
(C)
9 Polar bodies (assuming division of the first polar body)
(D)
12 A polar body
Official Scientific Justification: Each primary oocyte gives rise to a secondary oocyte and a polar body. Upon fertilization, the secondary body divides to give an egg and a polar body, and the primary body divides into two polar bodies: 3 × 3 = 9 Polar bodies.
Question 179
Unanswered
The decisive experiment for Hershey and Chase (Hershey & Chase) To prove that DNA is the genetic material of bacteriophages, I relied on:
(A)
Use of deoxyribonuclease enzyme to analyze protein
(B)
Isolation of bacterial plasmids
(C)
Radioactive nitrogen and carbon numbering
(D)
Radioactive phosphorus numbering P-32 in DNA and radioactive sulfur numbering S-35 in the protein envelope
Official Scientific Justification: DNA It contains phosphorus but does not contain sulfur, while protein contains sulfur but does not contain phosphorus. The experiment proved that radioactive phosphorus P-32 only entered the bacteriaHis reincarnation.
Question 180
Unanswered
The enzyme used in the crucial experiment to verify the experiments of Avery and his colleagues, which completely analyzes DNA and does not affect protein or RNA, is:
(A)
Ribonuclease enzyme
(B)
DNA polymerase enzyme
(C)
Deoxyribonuclease enzyme
(D)
pepsin enzyme
Official Scientific Justification: Deoxyribonuclease specifically breaks bonds in DNA without harming proteins or RNA, and when the transformed material is treated with it, bacterial transformation stops completely.
Question 181
Unanswered
According to Chargaff's rules's Rules) In the DNA double helix, the equal ratio is always:
(A)
A = G And T = C
(B)
A + T = G + C always
(C)
A / T = 2
(D)
The ratio of adenine A equals thymine T, and the ratio of guanine G equals cytosine C (A+G). = T+C)
Official Scientific Justification: In the double helix, each adenine is linked to a thymine by two hydrogen bonds, and each guanine is linked to a cytosine by three bonds. So the sum of the purine bases = Total pyrimidines.
Question 182
Unanswered
The enzyme responsible for separating the two strands of DNA from each other by breaking hydrogen bonds during replication is:
(A)
DNA polymerase
(B)
Palace enzyme
(C)
Helicase enzyme
(D)
Ligase
Official Scientific Justification: The helix enzyme moves along the DNA molecule and breaks hydrogen bonds between complementary nitrogenous bases to separate the two strands to form a replication fork.
Question 183
Unanswered
DNA polymerase always adds new nucleotides in a specific direction:
(A)
From party 5' To party 3' For new growing bar only
(B)
From party 3' to 5' only
(C)
In both directions together
(D)
randomly
Official Scientific Justification: DNA polymerase only works in 5′ direction' to 3'; So the leading strand is built connected, while the lagging strand is built in disconnected pieces (Okazaki pieces).
Question 184
Unanswered
Okazaki Fragments formed on the die strip (5' to 3') During DNA replication they are joined by an enzyme:
(A)
Polymerase enzyme
(B)
Tac polymerase enzyme
(C)
DNA ligase
(D)
Helix enzyme
Official Scientific Justification: The ligation enzyme forms covalent phosphodiester bonds between the resulting fragments to bind them into a single continuous strand.
Question 185
Unanswered
Histone proteins responsible for shortening the length of the DNA molecule ten times and forming nucleosomes are characterized by being rich in the two basic amino acids:
(A)
Glycine and alanine
(B)
Methionine and tryptophan
(C)
Arginine and lysine (Arginine & Lysine)
(D)
Glutamic acid and aspartic acid
Official Scientific Justification: Arginine and lysine carry positive charges on the alkyl groups at the pH of the cell, so they bind strongly to the negatively charged phosphate groups in the structure DNA.
Question 186
Unanswered
If a sample of a DNA double helix contains 30% Cytosine (C), the percentage of adenine (A) bases in this sample is equal to:
(A)
20%
(B)
40%
(C)
70%
(D)
30%
Official Scientific Justification: Since C = 30%, the G = 30%And their sum = 60%. Remaining for (A + T) = 40%And since A = T, the ratio of A = 40% ÷ 2 = 20%.
Question 187
Unanswered
The number of hydrogen bonds between the nitrogenous base pair guanine and cytosine (G - C) is:
(A)
4 Links
(B)
3 Hydrogen bonds
(C)
Two hydrogen bonds
(D)
One bond
Official Scientific Justification: Guanine is linked to cytosine by three hydrogen bonds (G ≡ C)While adenine is linked to thymine by two hydrogen bonds (A = T).
Question 188
Unanswered
A synthetic chromosome mutation that occurs when a piece of chromosome separates, wraps around itself at an angle of 180 degrees, and then rejoins in the same position is called:
(A)
Deletion mutation
(B)
Transmission mutation
(C)
Repetition mutation
(D)
Inversion mutation
Official Scientific Justification: An inversion mutation occurs when a chromosome segment turns 180° They are rejoined upside down, and the order of the genes on the same chromosome changes.
Question 189
Unanswered
The sequence is repeated more than one hundred thousand times in the middle of one of the chromosomes of the Drosophila insect (fruit fly) and does not code for any protein:
(A)
AGACT
(B)
AUG
(C)
UAA
(D)
TATAAT
Official Scientific Justification: In Drosophila, the AGACT sequence is repeated hundreds of thousands of times in the middle of the chromosome and does not code for building any proteins.
Question 190
Unanswered
Telomeres are found at the ends of eukaryotic chromosomes and perform an important function in:
(A)
Protecting chromosomes from corrosion and merging with each other and maintaining their structure
(B)
Construction of ribosomes
(C)
Synthesis of enzymes
(D)
Centromere doubling
Official Scientific Justification: Telomeres are non-coding sequences at the ends of chromosomes that protect important genetic material from loss during repeated replication cycles.
Question 191
Unanswered
A segment of a DNA double helix consisting of 600 nucleotides. The number of complete turns in this segment is equal to:
(A)
15 roll
(B)
10 Rolls
(C)
30 Full roll
(D)
60 roll
Official Scientific Justification: One turn of the double helix contains 20 nucleotides (10 nucleotides on each strand). So the number of turns = 600 ÷ 20 = 30 roll.
Question 192
Unanswered
DNA Repair Enzymes, which number approximately 20 enzymes, depend for their work on:
(A)
The presence of a corresponding healthy template strip complementary to the damaged strip to guide its sequence in repair
(B)
Production of lipoproteins
(C)
Heat irradiation of the cell
(D)
Destruction of the infected cell
Official Scientific Justification: Double screw construction provides two complementary versions; If a base on a strand is damaged, the repair enzyme guides the correct corresponding strand to restore the correct base.
Question 193
Unanswered
Which of the following organisms has its genetic material as a single molecule of RNA rather than DNA?
(A)
Escherichia coli bacteria
(B)
Bacteriophage T2
(C)
Human immunodeficiency virus (HIV), polio virus, influenza and coronavirus
(D)
Yeast
Official Scientific Justification: Some viruses are genetically based on RNA and have a very high mutation rate because there is no corresponding strand to repair damage.
Question 194
Unanswered
In Griffith's bacterial transformation experiment, mice died when they were injected with:
(A)
Live R bacteria alone
(B)
Sterile saline solution
(C)
Heat-killed S bacteria alone
(D)
A mixture of heat-killed S bacteria with live R bacteria
Official Scientific Justification: The genetic material from the dead S strain was transferred to the live R strain, which turned into S, causing severe pneumonia and the death of the mice, which is known as bacterial transformation.
Question 195
Unanswered
The atom in the pentose sugar molecule (dioxyribose) to which the nitrogenous base is linked by a covalent bond is:
(A)
Carbon atom number 2'
(B)
Carbon atom number 5'
(C)
Carbon atom number 1' (C1')
(D)
Carbon atom number 3'
Official Scientific Justification: The nitrogenous base is attached to carbon 1' Sugar has a covalent bond, and the phosphate group is attached to carbon atom 5'.
Question 196
Unanswered
Party 3' For a DNA strand that ends with a group:
(A)
Free amine (-NH2)
(B)
Free carboxylate (-COOH)
(C)
Free phosphate (-PO4)
(D)
Free hydroxyl (-OH)
Official Scientific Justification: The DNA strand has a polarity: the 5′ end' It carries a free phosphate linked to C5'And party 3' It carries a free hydroxyl linked to C3'.
Question 197
Unanswered
In prokaryotic cells (such as bacteria), a single circular DNA molecule attaches to the plasma membrane at:
(A)
One or more sites from which DNA replication begins
(B)
Nuclear envelope
(C)
Centrosome
(D)
Ribosome
Official Scientific Justification: Prokaryotes lack a nuclear membrane and have bare circular DNA attached to the plasma membrane at the site of replication initiation.
Question 198
Unanswered
Common and economically beneficial chromosome duplication in the plant kingdom (such as strawberries, wheat, and apples) leads to:
(A)
Plant sterility and death
(B)
Larger cells and tissues and larger, sweeter and more productive fruits
(C)
Root loss
(D)
Loss of chlorophyll
Official Scientific Justification: Polyploidy in plants doubles their genes, which leads to increased production of enzymes and an increase in the size of cells and organs such as flowers and fruits.
Question 199
Unanswered
A chemical substance used in the laboratory to cause mutations and chromosome duplication in the growing tips of plants is:
(A)
Hyaluronic acid
(B)
Glycerin
(C)
Sucrose solution
(D)
Colchicine, mustard gas, or nitrous acid
Official Scientific Justification: Colchicine prevents the formation of spindle fibers during cell division, so the duplicated chromosomes remain within one cell, generating polyploid cells.
Question 200
Unanswered
Mutations that are inherited to future generations and occur in reproductive cells that produce gametes are called:
(A)
Temporary spikes
(B)
Gamete mutations
(C)
Somatic mutations
(D)
Rebound mutations
Official Scientific Justification: Gamete mutations occur in the gonad follicles and are transmitted through the sperm or eggs of the offspring and appear in all their cells.
Question 201
Unanswered
The Ancon breed mutation in sheep with short, arched legs is considered a mutation:
(A)
Harmful innovation
(B)
Numerical chromosome
(C)
Fatal to fetuses
(D)
A useful mechanism that the breeder kept in mind to prevent sheep from jumping fences and damaging crops
Official Scientific Justification: The Ancon mutation appeared spontaneously on a farm, and the breeder was pleased with it and worked to multiply it because short-legged sheep were no longer able to climb barriers.
Question 202
Unanswered
The percentage of DNA encoding the construction of proteins and enzymes in the genetic content of eukaryotic cells (such as humans) represents approximately:
(A)
50%
(B)
100%
(C)
Less than 2% Of the total cell genome
(D)
More than 90%
Official Scientific Justification: The Human Genome Project has demonstrated that there are only 1.5 genes encoding functional proteins% to 2% Of the human genome, the remainder are regulatory and non-coding sequences.
Question 203
Unanswered
Connecting two complementary DNA strands by hydrogen bonds makes them:
(A)
Two parallel strands in opposite directions that are chemically complementary
(B)
Two exactly identical bars in the same direction
(C)
connected by peptide bonds
(D)
criss-crossing each lap
Official Scientific Justification: The two strands are not identical, but complementary and opposite; Where adenine corresponds to thymine, guanine corresponds to cytosine, and terminal 5' Corresponds to party 3'.
Question 204
Unanswered
The amount of DNA in a human female secondary oocyte compared to a resting somatic skin cell (before replication begins) is:
(A)
Equal (contains 46 DNA molecules in the form of 23 diploid chromosomes)
(B)
Quarter
(C)
Weakness
(D)
Half the quantity
Official Scientific Justification: The secondary oocyte is the result of meiosis I and contains 23 chromosomes, each of which is composed of 2 chromatids (i.e. 46 DNA molecules), which is the same number of DNA molecules in a body cell.Very important.
Question 205
Unanswered
The standard start codon in an mRNA molecule recognized by the first tRNA molecule carrying methionine is:
(A)
UAG
(B)
UAA
(C)
AUG
(D)
UGA
Official Scientific Justification: AUG It is the start codon in all mRNA molecules and encodes for methionine and begins the synthesis of the polypeptide chain.
Question 206
Unanswered
Stop codons that bind to the release factor to terminate the translation process are:
(A)
AUG And GUG and UUG
(B)
AAA And UUU and GGG
(C)
CCC And GGG and TTT
(D)
UAA And UAG and UGA
Official Scientific Justification: The three stop codons (UAA, UAG, UGA) It does not bind to any tRNA molecule, but rather to a release factor protein to disassemble the ribosome and terminate translation.
Question 207
Unanswered
The anticodon on the tRNA molecule carrying methionine is:
(A)
AUG
(B)
GUA
(C)
UAC
(D)
CAU
Official Scientific Justification: The start codon is 5'-AUG-3'The anticodon of its complementary codon on the corresponding tRNA loop is 3'-UAC-5'.
Question 208
Unanswered
The enzyme responsible for constructing an mRNA strand from one of the two DNA strands (template strand 3' to 5') he:
(A)
Binding enzyme
(B)
DNA polymerase enzyme
(C)
RNA polymerase
(D)
Palace enzyme
Official Scientific Justification: RNA polymerase enzyme uncoils the double helix locally and transcribes the mRNA strand integrated with the DNA template strand 5' down' to 3'.
Question 209
Unanswered
The polyadenyne tail (Poly-A Tail) added to the end of the mRNA molecule in eukaryotes consists of about 200 adenine nucleotides and functionally functions to:
(A)
Protecting the mRNA molecule from degradation by enzymes in the cytoplasm
(B)
Formation of the nuclear envelope
(C)
Binding to the polymerase enzyme
(D)
Encoding polar amino acids
Official Scientific Justification: The polyadenyne tail is a non-coding sequence added to end 3' To protect mRNA from cytoplasmic enzymes and help transport it to the ribosome.
Question 210
Unanswered
The enzyme that catalyzes the peptidyl transferase reaction and the formation of the peptide bond between amino acids during translation is:
(A)
Part of the rRNA molecule that makes up the subunit of the ribosomal subunit
(B)
Release factor protein
(C)
DNA polymerase enzyme
(D)
Helix enzyme
Official Scientific Justification: Peptidyl transferase is a catalytic activity carried out by a segment of rRNA in the ribosomal subunit to form peptide bonds between successive acids.
Question 211
Unanswered
Bacterial restriction endonucleases recognize specific nucleotide sequences called recognition sites, and are characterized by:
(A)
Stop codons only
(B)
Lipoprotein molecules
(C)
Palindromes of 4 to 8 pairs read in the same order on both strands in 5′ direction.' to 3'
(D)
Asymmetric repetitive sequences
Official Scientific Justification: Recognition sites for shortening enzymes Palindromic sequences such as GAATTC reads are identical on the two strands of 5′' to 3' It leaves individual sticky ends.
Question 212
Unanswered
The enzyme extracted from RNA viruses and used to convert mRNA into a single strand of complementary DNA (cDNA) is:
(A)
RNA polymerase enzyme
(B)
Ligase enzyme
(C)
Palace enzyme
(D)
Reverse transcriptase
Official Scientific Justification: Reverse transcriptase enzyme makes a DNA strand complementary to an RNA molecule, and is used in genetic engineering to isolate human genes without introns.
Question 213
Unanswered
The thermal multiplex device (PCR - Polymerase Chain Reaction) depends on an enzyme that tolerates high temperatures called:
(A)
Human DNA polymerase enzyme
(B)
Taq polymerase enzyme
(C)
RNA polymerase enzyme
(D)
Amylase enzyme
Official Scientific Justification: TAC polymerase is extracted from hot spring bacteria and can withstand temperatures of 95 degrees Celsius°C To multiply millions of copies of a specific DNA sequence in just minutes.
Question 214
Unanswered
DNA hybridization depends on the ability of single strands from different sources to combine if:
(A)
They are just the same height and weight
(B)
Treatment with shortening enzyme
(C)
Made in the same cell
(D)
They contain complementary sequences of nitrogenous bases and are linked by hydrogen bonds
Official Scientific Justification: When DNA is heated to 100°C The two strands separate, and upon gradual cooling any single strands containing degrees of complementarity attract each other and the intensity of adhesion indicates evolutionary relatedness.
Question 215
Unanswered
The number of codons that code for the 20 amino acids in the genetic table is equal to:
(A)
64 Codona
(B)
61 Codons (out of a total of 64 codons after excluding the three stop codons)
(C)
32 Codona
(D)
20 Codona
Official Scientific Justification: The triple blade produces 4³ = 64 codon; Three of them are stop codons that do not code for acids, leaving 61 codons for different amino acids.
Question 216
Unanswered
The genetic code is characterized as universal because:
(A)
It is found in the nucleus only
(B)
It does not change with mutations
(C)
The same codons code for the same amino acids in all organisms from bacteria to humans, confirming the common origin of life
(D)
It consists of only two letters
Official Scientific Justification: The fact that a codon such as UUU encodes for phenylalanine in all forms of life is definitive evidence of the unity of the genetic origin of living organisms.
Question 217
Unanswered
Modifying enzymes produced by bacteria work to:
(A)
Adding methyl groups (-CH3) to the nucleotides of recognition sites in bacterial DNA to protect it from their shortening enzymes.
(B)
Cell wall construction
(C)
Cracking viruses
(D)
Sugar analysis
Official Scientific Justification: Bacteria produce modification enzymes that add methylation to recognition points in their own genome so they are not digested by the shortening enzymes they made to kill invading viruses.
Question 218
Unanswered
The first human protein produced commercially using recombinant DNA technology to treat diabetics is:
(A)
Growth hormone
(B)
Interferon protein
(C)
Hemoglobin
(D)
Human hormone insulin (Insulin)
Official Scientific Justification: In 1982, the human insulin gene was inserted into the plasmids of Escherichia coli bacteria to produce abundant, pure, pathogen-free human insulin.For allergies.
Question 219
Unanswered
The number of amino acid molecules in a polypeptide chain resulting from mRNA translation consisting of 303 nucleotides, including the start and stop codons, is equal to:
(A)
101 Acid
(B)
99 Acid
(C)
300 Acid
(D)
100 Amino acid
Official Scientific Justification: Number of codons = 303 ÷ 3 = 101 Codon. The final stop codon does not code for an amino acid, so the number of acids in the chain = 101 - 1 = 100 Amino acid.
Question 220
Unanswered
The two main functional sites on the tRNA molecule are:
(A)
Start location and stop location
(B)
Phosphate site and sugar site
(C)
The amino acid binding site is at the 3′ end' (sequence CCA), and anticodon site
(D)
DNA polymerase site and binding site
Official Scientific Justification: tRNA Holds tip 3' The CCA sequence binds to the amino acid, and at the opposite end is the anticodon loop to bind to the appropriate mRNA codon within the ribosome.
Question 221
Unanswered
In gene cloning technology, a ligase is used to:
(A)
Linking the integrated sticky ends of a target gene to the sticky ends of a circular plasmid
(B)
Breaking down proteins
(C)
Cut the plasmid
(D)
mRNA transcription
Official Scientific Justification: After cutting the target gene and the plasmid with the same cutting enzyme, integrated sticky ends are formed, and the splicing enzyme forms phosphodiester bonds to fuse them together.
Question 222
Unanswered
Polyribosome is a vital cellular structure consisting of:
(A)
A large number of ribosomes (up to 100 ribosomes) attach to a single mRNA molecule to translate it simultaneously and quickly build many copies of the protein.
(B)
Accumulated peripheral granules
(C)
Fusion of two nuclei
(D)
Mitochondrial aggregation
Official Scientific Justification: Polysomes accelerate protein synthesis; Each ribosome moves along the mRNA strand and sequentially builds its own version of the polypeptide.
Question 223
Unanswered
In eukaryotic cells, rRNA molecules are synthesized and assembled under ribosomal subunits within:
(A)
Nucleolus
(B)
Golgi apparatus
(C)
directly into the cytoplasm
(D)
Smooth endoplasmic reticulum
Official Scientific Justification: The nucleolus within the cell nucleus is the factory of ribosomes; Where 4 types of rRNA combine with 70 types of polypeptide proteins to form ribosomal units.
Question 224
Unanswered
Sticky Ends resulting from the action of shortening enzymes are characterized by:
(A)
Short, extended single strands of unpaired nucleotides capable of spontaneous association with complementary ends
(B)
Collagen thickened ends
(C)
Inactive phosphate sequences
(D)
Ends surrounded by peptide bonds
Official Scientific Justification: The diagonal cut of the shortening enzyme leaves single sticky ends that easily join with any other DNA fragment treated with the same enzyme to form hybrid DNA.
Question 225
Unanswered
Experiments using genes for resistance to insect pests in crop plants (such as the Bacillus thuringiensis gene) are an application to:
(A)
Parthenogenetic fruiting
(B)
Genetic engineering and development of genetically modified plants resistant to pests without chemical pesticides
(C)
Artificial parthenogenesis
(D)
Propagation by hydroponics
Official Scientific Justification: Transferring the bacterial toxin gene to plants protects them from cotton worms and pests. The larvae feed on the leaves and die from the self-produced bacterial toxin.
Question 226
Unanswered
The two sites on the subunit of the ribosomal subunit where the two tRNA molecules stabilize during polypeptide chain elongation are:
(A)
The location of the palace and the location of the IUD
(B)
Coiling site and binding site
(C)
Location 5' And site 3'
(D)
Peptidyl site (P) and aminoacyl site (A)
Official Scientific Justification: The P site holds the growing polypeptide chain and the A site receives the new tRNA carrying the next amino acid to complete the peptidyl transfer reaction.
Question 227
Unanswered
The global scientific project that was able to decipher and arrange more than 3 billion pairs of nitrogenous bases in human cells is:
(A)
Virus study project
(B)
Stem cell project
(C)
Human Genome Project
(D)
Acquired immunity project
Official Scientific Justification: The human genome has completed the complete mapping of human DNA sequences and identified the loci of genes associated with hereditary diseases and biological traits.