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Biology & Geology

Chapter 1 - Support and Movement in Living Organisms

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Chapter 2 - Hormonal Coordination in Living Organisms

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Chapter 3 - Reproduction in Living Organisms

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Chapter 4 - Immunity in Living Organisms

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Chapter 5 - Molecular Biology - DNA Structure and Function

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Chapter 6 - Molecular Biology - RNA, Protein Synthesis and Genetic Engineering

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Chapter 7 - Geology, Earth Sciences and Ecology

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Quiz

Lesson 2 Quiz: Movement in Plants and Muscle Contraction Mechanics in Humans

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  • Questions count: 20
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1.
Which sarcomere component maintains a constant length during both full contraction and relaxation?
The A-band
The entire sarcomere
The H-zone
The I-band
2.
Which of the following first-row transition metal ions exhibits the highest theoretical magnetic moment in its ground state?
Cu2+ ([Ar] 3d9 with 1 unpaired electron)
Zn2+ ([Ar] 3d10 with 0 unpaired electrons)
Cr3+ ([Ar] 3d3 with 3 unpaired electrons)
Fe3+ ([Ar] 3d5 with 5 unpaired electrons)
3.
The electronic configurations of both Chromium (24Cr) and Copper (29Cu) are anomalous due to the enhanced stability associated with:
Pairing of all electrons in the outer valence level
High electronegativity differences
Half-filled (3d5) and completely filled (3d10) d-subshells respectively
Completely empty 4s subshells
4.
The atomic radii of the elements from Chromium to Copper remain remarkably steady and nearly constant across the first transition series because of:
The identical number of neutrons in their nuclei
Decreasing ionization energies
The sudden increase in atomic mass
The mutual compensation between the increasing nuclear charge and the repulsive forces among accumulated 3d electrons
5.
Boyle's Law states that for a fixed mass of an ideal gas kept at constant temperature, the volume V is:
Independent of pressure changes
Inversely proportional to its absolute pressure P (P1 * V1 = P2 * V2)
Directly proportional to pressure
Directly proportional to absolute temperature
6.
Which of the following compounds exhibits polar covalent bonding due to a significant difference in electronegativity between 0.4 and 1.7?
Water (H2O)
Chlorine gas (Cl2)
Methane (CH4)
Sodium chloride (NaCl)
7.
Solid ionic compounds such as crystal NaCl do NOT conduct electricity in the solid state because:
Electrons are moving too rapidly
They decompose in the presence of air
They contain no electrical charges
Their ions are tightly locked in fixed positions within the rigid crystal lattice and cannot move freely
8.
A metallic bond is physically described as the electrostatic attraction between:
Dipole molecules in a polar liquid
Positive metal cations in the crystal lattice and the mobile sea of delocalized valence electrons
Protons and neutrons in the nucleus
Positive ions and negative non-metal anions
9.
Phenolphthalein indicator cannot distinguish between an acidic solution and a neutral solution because:
It precipitates in both
It is red in both
It is colorless in both
It is blue in both
10.
According to the 2026/2027 Egyptian STEM biology syllabus, what is the exact scientific deduction regarding: Sliding Filament Theory of Muscle Contraction (Huxley)?
Z-lines move away from each other as the muscle contracts
Cross-bridges pull actin filaments outward away from the M-line
During sarcomere contraction, actin filaments slide over myosin filaments; the I-band and H-zone shorten, while the A-band length remains strictly constant
Both A-band and myosin filaments shrink by 50% in length
11.
Painful and sudden muscle tension often occurs as a result of a severe deficiency in:
Carbon dioxide gas
Vitamin C
ATP molecules needed to separate cross-links from actin filaments
Lactic acid
12.
According to Huxley's sliding filament theory, when a muscle fiber contracts completely:
Z lines diverge
The semiluminal area (H) is absent or disappears, the length of the muscle segment is shortened, and the Z lines converge
The length of the illuminated area (I) increases
The length of the myosin filaments doubles
13.
Cross-links that extend from myosin filaments and act as hooks to pull actin are formed with the help of ions:
Zinc ions
Calcium ions Ca2+
Iron ions Fe2+
Iodine ions
14.
Which of the following substances are consumed during both muscle contraction and relaxation?
Cholinesterase enzyme
ATP molecules (adenosine triphosphate)
Glycogen only
Acetic acid
15.
Which of the following muscle proteins is considered a structural protein with constant length during mechanical contraction and relaxation?
Lactic acid
Hemoglobin
Myoglobin
Myosin and actin (their positions change by overlapping, but the length of the filaments does not change)
16.
Complements are a group of plasma proteins that activate when an antibody binds to an antigen and work to:
Decomposing the antigenic envelope and dissolving its contents to facilitate their ingestion by macrophages
Activate viruses
Blood clotting
Histamine secretion
17.
Monocytes are functionally capable of leaving the bloodstream when needed:
Transform into active macrophages to engulf microbes and cellular debris
Histamine secretion
Antibody formation
Transformation into B cells
18.
The enzyme found in the apical body (Acrosome) of the sperm that helps it penetrate the compact envelope of the egg is:
Hyaluronidase enzyme
pepsin enzyme
Cholinesterase enzyme
Amylase enzyme
19.
The Ancon breed mutation in sheep with short, arched legs is considered a mutation:
Harmful innovation
Numerical chromosome
Fatal to fetuses
A useful mechanism that the breeder kept in mind to prevent sheep from jumping fences and damaging crops
20.
The first human protein produced commercially using recombinant DNA technology to treat diabetics is:
Human hormone insulin (Insulin)
Interferon protein
Growth hormone
Hemoglobin
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