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Course: Alhussan Biology — Stage 7
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Alhussan Biology — Stage 7

Chapter 1: Classification and Life

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Chapter 2: Cells and Organisation

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Chapter 3: Microorganisms and Decomposers

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Chapter 4: The Physical Environment and Water Cycle

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Quiz

3.6 Investigating rotting rates — Quiz

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  • Questions count: 50
  • Passing grade: B+
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1.
Mould cover on bread in different places after a week. Which graph shows these results correctly?
Dr Dabour Hub Academy - figure 1
A
B
C
D
2.
Which term matches this definition? “A testable idea based on scientific knowledge.”
Antiseptic
Hypothesis
Rate of decay
Coccus
3.
The graph shows rate of decay against temperature. Why does the rate fall above 40 °C?
Dr Dabour Hub Academy - figure 2
Enzymes of the decomposers are damaged and microorganisms die
The decomposers are frozen
Decay always rises with temperature
There is too much oxygen
4.
Mass lost by potato samples in one week. At what value of "Temperature (°C)" is "Mass lost (g)" smallest?
Dr Dabour Hub Academy - figure 3
20
30
5
10
5.
A potato of 40 g was 41 g after a week. What percentage of its mass was lost?
−1%
102%
−25%
−2%
6.
Which term matches this definition? “The variable you measure.”
Lactic acid
Dependent variable
Fermentation
Control variable
7.
Which is the correct definition of “pH”?
Substances plants absorb from soil to build cells.
A single-celled fungus used in baking and brewing.
A model showing one feeding pathway.
A measure of how acidic or alkaline a solution is.
8.
Which term matches this definition? “A fungus that grows on food.”
Toxin
Mould
Penicillin
Enzyme
9.
Which statement is correct?
One sample at each temperature is enough.
A word description is the best measure.
Some mould spores cause allergies.
The type of food can change between samples.
10.
Milk pH fell from 6.7 to 4.6 in 5 days. What was the mean fall per day?
2.10
0.42
2.26
1.34
11.
Rate of decay at different temperatures. What is the value of "Rate of decay (units)" when "Temperature (°C)" is 40?
Dr Dabour Hub Academy - figure 4
1
17
0
6
12.
Milk pH fell from 6.6 to 4.8 in 5 days. What was the mean fall per day?
2.28
1.80
0.36
1.32
13.
Mould cover on bread in different places after a week. Which has the greatest value?
Dr Dabour Hub Academy - figure 5
Fridge
Freezer
Warm cupboard
Kitchen
14.
Mould cover on bread in different places after a week. Which graph shows these results correctly?
Dr Dabour Hub Academy - figure 6
A
B
C
D
15.
Which is the correct definition of “Control variable”?
Spread of pathogens in tiny droplets from coughs and sneezes.
A variable kept the same.
A covering over the nose and mouth that catches droplets.
Practices that keep things clean to stop disease.
16.
Milk pH fell from 6.7 to 4.6 in 4 days. What was the mean fall per day?
2.83
2.10
1.68
0.53
17.
Three samples lost 6, 5 and 6 g. What is the mean loss?
56.7 g
17.0 g
5.7 g
7.0 g
18.
Milk pH fell from 6.7 to 4.8 in 5 days. What was the mean fall per day?
1.90
2.30
1.34
0.38
19.
pH of milk left at room temperature. What is the value of "pH" when "Day" is 5?
Dr Dabour Hub Academy - figure 7
5.0
4.4
4.6
5.7
20.
Which term matches this definition? “How quickly material is broken down.”
Primary consumer
Antiseptic
Rate of decay
Herbivore
21.
Which statement is NOT correct?
Use several samples at each temperature and calculate a mean.
The potato at 30 °C lost mass faster than at 10 °C.
Mouldy bags should be opened to look closely.
Mould grew more slowly in the coolest place.
22.
Which statement is correct?
The type of food can change between samples.
One sample at each temperature is enough.
A word description is the best measure.
The hypothesis was supported because warmer samples decayed faster.
23.
Which is the correct definition of “Dependent variable”?
The variable you measure.
A single-celled organism with no nucleus.
Digestion outside the body of the organism.
Respiration without oxygen giving ethanol and carbon dioxide.
24.
pH of milk left at room temperature. Which graph shows these results correctly?
Dr Dabour Hub Academy - figure 8
A
B
C
D
25.
A potato of 40 g was 46 g after a week. What percentage of its mass was lost?
115%
−6%
−13%
−15%
26.
Three samples lost 5, 6 and 6 g. What is the mean loss?
56.7 g
5.7 g
6.5 g
17.0 g
27.
Which is the correct definition of “Prediction”?
What you expect to happen if the hypothesis is right.
A layer that protects a bacterium from drying out.
Microscopic threads of a fungus.
Digestion outside the body of the organism.
28.
pH of milk left at room temperature. Which graph shows these results correctly?
Dr Dabour Hub Academy - figure 9
A
B
C
D
29.
Which statement is correct?
One sample at each temperature is enough.
An elephant's body becomes a skeleton in weeks or months.
Mouldy bags should be opened to look closely.
Cold kills all decomposers.
30.
Which statement is NOT correct?
Change in mass is the dependent variable.
Warmer samples decayed more slowly.
As milk turns sour its pH falls.
The potato at 30 °C lost mass faster than at 10 °C.
31.
Which is the correct definition of “Percentage cover”?
A model showing one feeding pathway.
The proportion of a surface covered, as a percentage.
A skin infection spread by direct contact.
What you expect to happen if the hypothesis is right.
32.
Wash hands ____.
never
before only
with oil
afterwards
33.
Change in mass is the ____ variable.
dependent
fixed
control
independent
34.
An elephant's body becomes a skeleton in weeks or ____.
centuries
months
seconds
hours
35.
The hypothesis was that decomposition is slower at ____ temperatures.
low
high
medium
all
36.
Label and ____ each bag clearly.
shake
eat
seal
open
37.
The potato at 30 °C lost mass ____ than at 10 °C.
slower
faster
at the same rate
not at all
38.
Some mould spores cause ____.
heat
light
allergies
growth
39.
A good measure uses a ____.
number
feeling
colour
word
40.
Mould grew more slowly in the ____ place.
brightest
wettest
warmest
coolest
41.
True or false? Using several samples at each temperature and calculating a mean improves reliability.
True
False
42.
True or false? Cold only slows microorganisms.
True
False
43.
True or false? Mass loss is the independent variable.
True
False
44.
True or false? Never open bags where mould is growing.
True
False
45.
True or false? Rate of decay against temperature rises to a peak then falls sharply.
True
False
46.
True or false? As milk turns sour its pH falls.
True
False
47.
True or false? Temperature is the independent variable.
True
False
48.
True or false? Decay rate rises forever with temperature.
True
False
49.
True or false? Woolly mammoths were found preserved in ice.
True
False
50.
True or false? Cold kills all decomposers.
True
False
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Part of Chapter 3: Microorganisms and Decomposers — see every lesson and quiz in this unit.
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