,A student places identical potato cylinders into four solutions.
Solution Initial mass / g Final mass / g
A 2.40 2.76
B 2.40 2.52
C 2.40 2.39
D 2.40 2.12
Which solution was most likely closest to the concentration inside the potato cells?
A. A
B. B
C. C
D. D
Correct answer: C
Rationale:
There is almost no change in mass in solution C. This suggests there was little or no net
movement of water, meaning the water concentration outside the cells was approximately
equal to that inside the cells.
Question 2
A microscope image of a cell has a diameter of 36 mm. The actual diameter of the cell is 12
μm.
What is the magnification?
A. ×30
B. ×300
C. ×3000
D. ×30 000
Correct answer: C
Rationale:
36 mm = 36 000 μm.
Magnification = image size ÷ actual size
36 000 ÷ 12 = 3000.
The major trap is failing to convert millimetres into micrometres.
,Question 3
A student claims:
"A bacterial cell must contain a nucleus because it contains genetic material."
Which statement is correct?
A. Correct, because all cells containing DNA have nuclei.
B. Correct, because DNA can only function inside a nucleus.
C. Incorrect, because bacterial DNA is not enclosed within a nucleus.
D. Incorrect, because bacteria do not contain DNA.
Correct answer: C
Rationale:
Bacteria are prokaryotic cells. Their genetic material is not enclosed in a nucleus. Bacteria do
contain DNA.
Question 4
A cell contains many mitochondria and a large number of ribosomes.
Which combination best explains this?
A. The cell requires large amounts of energy and synthesises many proteins.
B. The cell carries out photosynthesis and stores large quantities of water.
C. The cell requires less energy but produces large quantities of glucose.
D. The cell is specialised only for transporting oxygen.
Correct answer: A
Rationale:
Mitochondria are the site of aerobic respiration, which releases energy for cellular processes.
Ribosomes are involved in protein synthesis. A cell containing many of both structures is
likely highly active.
Question 5
A tumour develops after a mutation affects a gene controlling cell division.
, Which sequence is most accurate?
A. Mutation → cell death → uncontrolled division → tumour
B. Mutation → uncontrolled cell division → accumulation of abnormal cells → tumour
C. Mutation → increased respiration → cell specialisation → tumour
D. Mutation → osmosis → cell enlargement → tumour
Correct answer: B
Rationale:
Mutations can affect genes controlling the cell cycle. If normal controls are lost, cells may
divide uncontrollably, producing an abnormal mass of cells.
Question 6
An enzyme works at 37 °C. Its rate increases when temperature rises from 20 °C to 35 °C but
decreases sharply at 50 °C.
Which explanation is best?
A. The enzyme becomes more concentrated at 50 °C.
B. The substrate disappears because enzymes are used up.
C. The enzyme's active site changes shape at high temperature.
D. The enzyme gains additional active sites at 50 °C.
Correct answer: C
Rationale:
At temperatures above the optimum, bonds maintaining the enzyme's structure can be
disrupted. The active site changes shape and becomes less complementary to the substrate.
The enzyme is denatured.
Question 7
An enzyme has an optimum pH of 7.
Which change would most directly reduce enzyme activity?
A. Increasing substrate concentration while substrate is limiting
Solution Initial mass / g Final mass / g
A 2.40 2.76
B 2.40 2.52
C 2.40 2.39
D 2.40 2.12
Which solution was most likely closest to the concentration inside the potato cells?
A. A
B. B
C. C
D. D
Correct answer: C
Rationale:
There is almost no change in mass in solution C. This suggests there was little or no net
movement of water, meaning the water concentration outside the cells was approximately
equal to that inside the cells.
Question 2
A microscope image of a cell has a diameter of 36 mm. The actual diameter of the cell is 12
μm.
What is the magnification?
A. ×30
B. ×300
C. ×3000
D. ×30 000
Correct answer: C
Rationale:
36 mm = 36 000 μm.
Magnification = image size ÷ actual size
36 000 ÷ 12 = 3000.
The major trap is failing to convert millimetres into micrometres.
,Question 3
A student claims:
"A bacterial cell must contain a nucleus because it contains genetic material."
Which statement is correct?
A. Correct, because all cells containing DNA have nuclei.
B. Correct, because DNA can only function inside a nucleus.
C. Incorrect, because bacterial DNA is not enclosed within a nucleus.
D. Incorrect, because bacteria do not contain DNA.
Correct answer: C
Rationale:
Bacteria are prokaryotic cells. Their genetic material is not enclosed in a nucleus. Bacteria do
contain DNA.
Question 4
A cell contains many mitochondria and a large number of ribosomes.
Which combination best explains this?
A. The cell requires large amounts of energy and synthesises many proteins.
B. The cell carries out photosynthesis and stores large quantities of water.
C. The cell requires less energy but produces large quantities of glucose.
D. The cell is specialised only for transporting oxygen.
Correct answer: A
Rationale:
Mitochondria are the site of aerobic respiration, which releases energy for cellular processes.
Ribosomes are involved in protein synthesis. A cell containing many of both structures is
likely highly active.
Question 5
A tumour develops after a mutation affects a gene controlling cell division.
, Which sequence is most accurate?
A. Mutation → cell death → uncontrolled division → tumour
B. Mutation → uncontrolled cell division → accumulation of abnormal cells → tumour
C. Mutation → increased respiration → cell specialisation → tumour
D. Mutation → osmosis → cell enlargement → tumour
Correct answer: B
Rationale:
Mutations can affect genes controlling the cell cycle. If normal controls are lost, cells may
divide uncontrollably, producing an abnormal mass of cells.
Question 6
An enzyme works at 37 °C. Its rate increases when temperature rises from 20 °C to 35 °C but
decreases sharply at 50 °C.
Which explanation is best?
A. The enzyme becomes more concentrated at 50 °C.
B. The substrate disappears because enzymes are used up.
C. The enzyme's active site changes shape at high temperature.
D. The enzyme gains additional active sites at 50 °C.
Correct answer: C
Rationale:
At temperatures above the optimum, bonds maintaining the enzyme's structure can be
disrupted. The active site changes shape and becomes less complementary to the substrate.
The enzyme is denatured.
Question 7
An enzyme has an optimum pH of 7.
Which change would most directly reduce enzyme activity?
A. Increasing substrate concentration while substrate is limiting
