Topic 2 Assessment Booklet
Marks = 134 Time Allowed 165 minutes
Q1.
(a) A student prepared a stained squash of cells from the tip of an onion root and
observed it using an optical microscope.
During the preparation of the slide, he:
• cut the first 5 mm from the tip of an onion root and placed it on a glass slide
• covered this tip with a drop of stain solution and a cover slip
• warmed the glass slide
• pressed down firmly on the cover slip.
He identified and counted nuclei in different stages of the cell cycle.
Explain why the student:
1. used only the first 5 mm from the tip of an onion root.
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2. pressed down firmly on the cover slip.
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(2)
Figure 1 shows the cells the student saw in one field of view. He used this field of view to
calculate the length of time these onion cells spent in anaphase of mitosis.
Figure 1
Page 1 of 45
,(b) Scientists have found the mean length of time spent by onion cells in anaphase of
mitosis is 105 minutes. They also found the cell cycle of cells in the onion root
shown in Figure 1 takes 1080 minutes.
32 whole cells are shown in Figure 1.
Use this information and Figure 1 to calculate the length of time the cells of this
onion root are in anaphase and then calculate the percentage difference between
your answer and the mean length of time found by the scientists.
Show your working.
Answer = ____________________ %
(2)
(c) Tick (✓) the name given to the division of cytoplasm during the cell cycle.
A Binary fission
B Cytokinesis
C Phagocytosis
D Segregation
Page 2 of 45
, (1)
(d) Describe and explain what the student should have done when counting cells to
make sure that the mitotic index he obtained for this root tip was accurate.
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(2)
(e) A scientist treated growing tips of onion roots with a chemical that stops roots
growing. After 24 hours, he prepared a stained squash of these root tips.
Figure 2 is a drawing showing the chromosomes in a single cell observed in the
squash of one of these root tips in anaphase. This cell was typical of other cells in
anaphase in these root tips.
Figure 2
Use all of this information to suggest how the chemical stops the growth of roots.
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Page 3 of 45
, ___________________________________________________________________
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(3)
(Total 10 marks)
Q2.
(a) What is an antigen?
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(2)
(b) What is an antibody?
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(2)
Poliomyelitis is an infection caused by a virus.
A doctor vaccinated a group of patients against poliomyelitis. He gave each patient two
doses of vaccine, 3 months apart.
An immunologist tested three samples of blood from each of the patients:
• (sample 1) taken 2 weeks before the first dose of vaccine
• (sample 2) taken 2 weeks after the first dose of vaccine
• (sample 3) taken 2 weeks after the second dose of vaccine.
He measured the concentration of antibodies against the poliomyelitis virus in the patients’
blood each time. The results are shown in the graph.
Page 4 of 45
Marks = 134 Time Allowed 165 minutes
Q1.
(a) A student prepared a stained squash of cells from the tip of an onion root and
observed it using an optical microscope.
During the preparation of the slide, he:
• cut the first 5 mm from the tip of an onion root and placed it on a glass slide
• covered this tip with a drop of stain solution and a cover slip
• warmed the glass slide
• pressed down firmly on the cover slip.
He identified and counted nuclei in different stages of the cell cycle.
Explain why the student:
1. used only the first 5 mm from the tip of an onion root.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
2. pressed down firmly on the cover slip.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
Figure 1 shows the cells the student saw in one field of view. He used this field of view to
calculate the length of time these onion cells spent in anaphase of mitosis.
Figure 1
Page 1 of 45
,(b) Scientists have found the mean length of time spent by onion cells in anaphase of
mitosis is 105 minutes. They also found the cell cycle of cells in the onion root
shown in Figure 1 takes 1080 minutes.
32 whole cells are shown in Figure 1.
Use this information and Figure 1 to calculate the length of time the cells of this
onion root are in anaphase and then calculate the percentage difference between
your answer and the mean length of time found by the scientists.
Show your working.
Answer = ____________________ %
(2)
(c) Tick (✓) the name given to the division of cytoplasm during the cell cycle.
A Binary fission
B Cytokinesis
C Phagocytosis
D Segregation
Page 2 of 45
, (1)
(d) Describe and explain what the student should have done when counting cells to
make sure that the mitotic index he obtained for this root tip was accurate.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
(e) A scientist treated growing tips of onion roots with a chemical that stops roots
growing. After 24 hours, he prepared a stained squash of these root tips.
Figure 2 is a drawing showing the chromosomes in a single cell observed in the
squash of one of these root tips in anaphase. This cell was typical of other cells in
anaphase in these root tips.
Figure 2
Use all of this information to suggest how the chemical stops the growth of roots.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Page 3 of 45
, ___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(3)
(Total 10 marks)
Q2.
(a) What is an antigen?
___________________________________________________________________
___________________________________________________________________
(2)
(b) What is an antibody?
___________________________________________________________________
___________________________________________________________________
(2)
Poliomyelitis is an infection caused by a virus.
A doctor vaccinated a group of patients against poliomyelitis. He gave each patient two
doses of vaccine, 3 months apart.
An immunologist tested three samples of blood from each of the patients:
• (sample 1) taken 2 weeks before the first dose of vaccine
• (sample 2) taken 2 weeks after the first dose of vaccine
• (sample 3) taken 2 weeks after the second dose of vaccine.
He measured the concentration of antibodies against the poliomyelitis virus in the patients’
blood each time. The results are shown in the graph.
Page 4 of 45
