Cell Division (Edexcel A (SNAB) A Level Biology)

Exam Questions

47 mins5 questions
1a
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4 marks

The diagram below shows a micrograph of cells in actively dividing tissue from the root tip of a plant.

VOYEbqCd_image

(i)

Name the type of cell division shown in the diagram.

(1)

(ii)

Give evidence from the diagram and information provided to justify your answer for part (i).

(3)

1b
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3 marks

Complete the sentences below about the cells in the diagram shown in part (a)

Cell V is in ___________________ stage of cell division. This is because...

Cell W is in __________________ stage of cell division. This is because...

Cell X is in ___________________ stage of cell division. This is because...

1c
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2 marks

The mitotic index is used to calculate the proportion of cells undergoing mitosis.

A student prepared a root tip squash and observed the cells under a light microscope. They counted a total of 57 cells and of these 36 were counted as undergoing mitosis. 

Calculate the mitotic index of the dividing root tissue. Give your answer as a percentage.

1d
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3 marks

The student further examined cells in the root tip under the microscope, and obtained the following data:

Stage of mitosis Number of cells
Interphase 98
Prophase 45
Metaphase 26
Anaphase 12
Telophase 8
(i)

Calculate the percentage of these cells in which the chromosomes are visible and would consist of a pair of chromatids joined together. Give your answer to three significant figures.

(2)

(ii)

Explain why, during this practical, the root tip must be firmly squashed.

(1)

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2a
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2 marks

Mitosis is an essential process for living organisms. 

Give two reasons why mitosis is so important.

2b
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6 marks

Describe the appearance and behaviour of chromosomes during mitosis.

2c
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1 mark

The diagram shows chromosomes at different stages of the cell cycle.

Of the cells in mitosis, place the stages in the correct order by completing the table below. The first stage has been done for you. 

micrograph

Stage of mitosis Letter
1 E
2  
3  
4  

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3a
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2 marks

A sample of tissue taken from a liver biopsy was analysed. Some of the cells had 6.4 units of DNA, others had only 3.2 units.

Explain the difference in DNA units of these cells.

3b
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2 marks

One of the cells from the sample was analysed. The time required for the cell to complete one full cell cycle was 23 hours and 40 minutes. 

Calculate the time required for this cell to multiply to produce eight cells.

3c
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2 marks

The graph below the the mass of DNA during the cell cycle

Mass of DNA throughout Cell Cycle

Use your knowledge of the cell cycle to explain the shape of the graph between:

(i)

5 and 8 hours

(1)

(ii)

13 and 16 hours

(1)

3d
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1 mark

Apart from an increase in the mass of DNA, give one process which occurs during hours 0 to 14 which enables nuclear division to occur.

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4a
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3 marks

Scientists investigated the effect of mitotic inhibitor drugs which prevent microtubule formation. One such drug is Vincristine; a chemotherapy drug that binds irreversibly to microtubules and spindle proteins in S phase of the cell cycle and interferes with the formation of the mitotic spindle.

The scientists found that Vincristine was effective at halting the cell cycle in both healthy and cancerous cells.

Explain why preventing the formation of spindle fibres stopped the cell cycle.

4b
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1 mark

Explain why Vincristine can be used as a treatment for cancer even though it affects some healthy cells.

4c
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3 marks

Vincristine was given to a cancer patient. It was given once every three weeks, starting at time 0.

The graph shows the changes in the number of healthy cells and cancer cells during twelve weeks of treatment.


cancer-cells

Using the graph calculate the number of cancer cells present at week 12 as a percentage of the original number of cancer cells.

4d
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2 marks

Describe two differences in the effect of Vincristine on cancer cells, compared with healthy cells.

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5a
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5 marks

Cells divide by mitosis to form new cells.

Describe the changes that occur within the cell between the beginning of prophase and the end of metaphase.

5b
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2 marks

The diagram below shows a chromosome in a cell undergoing mitosis.

5-2-fig-1-1

(i)

Identify structure P.

(1)

(ii)

Describe the role of structure P during mitosis.

(1)

5c
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2 marks

From the diagram in part (b): 

(i)

Identify the stage of mitosis that the chromosome could be in.

(1)

(ii)
State a reason for your answer to part (i).
(1)
5d
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1 mark

Explain why it is important for DNA replication to take place before mitosis can occur.

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