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Page 1

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Q1. The diagrams show four stages of mitosis.




(a) (i) Name stage A.

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(1)




(ii) Starting with stage C, give the stages A
to D in the correct order.

C ............ ............. .............
(1)




(iii) .
Describe and explain the appearance of one of the chromosomes in stage B…

Page 2

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(2)




(b) Colchicine is a substance that prevents the formation of the spindle in mitosis.
Dividing cells were treated with colchicine. This stopped them dividing. After a few
hours, the colchicine was removed and the cells began to divide again. The diagram
shows the chromosomes from one…

Page 3

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Q2. (a) The photographs show two stages in mitosis of a plant cell.




A B

Name stages A and B
. In each case describe what is happening to the
chromosomes.

(i) Stage A ....................................

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(2)




(ii) Stage B ....................................

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(2)




(b) Describe two…

Page 4

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Q3. A clone of frogs was produced by nuclear transfer. This procedure is summarised in
the diagram.




(a) What is a clone?

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(1)




(b) Name the type of cell division occurring in a developing embryo.

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Page 5

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(1)




(c) The embryo cells used are from an early stage of development. Explain why.

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(1)




(d) What would be the colour of the cloned offspring? Explain your answer.

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(1)




(e) Give two differences between the nuclei removed from the embryo cells and the
nuclei discarded…

Page 6

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(a) Draw a diagram to show

(i) this cell during anaphase of mitosis;




(2)




(ii) the chromosomes in a gamete produced from this cell by meiosis.




(2)




(b) Explain why meiosis is important in sexual reproduction, apart from producing
gametes that are genetically different.

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Page 7

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(2)
(Total 6 marks)




Q5. (a) The drawing shows a stage of mitosis in an animal cell.




(i) Name this stage of mitosis.

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(1)




(ii) Describe and explain what happens during this stage which ensures that two
genetically identical cells are produced.

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Page 8

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(i) ?
What stage of the cell cycle is shown by X

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(1)




(ii) ne p
Apart from an increase in the amount of DNA, give o rocess which occurs
which enables nuclear division to occur.
during stage X

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(1)




(iii) How many units of DNA…

Page 9

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Metaphase 15
Anaphase 10
Telophase 42


Give one piece of evidence from the table which indicates that these cells are
multiplying rapidly.

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(1)
(Total 7 marks)




Q6. (a) Describe and explain how the structure of DNA results in accurate replication.

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Page 10

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(7)




(c) A cancerous tumour is formed by uncontrolled mitotic division. This results in a
mass of cells with an inadequate blood supply. Drugs are being developed which
only kill cells in a low oxygen environment. Suggest how these…

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