Cell cycle (mitosis and meiosis) AQA AS Biology EXAM QUESTIONS

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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
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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 of the treated cells at stage B after the cell
began dividing again.
(i) What has happened to the chromosome number?
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(1)
(ii) Suggest an explanation for the change in the chromosome number.
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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 events during interphase which prepare a cell for mitosis.
1 ...................................................................................................................
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2 ...................................................................................................................
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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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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 from the unfertilised egg cells.
1 ...................................................................................................................
2 ...................................................................................................................
(2)
(f) Only 30% of the cloned cells successfully developed into embryos.
Suggest a reason for this low success rate.
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(1)
(Total 7 marks)
Q4.…read more

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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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Total 6 marks)
Q5. (a) The drawing shows a stage of mitosis in an animal cell.
(i) Name this stage of mitosis.
.............................................................................................................
(1)
(ii) Describe and explain what happens during this stage which ensures that two
genetically identical cells are produced.
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(2)
(b) The graph shows the relative amounts of DNA per cell during two successive cell
divisions in an animal.…read more

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What stage of the cell cycle is shown by X
.............................................................................................................
.............................................................................................................
(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 would you expect to be present in a gamete formed
in this animal as a result of meiosis?
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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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(4)
(b) Describe the behaviour of chromosomes during mitosis and explain how this results
in the production of two genetically identical cells.
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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 drugs could be
useful in the treatment of cancer.
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(2)
(Total 13 marks)
Q7. It is difficult to get rid of dandelions from a garden because small pieces of the root
are able to grow into new plants if left behind in the soil.…read more

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