Practise Meiosis. 16 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Human body cells contain 46 chromosomes. How many chromosomes are there in a human sperm cell?
23
State one similarity between mitosis and meiosis in what happens to the DNA before either type of division begins.
The DNA (genetic information) is copied before the cell divides, in both types of division
The stages below, involving cell division, happen during human reproduction, but they are in the wrong order. A Mitosis produces the millions of cells of a growing embryo. B Meiosis in the ovaries and testes produces gametes (eggs and sperm). C Fertilisation restores the full number of chromosomes. D The fertilised egg (zygote) begins to divide. Write the letters in the correct order.
B, C, D, A
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Gametes are produced by a type of cell division called meiosis.
(a) Where does meiosis take place in the human body? Tick (✓) one box.[1]
In the brain
In the ovaries and testes
In the skin
In the stomach
(b) How many cells are produced when one cell divides by meiosis? Tick (✓) one box.[1]
1
2
4
8
(c) Human body cells contain 46 chromosomes. How many chromosomes are there in a human sperm cell?[1]
(d) After fertilisation, the fertilised egg divides many times to form an embryo. Name the type of cell division involved.[1]
Show the answer and mark scheme
(a)Answer: In the ovaries and testes
(b)Answer: 4
(c)Answer: 23
23
(d)Answer: Mitosis
mitosis
Question 2Medium7 marks
Cells in reproductive organs divide by meiosis to form gametes.
(a) Describe what happens when a cell divides by meiosis.[3]
(b) Explain why it is important that gametes contain half the number of chromosomes of a body cell.[2]
(c) Describe what happens to the fertilised egg as it develops into an embryo.[2]
Show the answer and mark scheme
(a)Answer: Copies of the genetic information are made; the cell divides twice to form four gametes, each with a single set of chromosomes; the gametes are all genetically different
copies of the genetic information / chromosomes are made
the cell divides twice
four gametes are formed, each with a single set of chromosomes / half the number of chromosomes
the gametes are all genetically different from each other
(b)Answer: When two gametes join at fertilisation the normal number of chromosomes is restored; otherwise the number would double every generation
(so that) when gametes join at fertilisation the normal / full number of chromosomes is restored
otherwise the chromosome number would double in each generation
(c)Answer: It divides by mitosis so the number of cells increases, and the cells differentiate as the embryo develops
divides by mitosis / the number of cells increases
the cells differentiate / become specialised
Question 3Hard8 marks
A cell in a man's testis contains 23 pairs of chromosomes. In each pair, one chromosome came from the man's mother and one came from his father.
(a) Explain why the sperm cells made from this cell by meiosis are genetically different from each other.[2]
(b) A cell of another species contains only two pairs of chromosomes. The chromosomes from the mother are labelled 1M and 2M, and those from the father are labelled 1F and 2F. List all the different combinations of chromosomes that could be found in the gametes.[2]
(c) Explain why two brothers who are not identical twins are genetically different from each other.[2]
(d) Identical twins form when a very early embryo splits into two. Explain why identical twins are genetically identical.[2]
Show the answer and mark scheme
(a)Answer: Each sperm receives only one chromosome from each pair, and which chromosome of each pair goes into a sperm is random, so there are many different combinations
each gamete receives one chromosome from each pair
which chromosome (from the mother or father) goes into each gamete is random, giving different combinations
(b)Answer: 1M 2M; 1M 2F; 1F 2M; 1F 2F
any two correct combinations
all four correct with no extras: 1M 2M, 1M 2F, 1F 2M, 1F 2F
(c)Answer: Each brother developed from a different egg and a different sperm; these gametes were genetically different, and which gametes fused was random
each developed from a different egg and sperm / gametes are genetically different
fertilisation is random / which sperm fertilises which egg is random
(d)Answer: Both develop from the same fertilised egg, and all the cells are produced by mitosis, which produces genetically identical cells
they come from the same fertilised egg / zygote
the cells are produced by mitosis (which makes genetically identical cells)