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4.6.1.1Sexual and asexual reproduction

AQA GCSE Combined Science (8464), Higher tier · Biology › Inheritance, variation and evolution › Reproduction

Practise Sexual and asexual reproduction. 12 exam-style questions 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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Revision notes

How sexual reproduction (two parents, fusion of gametes, variation) differs from asexual reproduction (one parent, no gametes, clones). It is usually tested with short recall questions, 'compare' questions and 'explain why the offspring are identical' questions.

Grade by grade

What you need to be able to do, from the first marks up to the top grade.

  1. 3
    Name the gametes in animals and plantsAnimals: sperm and egg cells. Flowering plants: pollen and egg cells.
  2. 3
    State how many parents each type needsSexual reproduction needs two parents; asexual reproduction needs only one.
  3. 4
    Define sexual reproductionThe joining (fusion) of a male gamete and a female gamete.
  4. 5
    Name the cell division each type usesGametes are made by meiosis; asexual reproduction involves only mitosis.
  5. 6
    Explain why sexually produced offspring varyGenetic information from two parents is mixed, so each offspring gets a different combination of alleles.
  6. 6
    Explain why asexual offspring are clonesThere is no fusion of gametes and no mixing of genetic information, and only mitosis is involved.

Notes

Sexual reproduction

  • Sexual reproduction involves the joining (fusion) of a male gamete and a female gamete.
  • In animals the gametes are sperm and egg cells. In flowering plants they are pollen and egg cells.
  • Gametes are made by meiosis, so each gamete has half the normal number of chromosomes.
  • Genetic information from the two parents is mixed, so the offspring show variation: they are genetically different from each other and from their parents.

Asexual reproduction

  • Asexual reproduction involves only one parent.
  • There is no fusion of gametes and no mixing of genetic information.
  • Only mitosis is involved, so the offspring are genetically identical to the parent and to each other. Genetically identical offspring are called clones.
  • Examples: strawberry plants growing new plants on runners, and daffodils forming new bulbs.

Side by side

  • Parents: sexual needs two; asexual needs one.
  • Gametes: sexual uses gametes made by meiosis; asexual uses no gametes.
  • Cell division: sexual involves meiosis (to make gametes); asexual involves only mitosis.
  • Offspring: sexual gives genetically different offspring (variation); asexual gives genetically identical offspring (clones).

Cheatsheet

  • Gamete = sex cell with half the normal number of chromosomes
  • Animal gametes: sperm and egg. Flowering plant gametes: pollen and egg
  • Sexual reproduction = fusion of male and female gametes → mixing of genetic information → variation
  • Asexual reproduction = one parent, no gametes, no mixing → clones
  • Meiosis makes gametes; asexual reproduction involves only mitosis
  • Clone = genetically identical offspring

How to answer each type of question

Recall: name the gametes or the type of cell division

1 mark each3
  1. Learn the pairs: sperm and egg (animals), pollen and egg (flowering plants).
  2. Meiosis makes gametes; mitosis is the only cell division in asexual reproduction.

Example. (a) Name the male gamete in a flowering plant.
(b) Name the type of cell division involved in asexual reproduction.

Show the model answer
(a) Pollen (1)
(b) Mitosis (1)

Compare sexual and asexual reproduction

3 to 4 marks5
  1. Make every point a comparison: 'sexual ... whereas asexual ...'.
  2. Cover the number of parents, gametes, mixing of genetic information and whether the offspring vary.
  3. Use the key words fusion, gametes, variation and clones.

Example. Compare sexual reproduction with asexual reproduction. [4 marks]

Show the model answer
Sexual reproduction needs two parents, whereas asexual reproduction needs only one (1). Sexual reproduction involves the fusion of gametes, but asexual reproduction involves no gametes (1). In sexual reproduction genetic information from two parents is mixed, but in asexual reproduction there is no mixing (1). So sexual reproduction produces variation in the offspring, whereas asexual reproduction produces genetically identical offspring (clones) (1).
Also allow: sexual involves meiosis, whereas asexual involves only mitosis.

Explain why the offspring are identical (or different)

2 marks6
  1. Say which type of reproduction it is and why (one parent, no gametes).
  2. Give the reason: no mixing of genetic information and only mitosis (or, for sexual, mixing of genetic information from two parents).
  3. Finish with the result: clones or variation.

Example. A gardener grows five new strawberry plants from the runners of one parent plant.
Explain why the five new plants are genetically identical to the parent plant. [2 marks]

Show the model answer
Growing plants from runners is asexual reproduction, with only one parent and no fusion of gametes (1). Only mitosis is involved, so there is no mixing of genetic information and the new plants have exactly the same genetic information as the parent (1).

Shortcuts and memory tricks

  • A for Asexual, A for 'A copy': one parent, no gametes, clones.
  • Count the parents: two parents always means gametes, fusion and variation.
  • Mitosis makes identical cells (growth, repair, asexual reproduction). Meiosis makes gametes.

Where marks are lost

  • Saying asexual reproduction uses meiosis. It involves only mitosis.
  • Writing 'the genes are mixed' without saying that the genetic information comes from two parents.
  • Saying pollen is the female gamete. Pollen is male; the egg cell is female.
  • Calling asexual offspring 'similar' or 'the same'. Use 'genetically identical' or 'clones'.

Exam technique

  • In 'compare' questions, give both sides of every point (sexual ... whereas asexual ...). A one-sided statement often gets no credit.
  • Key words examiners look for: fusion, gametes, mixing of genetic information, variation, clones, mitosis, meiosis.
  • If the question describes an unfamiliar organism, look for clues: one parent and no gametes means asexual reproduction.

Quick recall

Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.

Organisms can reproduce sexually or asexually. How many parents are involved in asexual reproduction?
One
Describe how the genetic information in the anemones produced by method 1 compares with the genetic information in the parent.
It is identical; they are clones of the parent
A seed germinates and grows into a plant.
Name the type of cell division that produces the new cells as the plant grows, and describe what happens to the cells as the plant develops.
Mitosis; the cells differentiate / become specialised
Complete the sentences.
Sexual reproduction involves the joining (fusion) of male and female .......... .
In sexual reproduction there is mixing of genetic information, which leads to .......... in the offspring.
gametes; variety (variation)

Sample questions

Written for this site in the style of AQA exam questions. They are not taken from real past papers.

Question 1Easy5 marks
Organisms can reproduce sexually or asexually.
(a) Which type of cell division is involved in asexual reproduction?
Tick (✓) one box.[1]
  • Fertilisation
  • Meiosis
  • Mitosis
  • Pollination
(b) Which two are gametes in flowering plants?
Tick (✓) two boxes.[2]
  • Egg cell
  • Pollen
  • Root hair cell
  • Seed
  • Xylem cell
(c) How many parents are involved in asexual reproduction?[1]
(d) Asexual reproduction produces offspring that are genetically identical to the parent.
What name is given to genetically identical offspring?[1]
Show the answer and mark scheme
(a) Answer: Mitosis
(b) Answer: Egg cell; Pollen
(c) Answer: One
  • one / 1
(d) Answer: Clones
  • clones
Question 2Medium6 marks
Sexual and asexual reproduction produce offspring in different ways.
(a) Give two differences between sexual reproduction and asexual reproduction.[2]
(b) Explain why offspring produced by sexual reproduction show variation.[2]
(c) Explain why offspring produced by asexual reproduction are genetically identical to their parent.[2]
Show the answer and mark scheme
(a) Answer: Sexual reproduction involves two parents and the fusion of gametes; asexual involves one parent and no gametes. Sexual reproduction mixes genetic information and gives variation; asexual produces clones
  • sexual involves two parents but asexual involves only one
  • sexual involves the fusion / joining of gametes but asexual does not
  • sexual produces variation / genetically different offspring but asexual produces clones
  • sexual involves meiosis (to make gametes) but asexual involves only mitosis
(b) Answer: Genetic information from two parents is mixed when gametes fuse, and the gametes are genetically different from each other
  • genetic information from two parents is mixed (when gametes fuse)
  • gametes (made by meiosis) are genetically different from each other
(c) Answer: There is only one parent and no fusion of gametes, so there is no mixing of genetic information; only mitosis is involved, which produces genetically identical cells
  • only one parent / no fusion of gametes / no mixing of genetic information
  • only mitosis is involved (which makes genetically identical cells)
Question 3Hard7 marks
Strawberry plants can reproduce sexually by producing seeds. They can also reproduce asexually by growing runners. A runner is a stem that grows along the ground and forms a new plant where it touches the soil.
(a) A gardener grew new plants from runners and from seeds of the same strawberry plant.
Compare the genetic information in the new plants grown from runners with that in the new plants grown from seeds.
Explain your answer in terms of the cell division and the cells involved.[5]
(b) A seed germinates and grows into a plant.
Name the type of cell division that produces the new cells as the plant grows, and describe what happens to the cells as the plant develops.[2]
Show the answer and mark scheme
(a) Answer: Plants from runners are genetically identical to the parent and to each other because they are formed by mitosis only. Plants from seeds are genetically different from the parent and from each other because the gametes are formed by meiosis and are all different, and fertilisation mixes genetic information (from two gametes)
  • plants from runners are genetically identical to the parent / each other (clones)
  • runners are produced by mitosis only / no gametes involved
  • plants from seeds are genetically different from the parent / each other
  • (because) gametes are produced by meiosis
  • (and) gametes are all genetically different
  • fertilisation / fusion of gametes mixes genetic information
(b) Answer: Mitosis; the cells differentiate / become specialised
  • mitosis
  • cells differentiate / become specialised

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