4.6.1.3Pros and cons of sexual and asexual reproduction
AQA GCSE Biology Foundation (8461), Foundation tier · Inheritance, variation and evolution › Reproduction
Practise Pros and cons of sexual and asexual reproduction. 6 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
The advantages and disadvantages of sexual and asexual reproduction, and organisms that use both. This is in GCSE Biology only, not in Combined Science. It is asked as 'give an advantage', 'suggest why' or a 4 to 6 mark 'evaluate' question about an organism you may not have met.
Key facts
Sexual: variation → survival advantage if the environment changes (natural selection)
Selective breeding speeds up natural selection, e.g. to increase food production
Asexual: one parent; no need to find a mate (time and energy efficient); faster; many identical offspring when conditions are favourable
Asexual disadvantage: no variation, so one change (e.g. a new disease) can affect the whole population
Malarial parasite: asexual in the human host, sexual in the mosquito
Fungi: asexual by spores, sexual to give variation
Strawberries (runners) and daffodils (bulb division) reproduce asexually, and sexually by seeds
Notes
Advantages of sexual reproduction
It produces variation in the offspring.
If the environment changes, variation gives a survival advantage: some individuals are likely to have characteristics that help them survive, and these are passed on by natural selection.
Humans can speed up natural selection by selective breeding, for example to increase food production.
Advantages of asexual reproduction
Only one parent is needed.
It is more time and energy efficient, because there is no need to find a mate.
It is faster than sexual reproduction.
Many identical offspring can be produced when conditions are favourable.
The disadvantages
Sexual reproduction: two parents are needed, finding a mate takes time and energy, and it is slower.
Asexual reproduction: there is no variation, so if conditions change (for example a new disease appears), the whole population is equally affected and could be wiped out.
Organisms that use both methods
Malarial parasites reproduce asexually in the human host, but sexually in the mosquito.
Many fungi reproduce asexually by spores, but also reproduce sexually to give variation.
Many plants produce seeds by sexual reproduction, but also reproduce asexually: strawberry plants by runners and daffodils by bulb division.
Any organism can appear in a question, so apply the same advantages and disadvantages to the information you are given.
How to answer each type of question
Give one advantage of each type
1 to 2 marksGrade 4
Asexual: choose from one parent, faster, no need to find a mate, many offspring when conditions are favourable.
Sexual: variation, so a better chance of survival if the environment changes.
Example. Daffodils can reproduce sexually by seeds and asexually by bulb division. (a) Give one advantage to the daffodil of reproducing asexually. (b) Give one advantage to the daffodil of reproducing sexually. [2 marks]
Show the model answerHide the model answer
(a) Any one: only one parent is needed / it is faster / no need for a mate / many identical plants can be produced when conditions are favourable (1) (b) It produces variation, so some offspring may survive if the environment changes (1)
Don’t lose marks
Saying sexual reproduction is better 'because it gives variation' without explaining why variation helps (survival if the environment changes).
Saying asexual reproduction 'uses less energy' without the reason: there is no need to find a mate.
Mixing up the malarial parasite: it reproduces asexually in the human and sexually in the mosquito.
Calling runners or bulbs sexual reproduction. They are asexual; seeds come from sexual reproduction.
More tips
Memory tricks
Asexual in four words: one parent, no mate, fast, many copies.
Sexual means variety; variety means survival when things change.
Organisms that do both: Malaria (asexual in humans, sexual in mosquitoes), Fungi (spores and sex), Plants (strawberry runners, daffodil bulbs).
Exam technique
In 'evaluate' questions, give advantages and disadvantages, then end with a conclusion.
Apply your answer to the organism in the question (its food supply, seasons, environment) instead of just listing facts.
Link variation to natural selection: variation → some survive a change → they breed → they pass on their alleles.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 4
Give an advantage of asexual reproductionOnly one parent is needed, so there is no need to find a mate.
Grade 4
Give an advantage of sexual reproductionIt produces variation in the offspring.
Grade 5
Explain why variation helps a species surviveIf the environment changes, some individuals are likely to have characteristics that help them survive, by natural selection.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Some organisms reproduce sexually, some reproduce asexually and some can reproduce in both ways. Give one advantage of sexual reproduction.
It produces variation in the offspring
Give one advantage of asexual reproduction when conditions are favourable and stable.
It allows an organism to reproduce rapidly, without needing to find a mate
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
Some organisms reproduce sexually, some reproduce asexually and some can reproduce in both ways.
(a) Which two are advantages of asexual reproduction? Tick (✓) two boxes.[2]
It involves meiosis
It is faster than sexual reproduction
It needs a mate
Offspring show variation
Only one parent is needed
(b) Give one advantage of sexual reproduction.[1]
(c) Daffodils can reproduce asexually by bulb division. Name a plant that reproduces asexually using runners.[1]
(d) Which organism reproduces asexually in the human host but sexually in the mosquito? Tick (✓) one box.[1]
HIV
Malarial parasite
Rose black spot fungus
Salmonella bacterium
Show the answer and mark scheme
(a)Answer: It is faster than sexual reproduction; Only one parent is needed
(b)Answer: It produces variation in the offspring
produces variation (in the offspring)
(c)Answer: Strawberry
strawberry
(d)Answer: Malarial parasite
Question 2Medium7 marks
A fruit grower has a strawberry plant that produces very large, sweet fruit. Strawberry plants reproduce sexually by seeds and asexually by runners.
(a) Explain why the grower produces new plants from runners rather than from seeds.[3]
(b) Give one disadvantage of growing a whole field of strawberries that were all produced from runners of one plant.[2]
(c) Plant breeders use sexual reproduction when they want to produce new varieties of strawberry. Explain why.[2]
Show the answer and mark scheme
(a)Answer: Runners are produced asexually, so the new plants are clones with the same large, sweet fruit; plants from seeds show variation and may not have these characteristics; runners are also quicker
runners are produced by asexual reproduction / mitosis, so the new plants are genetically identical (clones)
so all the new plants will produce large, sweet fruit
plants from seeds show variation (so may not have the desired characteristics)
producing plants from runners is faster
(b)Answer: There is no variation, so if a disease or change in the environment affects one plant it will affect them all
no (genetic) variation
(so) all could be killed by the same disease / all affected if the environment changes
(c)Answer: Sexual reproduction produces variation, so offspring with new combinations of characteristics can be selected and bred
sexual reproduction produces variation / new combinations of alleles
(so) offspring with the desired characteristics can be selected (and bred)