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Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
The key difference
Sexual reproduction involves the fusion of two gametes from two parents, producing genetically varied offspring. Asexual reproduction involves one parent and produces genetically identical offspring (clones) without gamete fusion.
These two fundamental strategies for producing offspring have very different genetic outcomes. Sexual reproduction generates variation, which is essential for natural selection, while asexual reproduction is faster and requires no mate. Both strategies have advantages, and some organisms can use both depending on conditions.
Feature
Sexual Reproduction
Asexual Reproduction
Number of parents
Two
One
Gametes involved?
Yes: fusion of male and female gametes (fertilisation)
No gametes: no fertilisation
Genetic variation in offspring
Yes: offspring are genetically different from parents and from each other
No: offspring are genetically identical to the parent (clones)
Type of cell division
Meiosis (to produce gametes) then mitosis (growth of offspring)
Mitosis only
Speed
Slower: must find a mate, fertilisation takes time
Faster: no need to find a mate
Number of offspring
Usually fewer
Can produce many offspring quickly
Examples
Humans, flowering plants (pollination and seed formation)
Produces genetic variation: some offspring may be better adapted to changing environments
Variation allows natural selection to occur, driving evolution
Reduces the spread of genetic diseases (harmful alleles may not be inherited by all offspring)
Advantages of asexual reproduction:
Only one parent needed: no energy wasted finding a mate
Faster: can colonise new habitats quickly
All offspring carry the successful parent's genes (if the parent is well-adapted, so are all offspring)
Useful in stable, unchanging environments
The disadvantage of asexual reproduction is that all offspring are genetically identical. If the environment changes (e.g. A new disease appears), all individuals are equally vulnerable and the entire population could be wiped out.
Organisms That Do Both
Some organisms can switch between sexual and asexual reproduction:
Fungi: can reproduce asexually by spores or sexually when conditions are harsh
Strawberry plants: produce runners (asexual) and also flowers for sexual reproduction
Potatoes: grow tubers (asexual) but also produce flowers and seeds (sexual)
Typically, organisms use asexual reproduction when conditions are favourable (rapid colonisation) and switch to sexual reproduction when conditions are challenging (genetic variation increases the chance that some offspring survive).
Try a comparison question (3 marks)
A farmer grows a field of genetically identical crop plants produced by asexual reproduction. Explain why this could be a disadvantage if a new fungal disease appears. [3]
Show the answer and marking guidance
All plants are genetically identical / clones / no genetic variation
If one plant is susceptible to the fungal disease, all plants will be equally susceptible
The entire crop could be destroyed / no individuals with resistance to survive and reproduce
Original Cambridge-style practice written for this site.
Common comparison mistakes
When answering a compare question, write matched pairs rather than two separate descriptions.
Saying asexual reproduction involves meiosis: it only uses mitosis
Claiming sexual reproduction always requires two separate organisms: self-pollination in plants involves one organism
Forgetting that variation from sexual reproduction is important for natural selection
Stating that asexual reproduction produces "no offspring quickly" when it actually produces many offspring quickly