Reproduction: Sexual and Asexual — AQA GCSE Biology
Organisms reproduce sexually, asexually, or sometimes both. The two types have different advantages.
Sexual reproduction
- Involves the fusion of male and female gametes (sperm and egg in animals; pollen and egg cells in plants).
- Gametes are produced by meiosis, so there is a mixing of genetic information.
- Offspring are genetically different from each other and from the parents — there is variation.
Asexual reproduction
- Involves only one parent and no gametes (no fusion).
- Uses mitosis, so offspring are genetically identical clones of the parent.
- Examples: bacteria, many plants (e.g. strawberry runners, bulbs), some animals, and fungi.
Advantages and disadvantages
| Sexual | Asexual | |
|---|---|---|
| Variation | yes (helps survival if environment changes) | no |
| Number of parents | two | one |
| Speed | slower | fast |
| Energy/finding a mate | needed | not needed |
Organisms that use both
Some organisms reproduce both ways depending on conditions:
- Malarial parasites reproduce asexually in humans and sexually in the mosquito.
- Many plants produce seeds sexually but also reproduce asexually (e.g. runners, bulbs).
- Fungi release spores (asexually) or reproduce sexually.
Exam tips
- Sexual = two parents, gametes, meiosis, variation.
- Asexual = one parent, no gametes, mitosis, identical clones.
- Variation is the key advantage of sexual reproduction.
- Speed and no need for a mate are advantages of asexual reproduction.