A strawberry plant sends out runners and new plants root along them. A bacterium splits in two. A potato tuber sprouts into a whole new plant. None of these needs a partner or gametes, and every offspring carries exactly the same genes as its parent. Weighing up when that is useful and when it is risky is Extended content.
Asexual reproduction is a process resulting in the production of genetically identical offspring from one parent. There are no gametes and no fertilisation, so the offspring (clones) have the same genes as the parent and as each other. Extended: it is fast and needs only one parent, but the lack of variation means a whole population can be wiped out by one change, such as a new disease.
In the lab, choose asexual (runners) and grow the offspring. One parent plant sends runners across the soil and nine new plants appear. Look at their flowers: every one is the same colour as the parent's.
Asexual offspring are not just similar to the parent: they are genetically identical. If you see variation between asexual offspring, it must be caused by the environment, not by their genes.
Four quick checks. Each correct answer earns XP and records this skill on your profile.
In the lab's asexual mode, how many parents produce the new strawberry plants?
Why are all the flowers on the asexual offspring the same colour as the parent's?
Extended: when a disease strikes the asexual clones in the lab, how many survive?
Which feature is shared by every type of asexual reproduction?
Exam questions often show a diagram or describe an organism and ask whether it reproduces asexually. Look for a single parent and new individuals growing from part of it.
| Organism | How it reproduces asexually |
|---|---|
| Bacteria | binary fission: one cell divides into two identical cells |
| Yeast | budding: a small bud grows out of the cell and breaks off |
| Fungi such as Mucor | spores made by one parent, spread by air |
| Strawberry, spider plant | runners (horizontal stems) with new plants along them |
| Potato | stem tubers; each "eye" can sprout into a new plant |
| Onion, daffodil | bulbs that divide to form new bulbs |
| Gardeners and growers | cuttings: a piece of stem is planted and grows roots |
Extended. Now press A disease strikes in the lab. With the asexual clones, the survivors reading is 0 of 9: none of them is resistant. With sexual reproduction some of the varied offspring survive.
| Advantages of asexual reproduction | Disadvantages | |
|---|---|---|
| Population in the wild | fast; only one parent needed, so an isolated individual can still reproduce; can colonise an area quickly while conditions suit it | no variation, so if the environment changes or a disease arrives, all may be killed; offspring may crowd and compete with the parent |
| Crop production | every plant keeps the good features of the parent (yield, flavour); uniform crop ripens together; quicker than growing from seed | a disease or pest that attacks one plant can destroy the whole crop; no new varieties arise for better yield |
Do not just write "it is quicker" or "there is no variation". Say why it matters: for example, no variation means no individual is likely to be resistant, so the whole population or crop could be lost.
Unlocks once the four checks above are done. Worth more XP, written to IGCSE Paper 2 and Paper 4 standard.
Which is the best description of asexual reproduction?
Which of these is an example of asexual reproduction?
Extended: a farmer grows a field of genetically identical banana plants. What is the main risk?
Extended: which is an advantage of asexual reproduction to a plant species in the wild?
This skill is now recorded on your profile. Keep the chain going.