Sexual and asexual reproduction

In a nutshell

Organisms can reproduce sexually or asexually. Sexual reproduction creates variation as offspring contain a mixture of both parents' genes. Asexual reproduction produces clones of the one parent. Both methods have their own advantages. Some organisms can use both types of reproduction.

Sexual and asexual reproduction

Definition

Sexual reproduction requires two parents and produces offspring that are genetically varied as they contain a mixture of both parents genes. Asexual reproduction only requires one parent and there is no genetic variation as the offspring are clones of the parent which means all offspring are genetically identical to each other and the parent.

Advantages

Sexual reproduction

Sexual reproduction produces variation within the offspring which is an advantage as it increases the chance of the species surviving a change in their environment.

The change may kill some individuals in the species but because of variation, some may have a characteristic that makes them better suited to the new environment so they are more likely to survive and pass on this beneficial characteristic to their offspring. This is natural selection.

Selective breeding can be used to speed up the process of natural selection. Individuals with the desirable characteristics are bred to produce offspring that will also have the desirable characteristics. Food production can be increased this way as animals that produce a lot of meat can be bred to produce even more meat.

Asexual reproduction

Asexual reproduction requires one parent so there is less energy required to carry out the process. There is no need to find a mate and the process is much faster. Under favourable conditions, lots of clones can be produced to take advantage of the favourable conditions.

Some organisms use both methods

Organism	Explanation
Malaria	Malaria is caused by a parasite that is spread by mosquitoes. The parasite is transferred from the mosquito to humans when they bite. The parasite reproduces sexually in the mosquito, then asexually in the human host.
Fungi	Fungi release spores that become new fungi when they land. Spores can be produced asexually to make clones of the original fungus or they can be produced sexually. This will create variation and it often happens in response to an unfavourable environmental change.
Plants	Plants can produce seeds sexually and they can also reproduce asexually. Some plants, like strawberries, reproduce asexually by producing runners. These are stems that run horizontally on the soil from the parent plant. New strawberry plants form along the runners that are genetically identical to the parent strawberry plant. Asexual reproduction can also happen in bulbs. Onions and garlic plants can form as new bulbs from the main parent bulb. They will grow into new identical plants.