There are two types of reproduction in living organisms: sexual reproduction, and asexual reproduction. Some organisms are capable of both.

Sexual reproduction

Sexual reproduction involves two individuals who, through the process of reproduction, combine their sex cells (called gametes) to form a new individual with characteristics of both parents. This union (or fusion) of gametes is called fertilisation, and results in the production of a unique individual. With the exception of identical twins no two organisms resulting from sexual reproduction have exactly the same features.

Can different species mate?

Sometimes two different species mate to produce an offspring such as a liger or a geep. These are known as hybrids.

Hybrids are sometimes fertile, i.e. able to produce offspring, but more often they are sterile. For example, a mule is a sterile hybrid of a donkey and a horse.

Asexual reproduction

Asexual reproduction requires only one parent and does not involve the union of gametes. It results in offspring who are the same as the parent.

There are five methods of asexual reproduction: budding, vegetative propagation, fragmentation, spores, and fission.

Fission occurs in single-celled organisms such as bacteria and protozoa. In fission the parent cell simply divides into two equal parts, each of which develops into a new organism.

Fragmentation is like fission but occurs in multicellular organisms, particularly animals like worms.

Budding occurs in both single-celled and multicellular organisms. A bud grows off a parent to become a new individual.

Spores such as seen on the underside of fern fronds contain a number of reproductive cells which will grow into new individuals if they meet suitable conditions.

Some flowering plants are able to reproduce asexually as well as sexually. They are able to reproduce by growing parts which separate from the parent plant to form new plants. The process is known as vegetative propagation. For example, strawberry plants send out a ‘runner’ which puts down roots and grows into a new strawberry plant. As only one parent is involved it is a form of asexual reproduction. Each strawberry plant will look like the next.

We can make plants reproduce asexually. A cutting taken from one plant and placed in the soil may grow roots from the cut end of the stem. The cut branch becomes a new plant.