Reproduction – Asexual Reproduction SS2 Biology Lesson Note

Reproduction is the ability of living organisms to produce offspring i.e. new individuals of their kind or the same species. Reproduction guarantees the continuity of life of all species of organisms. There are two forms of reproduction, They are sexual reproduction and asexual reproduction

1. ASEXUAL REPRODUCTION

In asexual reproduction, an individual produces an offspring by itself i.e. only one parent is present. There is no fusion of nuclei and the cells that give rise to the offspring usually divide using mitosis. As a result, asexual reproduction often produces offspring which are identical to the parent. In rare cases, the offspring may not be identical due to mutation.

Asexual reproduction is common among simple organisms and flowering plants. Forms of asexual reproduction include the following:

1. Fission: It is commonly found in bacteria and protists. The parent organism simply divides into two or more parts, each of which can exist by itself. e.g. binary fission in bacteria.
2. Budding: In budding, the offspring develops as an outgrowth of the parent. The bud may form on an internal or external surface of the parents. Internal buds are formed in some sponges and released when the parent dies. External buds occur in Hydra and Coral polyps. The buds break off from the parent without causing any injury and lead an independent life.

iii. Spore Formation: Spores are small unicellular bodies which are produced in large numbers. They are small, light and easily dispersed by air. Under favourable conditions, each spore can develop into an independent organism. Spores are commonly produced by Bacteria, Fungi, Protists, Algae, Mosses and Ferns.

1. Fragmentation: In this type of asexual reproduction a part of an organism breaks up or fragments from the parent organism and gives rise to a new individual. It is a form of regeneration that occurs in simple organisms like algae, coelenterates and sponges.
2. Vegetative propagation: It occurs mainly in higher plants where a new plant grows from any portion of an old one other than the seeds. This is the formation of new individuals or plants by a vegetative portion of the plant such as roots, stems and leaves. They are tubers, corns, bulbs, rhizomes, etc