Class 12 Biology



Reproduction: The biological process through which an organism gives rises to young ones (offspring) similar to itself, is called reproduction. The offspring grow, mature and produce new offspring. Thus, reproduction helps in continuity of species.

Types of Reproduction

  1. Asexual Reproduction
  2. Sexual Reproduction

Asexual Reproduction: When a single parent participates in reproduction, and gamete formation does not take place; it is called asexual reproduction. Offspring which are produced by means of asexual reproduction are identical or clones to their parent.

Sexual Reproduction: When two parents (of opposite sexes) participate in reproduction, and gamete formation takes place; it is called sexual reproduction. In some examples of sexual reproduction, a single parent may produce both the male and female gametes and participate in reproduction.

Types of Asexual Reproduction

binary fission

Binary Fission in Paramecium

This method is common in unicellular organisms. In this method, the mother cell undergoes mitotic cell division to produce two daughter cells. Protists and Monerans use binary fission for reproduction. The parental generation ceases to exist after binary fission, and the new generation comes into existence. Example: Amoeba, Paramecium, etc.

budding in yeast

Buddingh in Yeast

Yeast reproduces by budding. In this method, the cell undergoes unequal division and produces small buds. The buds separate from mother cell on maturation and start life as new individuals.

spore formation in rhizopus

Spore Formation

Members of the Kingdom Fungi and simple plants; like algae; reproduce by spore formation. Special asexual reproductive structures are formed in these organisms. Zoospores are the most common structure among such asexual reproductive structures. Zoospore is usually a microscopic motile structure. Other common asexual reproductive structures are conidia (Penicillium), buds (Hydra) and gemmules (sponge).

vegetative propagation in potato

Vegetative Propagation

Many higher plants reproduce by this method. When reproduction takes place through vegetative parts rather than reproductive parts in these plants, it is termed as vegetative propagation. In this method, a new plant is produced from roots, leaves or stems. Runner, rhizome, sucker, tuber, offset, bulb, etc. are examples of vegetative structures which produce new offspring. Such structures are called vegetative prpoagules. Examples of vegetative propagules are; eyes of potato, rhizome of ginger, bulbil of agave, leaf buds of bryophyllum, offset of water hyacinth, etc.