NCERT Gist: Reproduction in Animals | Additional Study Material for UPSC PDF Download

Just as in plants, there are two modes by which animals reproduce.
These are:
(i) Sexual reproduction.
(ii) Asexual reproduction.

Sexual Reproduction

- Like plants, the reproductive parts in animals also produce gametes that fuse to form a zygote.
- The fusion of ovum and sperm is called fertilization.
- The fertilized egg is called a zygote.
- Fertilization that takes place inside the female body is called internal fertilization. This is observed in human beings and other animals such as hens, cows and dogs.
- Fertilization that takes place outside the female body is called external fertilization. This is observed in frogs, fish, starfish, etc. It is the zygote which develops into a new individual. This type of reproduction beginning from the fusion of male and female gametes is called sexual reproduction.
- The animals which give birth to young ones are called viviparous animals.
- Those animals which lay eggs are called oviparous animals.
- The transformation of the larva into an adult through drastic changes is called metamorphosis.
- Animals such as human beings, cows and dogs which give birth to young ones are called viviparous animals.
- Animals such as hen, frog, lizard and butterfly which lay eggs are called oviparous animals.
- The transformation of the larva into adult through drastic changes is called metamorphosis.
- The type of reproduction in which only a single parent is involved is called asexual reproduction. In hydra, new individuals develop from buds. This method of asexual reproduction is called budding.
- Amoeba reproduces by dividing itself into two. This type of asexual reproduction is called binary fission.
- Asexual Reproduction- In each hydra, there may be one or more bulges. These bulges are the developing new individuals and they are called buds. Recall the presence of buds in yeast.
- In hydra too the new individuals develop as outgrowths from a single parent. This type of reproduction in which only a single parent is involved is called asexual reproduction.
- Since new individuals develop from the buds in hydra, this type of asexual reproduction is called budding.
- Another method of asexual reproduction is observed in the microscopic organism, amoeba. Let us see how this happens.
- Two amoebae are produced from one parent amoeba.
- Asexual reproduction in which an animal reproduces by dividing into two individuals is called binary fission.