Question

summary of ch 9 reproduction in animals class 8​

Answer 1

Explanation:

Introduction to Reproduction

Reproduction is the process of giving rise to an offspring.

Reproduction is essential for the continuation of a species.

There are two modes of reproduction:

Sexual reproduction

Asexual reproduction

Asexual reproduction

The type of reproduction in which only a single parent is involved is called asexual reproduction.

There is no mixing of genetic information.

Eg: buds in Hydra

Sexual reproduction

The type of reproduction, which involves two parents to give rise to an offspring is called

sexual reproduction.

The males and females have different reproductive parts or organs.

These organs produce the male and female gametes, which fuse together to form the offspring.

Genetic information from both parents is inherited.

 Eg: humans

To know more about “Modes of Reproduction”, visit here.

Fission

It is a type of asexual reproduction in which a single-celled organism divides into two.

Division of nucleus is followed by division of other cell organelles in the cytoplasm and finally the cytoplasm.

Thus, two cells are produced from one parent cell.

Example: Amoeba.

Amoeba reproduces by binary fission, which is dividing into two cells.

If one parent cell gives rise to many daughter cells, this type of fission is called multiple fission.

To know more about Binary Fission, visit here.

Budding

A bud starts as an outgrowth on the parent body.

As this bud grows, it becomes a new individual organism.

In some organisms, the buds remain attached to the parent’s body (example: yeast)

In some organisms, it detaches from the parent body and develops into a complete mature individual (hydra).

This type of reproduction is called budding.

Answer 2

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We know that all living organisms live for a certain period of time and then die. This reduces the number of individuals of a community. The reduced number is restored by the addition of new individuals through reproduction. The production of new individuals by their parents is known as reproduction. Reproduction is one of the most important characteristics of living organisms. Reproduction is essential for the survival of a species on the earth. It ensures the continuity of life on the earth. In this chapter, we shall learn how reproduction takes place in animals.

MODES OF REPRODUCTION

There are two modes of reproduction in animals.

Sexual reproduction: The production of a new animal by the existing two parents, by the fusion of their gametes, is called sexual reproduction. It involves the fusion of a male gamete with a female gamete which leads to the formation of a zygote, that develops into a new individual. Fishes, frogs, cows, dogs, horses, human beings, etc., reproduce by sexual reproduction.

Asexual reproduction: The production of new animals by a single parent without the involvement of gametes is called asexual reproduction. Since fusion of gametes is not involved, zygotes are not formed in asexual reproduction. The young ones produced are the exact copy of their parents. Amoeba, Hydra, yeast, etc., reproduce by asexual reproduction.

$\huge\dag\sf\red{By \: Divyanshu}$