notes of Reproduction of animals plz for 8 class
Answers
Facts the Matter
• The process of reproduction is not essential for the survival of an individual but reproduction is essential for the continuation of a species.
• Modes of Reproduction: Like plants, animal also reproduce by (i) Sexual reproduction and (ii) Asexual reproduction.
Sexual Reproduction: The type of reproduction beginning from the fusion of male and female gametes is known as sexual reproduction. In this process of sexual reproduction, a male and a female gamete (reproductive cells) fuse to form a single cell called Zygote. This zygote gradually develops into an adult, similar to the parents. The individual that grows from a zygote, receives character of both the parents � mother and father.
Asexual Reproduction: The type of reproduction in which only a single parent is involved is called asexual reproduction. In asexual reproduction, sex cells (gametes) are n6t produced. No fusion of gametes takes place for the production of zygote or off springs.
Reproduction in Animals - Class 8 : Notes
Reproduction:
Reproduction is the process by which living organisms produce more living organisms of its own kind.Mode of Reproduction:
There are two main types of reproduction in living organisms.
1. Asexual Reduction: The process of reproduction in which new individuals are produced from a single parent. E.g. microorganisms.
Asexual reproduction is found in the single-celled organism such as the archabacteria, eubacteria etc. Many plants and fungi reproduce asexually as well.
2. Sexual Reproduction: The process of reproduction in which two individuals are involved to produce a new individual. E.g. Human, tigerSexual Reproduction:
In animals, males and females have different reproductive parts or organs. The reproductive parts in animals produce gametes that fuse to form a zygote. 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.
Reproductive Organs in Humans:
1. Male Reproductive Organs:
A pair of testes (singular, testis), two sperm ducts and a penis, these are the male reproductive organs. The testes produce the male gametes called sperms. Millions of male gametes (sperms) are produced by the testes. Though sperms are very small in size, each has a head, a middle piece and a tail. Sperm is a single cell with all the usual cell components.Female Reproductive Organs:
A pair of ovaries, oviducts (Fallopian tubes) and the uterus, these are the female reproductive organs. Ovary produces female gametes called ova (eggs). In human beings, a single matured egg is released by one of the ovaries, into the oviduct every month. Uterus is the part where development of the baby takes place. An egg is also a single cell.Fertilization:
The process of fertilization is fusion of a male gamete (Sperm) with a female gamete (Ovum) is called fertilization. Zygote is formed after fertilization.
Types of Fertilization:There are two types of fertilization in animals, external fertilization and internal fertilization.
1. Internal Fertilisation: When fertilization takes place inside the animal’s body, it is called internal fertilization. Internal fertilization occurs in many animals including humans, cows, dogs and hens.
2. External Fertilisation: In this type of fertilization, the fusion of a male and a female gamete takes place outside the body of the animal’s body is called external fertilization. It is very common in aquatic animals such as fish, starfish, etc.
Example: During spring or rainy season, frogs and toads move to ponds and river. When the male and female come together in water, the female lays the eggs, the male deposits sperms over them. Each sperm swims randomly in water with the help of its long tail. The sperms then come in contact with the eggs.