Biology, asked by Anonymous, 9 months ago

when a hen reproduces, zygote is formed through which ------------ fertilisation, does not happen in frogs and fish

Answers

Answered by shobi35
3

Explanation:

the answer is internal fertilisation.

Answered by Anonymous
4

Answer:

Objective

This topic gives an overview of;

Sexual Reproduction

Male Reproductive Organs

Female Reproductive Organs

Fertilization

Development of Embryo

Reproduction in Animals

Recall the processes of digestion, circulation and respiration. These processes are essential for the survival of every individual. You have also learnt about the process of reproduction in plants. Reproduction is essential for the continuation of a species. Imagine what would have happened if organisms had not reproduced. You will realise that reproduction is very important as it ensures the continuation of similar kinds of individuals, generation after generation.

Modes of Reproduction

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

Sexual Reproduction

Recall reproduction in plants. Plants that reproduce sexually have male and female reproductive parts. In animals also, males and females have different reproductive parts or organs. Like plants, the reproductive parts in animals also 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. Let us find out the reproductive parts in humans and study the process of reproduction in them.

Male Reproductive Organs

The male reproductive organs include a pair of testes (singular, testis), two sperm ducts and a penis. The testes produce the male gametes called sperms. Millions of sperms are produced by the testes, the below which shows the picture of a sperm. Though sperms are very small in size, each has a head, a middle piece and a tail. Indeed, each sperm is a single cell with all the usual cell components.

Female Reproductive Organs

The female reproductive organs are a pair of ovaries, oviducts (fallopian tubes) and the uterus. Ovary produces female gametes called ova (eggs) In human beings, a single matured egg is released into the oviduct by one of the ovaries every month. Uterus is the part where development of the baby takes place. Like the sperm, an egg is also a single cell.

Fertilization

The first step in the process of reproduction is the fusion of a sperm and an ovum. When sperms come in contact with an egg, one of the sperms may fuse with the egg. Such fusion of the egg and the sperm is called fertilization. During fertilization, the nuclei of the sperm and the egg fuse to form a single nucleus. This results in the formation of a fertilized egg or zygote.The zygote is the beginning of a new individual.

The process of fertilization is the meeting of an egg cell from the mother and a sperm cell from the father. So, the new individual inherits some characteristics from the mother and some from the father. Look at your brother or sister. See if you can recognise some characters in them similar to those of your mother or your father.

Explanation:

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