The embryo gets embedded in the walls of uterus. In the uterus, the embryo grows and develops all the body parts.
Asexual reproduction is a type of reproduction in which only one parent is involved and the offspring is genetically identical to the parent cell.
Two methods of asexual reproduction are budding and binary fission.
Metamorphosis is a biological process of transformation of an immature form, such as larva, into an adult through drastic changes. It is observed in frogs (transformation of tadpole into adult frog) and in insects (transformation of larva into moths or butterflies).
Differences between a zygote and a foetus are:
Zygote |
Foetus |
It is unicellular. Hence, no well-defined body parts. |
It is multicellular and has well-defined body parts. |
It forms due to the fertilisation of sperm and ovum. |
It forms after the process of fertilisation in which zygote multiplies and grows into a multicellular body. |
Fusion of a sperm and an ovum is called fertilisation. In human beings, the process of fertilisation takes place in the oviducts. The sperms produced by testes in male’s body are transferred into the female body. In female’s body, one matured ovum is released into the oviduct by one of the ovaries every month. In the oviduct, the sperm comes in contact with the ovum and fuses with it. During the process of fusion, the nuclei of the sperm and the ovum fuse to form one single nucleus. This results in the formation of zygote.
Characters |
Internal Fertilisation |
External Fertilisation |
Site of fertilisation |
Inside female body |
Outside female body |
Number of eggs/offspring produced |
Less |
Large |
Chances of survival of eggs/offspring |
High |
Low |
Example |
Mostly mammals |
Generally fish and frog |
(a) (i) in female body.
(b) (ii) metamorphosis
(c) (ii) one
Importance of reproduction in organisms is:
(a) Oviparous animals give birth to young ones. (F)
(b) Each sperm is a single cell. (T)
(c) External fertilisation takes place in frog. (T)
(d) A new human individual develops from a cell called gamete. (F)
(e) Egg laid after fertilisation is made up of a single cell. (T)
(f) Amoeba reproduces by budding. (F)
(g) Fertilisation is necessary even in asexual reproduction. (F)
(h) Binary fission is a method of asexual reproduction. (T)
(i) A zygote is formed as a result of fertilisation. (T)
(j) An embryo is made up of a single cell. (F)
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