notes of chapter class 8 reproduction in animals
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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.
• The reproductive parts in humans and the process of reproduction in them. In humans, male and female reproductive parts are present in separate individuals.
Male Reproductive Organs: Male human reproductive organs contain: • A pair of testes (singular-testis), two sperm duct and a penis. • The testes produce the male gametes� called sperms. • The sperm ducts carry sperms to the penis. • The penis is used for ejecting sperms and also passing urine. The tail in sperm helps in movement of the sperm to reach the egg in the female sex organs. • Human Sperm: A sperm is unicellular (single celled), has a head, a middle piece and a tail.
Female Reproductive Organs: Female human reproductive organs contain: • A pair of ovaries which produce , female gametes called ova (eggs). • Oviduct (fallopian tubes): A single natured egg is released into the oviduct by one of the ovaries every month. • Uterus: Uterus is the part where development of the baby takes place. • Egg (ovum): Like a sperm, an egg is also a single cell. It contains a nucleus and the cytoplasm.
The egg may be very small as in humans, much larger as in ducks and hens. Ostrich egg is the largest.
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