This PSEB 8th Class Science Notes Chapter 9 Reproduction in Animals will help you in revision during exams.
PSEB 8th Class Science Notes Chapter 9 Reproduction in Animals
→ Reproduction ensures the continuation of similar kinds of individuals, generation after generation.
→ All living organisms reproduce to create more of their own kind. This process is called reproduction.
→ There are two main methods of reproduction.
- Asexual reproduction
- Sexual reproduction
→ In asexual reproduction, a new individual is formed from a single parent.
→ Living organisms reproduce asexually by the following five methods:
- Binary fission
- Spore formation.
- Vegetative reproduction
→ In sexual reproduction, two parents are needed to produce new individuals.
→ The male parent produces male gametes and the female parent produces female gametes.
→ The union of male and female gametes is known as fertilization.
→ There are some organisms in which both the gametes exist in the same individual. Such organisms are called hermaphrodites.
→ The fertilization in some animals is internal and in others external.
→ The process of forming specific shapes and patterns and increasing in size is called development and growth.
→ The growth of parts involves changes in shape, size, and number of constituents.
→ In plants the growth is indefinite but in animals it is definite.
→ The process of formation of the individual from seed, zygote, or body part is called development.
→ There are different ways for the development of individuals.
→ Sexual reproduction is highly evolved.
→ Male Reproductive System consists of a pair of testes, two epididymis, two vasa differentia, accessory glands, two ejaculatory ducts, urethra, and a copulatory organ or penis. Except for testes, all others are secondary male sex organs.
→ The female Reproductive System is made up of a pair of ovaries, a pair of oviducts, uterus, vagina, external genitalia, accessory genital glands, and mammary glands. Except for the first, all others are secondary female sex organs.
→ Semen is a milky fluid produced by the male reproductive system and ejaculated during orgasm.
→ It contains spermatozoa and secretions of glands (seminal vesicles, prostate gland, and Cowper’s glands).
→ The penis is the male copulatory organ that also takes part in the conduction of urine from the body.
→ Spermatazoan (Sperm) is a motile, microscopic male gamete.
→ A typical spermatozoan consists of 4 parts – head, neck, middle piece, and tail.
→ Cloning is the production of an identical cell, carries another living part of a complete organism.
→ The cloned animals are found to be born with severe abnormalities.
→ Sexual Reproduction: A kind of reproduction in which the union of two opposite sexes (male and female) accomplishes fertilization is called sexual reproduction.
→ Asexual Reproduction: A kind of reproduction in which new ones are produced from a single parent is called asexual reproduction.
→ Egg: It is a female gamete produced by the ovary of a female.
→ Sperms: These are male gametes that are produced by the testes of males.
→ Fertilization: The union of male gamete (sperm) and female gamete (egg or ovum) is called fertilization.
→ Zygote: A single-celled structure formed by the union of sperm and egg is called a zygote.
→ Internal Fertilization: Fertilization that takes place inside the body of a female body is known as internal fertilization.
→ External Fertilization: Fertilization that takes place outside the body of females is called external fertilization.
→ Embryo: The zygote divides repeatedly into a structure called an embryo.
→ Foetus: The stage of development of an embryo in which all the body parts are identifiable is called foetus.
→ Viviparous Animals: The animals which produce young ones are known as viviparous animals.
→ Oviparous Animals: The egg-laying animals are known as oviparous animals.
→ Metamorphosis: The drastic change which transforms a larva into an adult is called metamorphosis.
→ Budding: The kind of asexual reproduction in which a new individual develops from the buds is called budding.
→ Binary Fission: A kind of asexual reproduction in which two individuals are produced simply by dividing itself is called binary fission.
→ Cloning: Cloning is the production of an exact copy of a cell or a complete organism.