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Reproduction in animals





Reproduction in humans:

Fertilization in human is internal.,
Puberty:
The onset of sexual maturity occurs in boys at the age of 11-16 years, and in girls at the age of 10-15 years. This is known as puberty.

The Male reproductive system:

  • The male gametes or sperm are produced in a pair of testes. They are situated outside the abdominal cavity in the scrotal sac.
  • Each sperm is a single cell with the entire usual cell component. Each sperm has a head, a middle piece and a tail.
  • The sperm is carried by a pair of sperm ducts, called vas deferens, to the urethra present in penis.
  • Penis is the organ that transfers the sperms into the female reproductive tract.
  • Sex glands pour a mixture of fluids into the sperm duct that keeps the sperms alive. The sperm and the fluid together form the semen.

Female reproductive system:

  • The female reproductive organs are a pair of ovaries, the oviduct (fallopian tubes) and the uterus.
  • These are located in the lower part of the abdomen.
  • The ovaries produce the egg or ovum when a female reaches puberty.


Fertilization:

  • Male gametes are introduced into the female reproductive tract by the penis. Both the gametes meet in the oviduct. The fusion between a male gamete and a female gamete in the oviduct result in the formation of a fertilized egg or zygote.
  • Fertilization and development of the zygote to form a new individual takes place inside the body of the female.

Development of the fetus:

  • After fertilization, the zygote passes into the uterus, or womb. It divides again and again to form the embryo. The embryo becomes embedded in the lining of the wall of the uterus. This is called implantation.
  • At two months, the embryo starts resembling the human form is called the foetus. It takes nine months for the embryo to grow and develop into a fully-formed baby. This period is called gestation period.
  • The foetus is attached to the uterus by a special structure called the placenta. The placenta is responsible for providing oxygen and nutrients and removing waste substances.

In Vitro fertilization (IVF):

  • It is a method in which ovum collected from a female’s body is allowed to fuse with sperm collected from a male’s body in an external medium or outside the body of the female.
  • The zygote so developed is allowed to grow in vitro (i.e.in glass) for about a week and then implanted in the female’s uterus where it further develops as a normal embryo.
  • A baby born of this technique is often called a ‘test tube’ baby.



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Class 8 Maths Class 8 Science
Reference Books for class 8 science

Given below are the links of some of the reference books for class 8 science.

  1. Oswaal NCERT & CBSE Pullout Worksheets Class 8 Science These worksheets can help student evaluate whatever he/she has studied from the text books.
  2. Science for Class 8 Paperback by Lakhmir Singh Detailed science book to clear basics and concepts. I would say it is a must have book for class 8 student.
  3. Pearson Foundation Series (IIT -JEE / NEET) Physics, Chemistry, Maths & Biology for Class 8 (Main Books) | PCMB Combo : These set of books could help your child if he aims to get extra knowledge of science and maths. These would be helpful if child wants to prepare for competitive exams like JEE/NEET. Only buy if you can provide help to the child while studying.
  4. Reasoning Olympiad Workbook - Class 8 :- Reasoning helps sharpen the mind of child. I would recommend students practicing reasoning even though they are not appearing for Olympiad.

You can use above books for extra knowledge and practicing different questions.







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