Reproduction in animals

Long Answer Questions for class 8

Question 1. What is puberty? What is it caused by? What changes occur in boys and girl during puberty?
Answer. 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. Puberty occurs in boys at the age of 11-16 years and in girls at the age of voice 10-15 years.
In boys puberty is marked by the voice become deeper, growth of hair on the face and body, and production of sperm by the testes. In girls, breasts become bigger and hips get more rounded.
Question 2. Why do frogs produce a large number of gametes?
Answer. Frogs produce large number of gametes because there are always chances of getting eaten by fish present in the water or getting washed out by wind currents and rainfall. As such, not all gametes are involved in fertilization.
Question 3. Differentiate between oviparous and viviparous animals?

Oviparous animals Viviparous animals
Animals that lay eggs are known as oviparous animals. Animals that give birth to young ones are known as viviparous animals.
In these animals, the development of embryo takes place in the egg after it is laid. In these animals, the development of the embryo takes place inside the body of the mother.
Birds, lizards, crocodiles are some examples of oviparous animals. Human, tiger, goats and cats are some examples of viviparous animals.

Question 4. Describe fertilization in hen?
Answer. Hen exhibit internal fertilization. The zygote is formed following fertilization, divides repeatedly, and rolls down the oviduct. It gets surrounded by many protective sheath or layers including the hard outermost shell. After the hard shell is formed around the embryo, the hen lays egg. The hen then sits on the egg to keep it warm. Development of the chick takes place inside the shell. It takes about 3 weeks for the embryo to develop in to a chick. After its development is complete, the chick comes out by bursting open the egg shell.

Question 5. Discuss how zygote develops in to an individual in humans?
Answer. 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.

Practice questions:

  1. Define reproduction?
  2. What is metamorphosis?
  3. How does fertilization occur in frogs?
  4. How and where does fertilization take place in human beings?
  5. Where are sperm produced in human beings?
  6. List the various stages in life cycle of mosquito?
  7. Where does the embryo get implanted in human?
  8. Discuss how zygote develops in to an individual in humans?
  9. Name the two types of gametes?
  10. What is hermaphrodite? Give an example?
  11. What is implantation?
  12. What is binary fission?
  13. Describe male reproductive system in humans?
  14. Differentiate between the following:
    I. Sexual and asexual reproduction
    II. Embryo and foetus
    III. Egg and sperm
  15. Draw the following:
    I. Human sperm
    II. Male and female reproductive system

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