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NCERT Book – Exercise and Solutions

Question: 1. Asexual reproduction takes place through budding in

  1. Amoeba
  2. Yeast
  3. Plasmodium
  4. Leishmania

Answer: (b) Yeast

Question: 2. Which of the following is not a part of the female reproductive system in human beings?

  1. Ovary
  2. Uterus
  3. Vas deferens
  4. Fallopian tube

Answer: (c) Vas deferens

Question: 3. The anther contains

  1. Sepals
  2. Ovules
  3. Carpel
  4. Pollen grains

Answer: (d) Pollen grains

Question: 4. What are the advantages of sexual reproduction over asexual reproduction?

Answer: Sexual reproduction facilitates variations at a faster pace. Thus, evolution of new and complex species could have been possible because of sexual reproduction.

Question: 5. What are the functions performed by the testis in human beings?

Answer: Functions of Testis:

  1. Production of sperms.
  2. Production of the hormone testosterone.

Question: 6. Why does menstruation occur?

Answer: In each ovulation cycle, an egg is released from the ovary which is transferred to the fallopian tube. Additionally, the uterus prepares itself for a possible pregnancy. The lining of uterus thickens. When no conception happens, the lining of the uterus is shed in fragments; along with the unfertilized egg. These things are released out through the vagina in the form of bleeding; called menstruation.

Question:7. Draw a labelled diagram of the longitudinal section of a flower.



Question: 8. What are the different methods of contraception?

Answer: There are various methods of contraception. The physical barrier methods prevent the entry of sperm into the uterus. The hormonal pills prevent transfer of egg to the uterus. Copper-T is a method which prevents entry of sperms in the fallopian tube and thus prevents fertilization. Surgical methods are permanent methods to stop the chances of pregnancy.

Question: 9. How are the modes for reproduction different in unicellular and multicellular organisms?

Answer: Unicellular organisms always reproduce by asexual methods; like binary fission, budding, multiple fission, etc. Multicellular organisms, on the other hand, use both asexual and sexual methods for reproduction. While simple organisms usually follow the asexual methods of reproduction; most of the multicellular organisms follow sexual methods of reproduction.

Question: 10. How does reproduction help in providing stability to populations of species?

Answer: Every species has to constantly struggle for its survival. Natural predators and vagaries of nature keep on removing a large section of the population of a particular species. Moreover, the natural cycle of life and death also removes a section of the population. Reproduction is a way to replenish the lost section of population. Thus, it can be said that reproduction is linked to the stability of population of a species.

Question: 11. What could be the reasons for adopting contraceptive methods?

Answer: There are two main reasons for adopting contraceptive methods. One of them is limiting the number of children a couple wants to have. Another goal is to maintain adequate gap between two consecutive children. Some contraceptive methods also help in preventing STDs.