E X E R C I S E S CHAPTER 7 How do Organisms Reproduce? SCIENCE NCERT TEXTBOOK (CBSE) CLASS 10:

 E X E R C I S E S  

CHAPTER  7  How do Organisms  Reproduce? 


1. Asexual reproduction takes place through budding in:

Answer: (b) Yeast Budding is a form of asexual reproduction where a new organism grows from a bud on the parent organism. Yeast reproduces this way.

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

Answer: (d) Vas deferens The vas deferens is part of the male reproductive system. The female reproductive system includes the ovaries, uterus, and fallopian tubes.

3. The anther contains:

Answer: (c) Pollen grains The anther is part of the male reproductive organ (stamen) in flowers, and it contains the pollen grains, which carry the male gametes (sperm cells).

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

  • Genetic diversity: Sexual reproduction leads to offspring with a combination of genes from both parents, which enhances genetic diversity and adaptability to changing environments.
  • Evolutionary advantages: It allows for more variation, which can help populations evolve and adapt over time.
  • Resilience to diseases: Genetically diverse populations are more resistant to diseases, as not all individuals will have the same genetic weaknesses.

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

The testis has two main functions:

  1. Production of sperm (spermatogenesis) for reproduction.
  2. Secretion of hormones, particularly testosterone, which is responsible for the development of male secondary sexual characteristics and regulation of the male reproductive system.

6. Why does menstruation occur?

Menstruation occurs as a part of the menstrual cycle in females. It is the shedding of the uterine lining (endometrium) when pregnancy has not occurred. This process is controlled by hormonal changes in the body, and it prepares the body for a possible pregnancy in the next cycle.

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

Since I can't draw directly in this format, I can describe the labelled parts of a flower:

  • Stigma: The top part of the pistil where pollen grains land.
  • Style: The tube that connects the stigma to the ovary.
  • Ovary: The part that contains ovules (female gametes).
  • Ovules: Female reproductive cells that develop into seeds when fertilized.
  • Anther: The part of the stamen that produces pollen.
  • Filament: The stalk that supports the anther.
  • Petals: The colorful part of the flower that attracts pollinators.
  • Sepals: The outer protective leaf-like structures.

8. What are the different methods of contraception?

Contraceptive methods include:

  • Barrier methods: Condoms, diaphragms, cervical caps.
  • Hormonal methods: Birth control pills, injections, implants.
  • Intrauterine devices (IUDs): Copper or hormonal devices placed in the uterus.
  • Natural methods: Rhythm method, withdrawal.
  • Sterilization: Surgical methods like vasectomy and tubectomy.
  • Emergency contraception: Morning-after pill.

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

  • Unicellular organisms (like bacteria and amoeba) reproduce mainly through asexual reproduction such as binary fission, budding, or spore formation.
  • Multicellular organisms generally reproduce sexually, involving the fusion of male and female gametes (sperm and egg). Some multicellular organisms also reproduce asexually through methods like fragmentation or vegetative propagation.

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

Reproduction allows species to produce offspring, ensuring the survival of the species over generations. Sexual reproduction increases genetic diversity, which enables populations to adapt to changing environments and resist diseases, providing stability in fluctuating ecosystems.

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

Reasons for using contraceptive methods include:

  • Family planning: To space out children or prevent unwanted pregnancies.
  • Health reasons: To reduce health risks related to pregnancy or childbirth.
  • Economic reasons: To manage family size and resources effectively.
  • Environmental reasons: To control population growth and reduce pressure on resources.
  • Personal choice and empowerment: To give individuals control over their reproductive health.

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