Class 10 Science Chapter –  7 How do Organisms Reproduce? Questions and Answers New NCERT Updated Syllabus 

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Class 10 Science Chapter –  7 How do Organisms Reproduce? Questions and Answers

E X E R C I S E S Page no: 127

Question: 1. Asexual reproduction takes place through budding in 

(a) Amoeba. 

(b) Yeast. 

(c) Plasmodium. 

(d) Leishmania. 

Answer: (b) Yeast.

Explanation: Yeast reproduces asexually through a process called budding, where a small bud forms on the parent organism and eventually detaches to grow into a new individual.

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

(a) Ovary 

(b) Uterus

(c) Vas deferens

(d) Fallopian tube 

Answer: (c) Vas deferens.

Explanation: The vas deferens is part of the male reproductive system, responsible for transporting sperm. The female reproductive system includes the ovaries, uterus, and fallopian tubes.

Question: 3. The anther contains 

(a) sepals. 

(b) ovules.

(c) pistil. 

(d) pollen grains. 

Answer: (d) Pollen grains.

Explanation: The anther is the part of the stamen (male reproductive part of a flower) that produces and contains pollen grains, which are the male gametes in flowering plants.

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

Answer: Advantages of Sexual Reproduction: – 

1. Genetic Variation:

– Sexual reproduction involves the combination of genetic material from two parents, leading to offspring with unique genetic combinations. This variation is crucial for the adaptability and survival of species in changing environments.

2. Survival of Species:

– The genetic diversity produced through sexual reproduction increases the chances that some individuals in a population will possess traits that allow them to survive environmental changes, diseases, or other challenges.

3. Evolutionary Potential:

– The introduction of new genetic combinations can lead to evolutionary changes over generations, allowing species to evolve and adapt to new conditions.

4. Elimination of Harmful Mutations:

– Sexual reproduction can help reduce the accumulation of harmful mutations in a population, as these mutations may not be passed on to the next generation if they do not contribute to reproductive success.

5. Enhanced Adaptability:

– Populations that reproduce sexually can adapt more quickly to new challenges, such as climate change or new predators, compared to those that reproduce asexually, which may be more uniform and less adaptable.

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

Answer: Functions of the Testis : – 

  1. Sperm Production:
    • The primary function of the testes is to produce sperm cells (spermatogenesis). This process occurs in the seminiferous tubules within the testes.
  2. Hormone Secretion:
    • The testes secrete male sex hormones, primarily testosterone, which is responsible for the development of male secondary sexual characteristics during puberty, such as increased muscle mass, deepening of the voice, and growth of facial hair.
  3. Temperature Regulation:
    • The testes are located in the scrotum, outside the abdominal cavity, to maintain a temperature slightly lower than the body temperature, which is essential for optimal sperm production and viability.
  4. Storage of Sperm:
    • The testes also play a role in the initial storage of sperm before they are transported through the reproductive tract.

Question: 6. Why does menstruation occur? 

Answer: Reasons for Menstruation:

  1. Preparation for Pregnancy:
    • Menstruation is part of the menstrual cycle, which prepares the uterus for a potential pregnancy. Each month, the lining of the uterus thickens to provide a nourishing environment for a fertilized egg.
  2. Lack of Fertilization:
    • If fertilization does not occur (i.e., if the egg is not fertilized by sperm), the thickened uterine lining is no longer needed. The body signals the breakdown of this lining.
  3. Shedding of the Uterine Lining:
    • The shedding of the uterine lining, along with blood and mucous, occurs through the vagina. This process is known as menstruation and typically lasts for about two to eight days.
  4. Hormonal Regulation:
    • Menstruation is regulated by hormones, including estrogen and progesterone. When hormone levels drop (due to the absence of pregnancy), the uterine lining is expelled.
  5. Cycle Continuation:
    • Menstruation marks the end of one menstrual cycle and the beginning of another, allowing the reproductive system to reset and prepare for the next potential cycle of ovulation and fertilization.

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

Answer: A labelled diagram of a flower’s longitudinal section typically includes the following parts: 

1. Stamen: The male reproductive part, consisting of the anther (produces pollen) and filament.

2. Pistil: The female reproductive part, made up of the ovary (contains ovules), style, and stigma (receives pollen).

3. Petals: Attract pollinators.

4. Sepals: Protect the flower bud.
(Include a diagram with these labels for clarity.)

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

Answer: Contraceptive methods include :– 

  • Mechanical Barriers: Such as condoms, which prevent sperm from reaching the egg.
  • Hormonal Methods: Oral contraceptive pills that regulate hormones to prevent ovulation.
  • Intrauterine Devices (IUDs): Like copper-T, placed in the uterus to prevent fertilization.
  • Surgical Methods: Such as tubal ligation in females or vasectomy in males to block reproductive pathways.

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

Answer: Unicellular Organisms : –

  • Reproduction Method: Primarily reproduce asexually.
  • Common Modes:
    • Fission: This is the most common method where the organism divides into two or more equal parts. For example:
      • Binary Fission: Seen in organisms like Amoeba and Bacteria, where the cell splits into two identical cells.
      • Multiple Fission: In organisms like Plasmodium, the cell divides into many daughter cells simultaneously.
    • Budding: Some unicellular organisms like yeast reproduce by forming small buds that eventually detach and grow into new individuals.

Multicellular Organisms – 

  • Reproduction Method: Can reproduce both asexually and sexually.
  • Common Modes:
    • Asexual Reproduction:
      • Fragmentation: Organisms like Spirogyra can break into fragments, each of which can grow into a new individual.
      • Budding: In organisms like Hydra, buds form on the parent organism and develop into new individuals.
      • Vegetative Propagation: In plants, parts like roots, stems, or leaves can develop into new plants (e.g., sugarcane, roses).
    • Sexual Reproduction: Involves the fusion of male and female gametes, resulting in greater genetic variation. This is common in more complex organisms, including flowering plants and animals (e.g., humans).

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

Answer: Reproduction plays a crucial role in maintaining the stability of populations of species in several ways: –

  • Population Maintenance: Reproduction ensures that new individuals are produced to replace those that die, thus maintaining the population size. This is essential for the survival of a species.
  • Genetic Variation: Through processes like sexual reproduction, genetic variation is introduced within a population. This variation is vital for adaptation to changing environments and helps populations survive in the face of challenges such as diseases or climate changes.
  • Stability in Ecosystems: Stable populations contribute to the overall stability of ecosystems. When species reproduce successfully, they can occupy their ecological niches effectively, which supports the balance of the ecosystem.
  • Response to Environmental Changes: Populations with higher genetic diversity can adapt more readily to environmental changes. For instance, if a population of bacteria is exposed to a new antibiotic, some genetically varied individuals may survive and reproduce, leading to a population that can withstand the antibiotic

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

Answer: Adopting contraceptive methods can be influenced by various factors, including:

  • Family Planning: Couples may wish to control the number and timing of their children to ensure they can provide adequately for each child, both emotionally and financially.
  • Health Considerations: Some individuals may have health conditions that make pregnancy risky for the mother or the child. Contraceptives can help avoid such health complications.
  • Economic Factors: In many cases, families may choose to limit the number of children to improve their economic stability and quality of life. Fewer children can mean more resources available for each child.
  • Educational Goals: Individuals may want to complete their education or establish their careers before starting a family. Contraceptive methods allow them to postpone pregnancy.
  • Social and Cultural Factors: In some societies, there may be cultural or social pressures to limit family size or to space out pregnancies for various reasons, including maternal health.
  • Preventing Sexually Transmitted Infections (STIs): Certain contraceptive methods, such as condoms, also help reduce the risk of STIs, making them a dual-purpose option for many individuals.

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