Class 10 Biology - How do Organisms Reproduce? - Exercises

Multiple Choice Questions

1. Asexual reproduction takes place through budding in: (a) Amoeba. (b) Yeast. (c) Plasmodium. (d) Leishmania. Answer: (b) Yeast.

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 (It is part of the male reproductive system).

3. The anther contains: (a) sepals. (b) ovules. (c) pistil. (d) pollen grains. Answer: (d) pollen grains.

---

Short and Long Answer Questions

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

• Genetic Variation: Sexual reproduction combines DNA from two different individuals, leading to greater variation in the offspring.
• Evolution: This variation is the basis for evolution and allows species to adapt to changing environmental conditions.
• Survival: Increased variation improves the chances of survival of a species over time, especially during drastic environmental shifts.

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

• Production of Sperms: The primary function is to produce male germ-cells (sperms).
• Hormone Secretion: Testes secrete the hormone testosterone, which regulates sperm formation and brings about secondary sexual characteristics in boys during puberty (like facial hair and voice changes).

6. Why does menstruation occur? Answer: Every month, the ovary releases one egg, and the uterus prepares its lining (becoming thick and spongy) to receive a fertilized egg. If the egg is not fertilized, the lining is no longer needed. It slowly breaks down and is discharged through the vagina along with blood and mucous. This monthly cycle is known as menstruation.

7. Draw a labelled diagram of the longitudinal section of a flower. Answer: (Description of the diagram) A longitudinal section of a typical flower shows:

• Sepals: Green outer parts that protect the bud.
• Petals: Colored parts that attract pollinators.
• Stamen (Male Part): Consists of the anther (produces pollen) and the filament.
• Pistil/Carpel (Female Part): Located in the center, consisting of the stigma (sticky top for pollen), style (tube), and ovary (contains ovules).

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

• Mechanical Barriers: Use of condoms or diaphragms to prevent sperm from reaching the egg.
• Hormonal Methods: Oral pills that change the body's hormonal balance to prevent egg release.
• Intrauterine Devices (IUDs): Devices like the loop or Copper-T placed in the uterus to prevent pregnancy.
• Surgical Methods: Vasectomy (blocking vas deferens in males) or Tubectomy (blocking fallopian tubes in females) to permanently prevent fertilization.

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

• Unicellular Organisms: Reproduction is usually simple and involves cell division (fission). A single cell divides to form new individuals.
• Multicellular Organisms: Because of complex body designs and specialized tissues, they use more advanced methods like fragmentation, budding, vegetative propagation, or specialized sexual reproduction involving germ-cells (gametes).

10. How does reproduction help in providing stability to populations of species? Answer: Reproduction ensures the continuity of a species by replacing individuals that die due to age, disease, or predation. The consistency of DNA copying maintains body design features suitable for a particular niche, while inherent variations allow for adaptation to environmental changes, ensuring the population's long-term stability.

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

• To prevent unwanted pregnancies.
• To maintain a healthy gap between children.
• To control the growth of the human population.
• To protect against sexually transmitted diseases (STDs) like HIV-AIDS, gonorrhea, and syphilis (specifically using barrier methods like condoms).
• To safeguard the physical and mental health of the woman.