Chapter 11 Solutions — Reproduction — How Life Continues

Revise, Reflect, Refine

1. 1.
   A flower's anthers are removed before it matures. Later, pollen from another plant of the same species is dusted onto its stigma and seeds are produced. Which process has been ensured here?

   • (i) Self-pollination
   • (ii) Cross-pollination
   • (iii) Fertilisation
   • (iv) Tissue culture
2. 2.
   Arrange the following stages of sexual reproduction in plants in the correct order:

   • (i) Pollen germination on stigma
   • (ii) Fertilisation
   • (iii) Pollination
   • (iv) Formation of zygote
3. 3.
   Assertion (A): The zygote formed after fertilisation immediately attaches to the uterus wall. Reason (R): The uterus wall is always prepared to receive the zygote.

   • (i) Both A and R are true, and R is the correct explanation of A.
   • (ii) Both A and R are true, but R is not the correct explanation of A.
   • (iii) A is true, but R is false.
   • (iv) A is false, but R is true.
4. 4.
   Why does asexual reproduction produce offsprings that are genetically identical to the parent?
5. 5.
   Explain why the menstrual cycle stops during pregnancy.
6. 6.
   Why are flowers that bloom at night white or light in colour as compared to flowers that bloom during the day?
7. 7.
   Why do vegetatively propagated plants tend to be more vulnerable to diseases than sexually reproduced plants?
8. 8.
   If all flowers in a type of plant were only capable of self-pollination, how would it affect the genetic diversity over several generations? Explain.
9. 9.
   A farmer wants to produce a large number of genetically identical plants quickly. Suggest suitable reproduction methods and explain why they are effective.
10. 10.
    Suresh prepares slides with pollen grains in different sugar concentrations (0%, 2.5%, 5%, 7.5%, 10%) to study the germination of pollen.

    • (i) What are the different hypotheses which can be tested using this set-up?
    • (ii) What parameters should be kept the same in this set-up?
11. 11.
    Look at the picture given below and think in line with the given prompts and find out which type(s) of pollination might have been followed in these flowers — Tomato: Stamens cover the stigma. Wheat: Flowers open after pollination. Papaya: Male and female flowers are often borne on different papaya trees.
12. 12.
    In the lower Himalayan region of northern India, apples are an important cash crop. The fruit yield is declining due to climate change and decline in natural pollinators. A researcher-farmer group set up two experimental apple orchards at two distinct locations: Place A (natural pollinators allowed) and Place B (mixed farming with beekeeping). The yield is depicted in Fig. 11.24 in terms of…
13. 13.
    A student claims, "In humans, ovulation always happens on day 14 of the menstrual cycle". Critically examine this claim and state whether the claim is correct or not. Give at least two reasons for your answer.