Question

12.1. Explain briefly the disadvantages of asexual reproduction.

12.2. Define pollination. What are the two types of pollination?

12.3. a) Write the characteristics of wind-pollinated flowers.
b) What is the function of the ovary?
c) What are the primary and accessory sex organs in males?

Answer 1

12.1 The major disadvantages of asexual reproduction are:

• Lack of diversity- Since the offsprings are genetically identical to the parent they are more susceptible to the same diseases and nutrient deficiencies as the parent. All the negative mutations persist for generations.
• Since only one organism is involved, the diversity among the organisms is limited.
• They are unable to adapt to the changing environment. A single change in the environment may eliminate the entire species.

12.2. The transfer of the pollen grains from the anther to the stigma of a flower is called pollination. The two types of pollination are:

• Self-pollination- Pollination that occurs between the anther and stigma of the same flower or of different flowers present on the same plant.
• Cross-pollination- Pollination that occurs between anther of one flower and stigma of another flower present on different plants of the same kind.

12.3 a) Characteristics of wind-pollinated flowers:

• Wind-pollinated flowers are not showing and do not produce nectar too.
• Instead, they produce larger quantities of light, dry pollen from small, plain flowers that can be carried by the wind.
• Female structures on wind pollinated plants are adapted to capture the passing pollen from the air.

b) Female ovaries have two functions:

• They secrete female sex hormones like the estrogen and progesterone.
• They produce and release of the egg or ovum, female gamete.

c) Primary sex organs in males are testes. The accessory sex organs include the prostate gland, seminal vesicles, urethra and penis.