Question

12.1. Explain briefly the disadvantages of asexual reproduction.

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

12.3. a) What is reflex action?
b) Draw a well-labelled diagram of neuron.
c) Describe the central nervous system.

Answer 1

11.1 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) Reflex action is a sudden and involuntary response to stimuli. It helps organisms to quickly adapt to an adverse circumstance that could have the potential to cause bodily harm or even death.

b)
c) The central nervous system primarily consists of the brain and the spinal cord. The system coordinates and controls various aspects of life, ranging from physical attributes (heartbeat, breathing) to mental capabilities (memory, intelligence).