Question

Match column I with column II and find out the correct option.

Column 1	Column 2
A) Regulate	i) Thick walled spores of bacteria
B) Conform	ii) Birds and mammals
C) Migrate	iii) Plants
D) Suspend	iv) Siberian crane

• A. A - ii, B - iii, C - iv, D - i
• B. A - i, B - ii, C - iii, D - iv
• C. A - iv, B - i, C - ii, D - iii
• D. A - iv, B - iii, C - ii, D - i

Answer 1

The correct option is A A - ii, B - iii, C - iv, D - i

Organisms respond to their external environment in different ways. On the basis of this response, whether an organism can maintain a constant internal environment (homeostasis) or not, they can be classified as two types:

• Regulators are organisms that can maintain homeostasis, e.g., mammals and birds. These organisms maintain a constant body temperature at all times by using the energy generated by metabolism.
• Organisms that cannot maintain homeostasis are called conformers, e.g., plants and amphibians. Plants cannot generate sufficient energy to maintain a constant temperature. Therefore, they conform to the changes in their external environment.

If the unfavourable conditions in the environment are localised or temporary, then animals can opt for alternative ways to respond to the changes in their environment. They are as follows :

• Some organisms move away from their locality temporarily, in order to escape from adverse climatic conditions, in search of food, shelter and for reproduction. This is called migration. The best example is the Siberian crane which migrates to India during the winter season when it is extremely cold in Siberia.

Figure : Migrating Siberian crane

• Suspend means to stop growth for a period of time, when the conditions are unfavourable and growth resumes when the conditions become favourable. Some organisms like bacteria and fungi form thick walled spores to tide over unfavourable conditions. These spores germinate when suitable conditions are available. Therefore, production of spores suspends their growth for a brief period of time.

Figure : Bacterial spores