(i) Regulate : Maintain constant internal temperature / osmotic concentration /homeostasis.

e.g. birds / mammals.

(ii) Conform : Do not maintain constant internal temperature / osmotic concentration / No homeostasis.

e.g. any one example of animal other than birds and mammals.

(iii) Migrate : Temporary movement of organisms from the stressful of habitats to hospitable areas and return when stressful period is over.

e.g. birds from Siberia / or any other correct example.

(iv) Suspend : Reducing / minimising the metabolic activities during unfavourable conditions.

e.g. Polar bear / amphibian / snails / fish / any other example of animals.

Detailed Answer :

(i) Regulate : Certain animals have the ability to maintain a constant temperature and constant osmolality to keep up their homeostasis. For example, mammals have a constant body temperature (37˚C) irrespective of the outside temperature. In summers, to maintain the temperature, they sweat and in winters they shiver to produce heat.

(ii) Conform : About 99% of animals and nearly all plants cannot maintain a constant internal environment. Their body temperature or osmotic concentration change with the surrounding conditions. They are called conformers. Hence, the internal environment of conformers changes with external environment. For example, in aquatic animals, osmotic concentration of body fluids changes with that of the ambient osmotic concentration.

(iii) Migrate : It is the temporarily movement from a stressful habitat to a more hospitable area and return when stressful condition is over. For example, during winter, Keolado National Park (Bhartpur, Rajasthan) hosts migratory birds coming from Siberia and other extremely cold northern regions.

(iv) Suspend : In bacteria, fungi and lower plants, thick walled spores are formed which help them to overcome stressful, unfavourable conditions. Spores germinate when conditions are favourable.