Water is very ess

Some features of plants which help them to survive in water scarce environment are:-

a) Formation of tap root which increases the surface area for absorption of water underground.

b) Some modifications like sunken stomata and leaves turn into spine to reduce the loss of water.

c) Reducing water loss by transpiration.

Some features of animals which help them to survive in water scarce environment are:-

a) Use of metabolically produced water.

b) Mucous layer on the surface to reduce water loss by perspiration.

c) Various hormones like ADH help reduce water loss.

OR

Organisms cope with stressful external environmental conditions which are localised or of short duration by following processes:-

a) Regulate:- Some organisms are able to regulate or maintain homeostasis according to the environmental conditions by maintaining constant body temperature or constant osmotic concentration, etc.

e.g. Thermoregulators, Osmoregulators.

b) Conform:- When the body’s internal environment keeps changing according to the ambient conditions.

c) Migrate:- Some organisms move away temporarily from stressful environment o a more hospitable environment and return after the stressful environment is over.

d) Suspend:- Some lower plants , fungi and bacteria form spores to pass the stressful condition. Animals use hibernation, aestivation and diapauses to pass through the stressful condition.