Q.(a) Distinguish between hibernation and aestivation.

An adaptation is any morphological, physiological or behavioural attribute of an organism that lets it survive and reproduce in its habitat despite variation and stress in the abiotic environment. Organisms cope with such stress in four broad ways. They may regulate, using physiological and behavioural mechanisms to hold their internal environment fairly constant (homeostasis) regardless of external conditions -- all birds and mammals can do this, via thermoregulation and osmoregulation. They may instead simply conform, letting their internal state (body temperature, or in aquatic animals the osmotic concentration of body fluids) track the surrounding environment. They may migrate, moving temporarily to a more hospitable area and returning once conditions improve, as many birds do each winter. Or they may suspend activity altogether, reducing their metabolism and entering a dormant state -- seed dormancy in plants, hibernation through winter (e.g., the polar bear) or aestivation through summer heat (e.g., certain snails and fish) in animals. Concrete examples of morphological/physiological adaptation include thick leaf cuticles and sunken stomata plus C …