Biology · Organisms and Populations · NEET
No, but they are linked. Evolution is the slow change in a whole population over many generations. An adaptation is the actual useful feature (shape, function or behaviour) that this process produces. So evolution is the process; the adaptation is the result you can see. NCERT says adaptations are the outcome of natural selection over a long evolutionary time, not something an individual chooses in its lifetime.
An adaptation is fixed and inherited (passed to offspring) and takes many generations to appear, like the kangaroo rat's water-saving kidney. Acclimatisation is a short-term adjustment that one organism makes in its own lifetime, like a person's body making more red blood cells within a few days of reaching high altitude. Adaptation is genetic and permanent; acclimatisation is temporary and reversible.
Morphological (body shape and structure): desert plants have thick, waxy leaves and thorns; camels store fat in a hump. Physiological (how the body works inside): the kangaroo rat makes metabolic water and passes concentrated urine; humans at high altitude produce more RBCs. Behavioural (what the organism does): desert lizards bask in the sun when cold and move to shade or burrows when hot to keep body temperature steady.
It uses two physiological adaptations. First, it produces water inside its own body by the breakdown (oxidation) of fat, called metabolic water. Second, its kidneys are so efficient that it concentrates its urine to a great degree, losing very little water. Because of these features it can meet all its water needs without ever drinking, which is a favourite NEET example.
All of these reduce water loss (transpiration) in a dry, hot habitat. A thick cuticle (waxy layer) and reduced leaf surface cut evaporation; sunken stomata trap moist air near the pore so less water escapes; thorns (modified leaves) lower the exposed area and deter herbivores. Some desert plants like Opuntia have no leaves at all and photosynthesise through flattened green stems, and they use the special CAM pathway to open stomata at night.
Behaviour is a full third category of adaptation. A desert lizard cannot make its own heat, so it basks in sunlight to warm up and moves into a burrow or shade when it gets too hot, keeping its body temperature fairly steady. This purposeful behaviour to survive abiotic stress counts as a behavioural adaptation in NCERT.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Adaptation is any attribute of an organism (morphological, physiological or behavioural) that enables the organism to survive and reproduce in its habitat. It is the outcome of natural selection over evolutionary time.
It is a physiological adaptation: the kangaroo rat produces metabolic water by internally oxidising fat and passes highly concentrated urine, so it loses almost no water and does not need to drink.
The hump itself is a morphological (structural) feature that stores fat. When that stored fat is broken down to release energy and metabolic water, that internal process is physiological. NEET may test either angle, so link the structure to its function.
CAM (Crassulacean Acid Metabolism) is a pathway in many desert plants where stomata open at night, not in the hot day, to take in CO2 while losing far less water. It is a physiological adaptation to a dry habitat.
No. Morphological adaptations are visible (thorns, thick leaves, streamlined body), but physiological ones (concentrated urine, metabolic water, more RBCs) and behavioural ones (basking, burrowing, migration) may not be seen directly. All three are equally valid adaptations.
