Read the given paragraph and answer the given question.
Nearly all plants cannot maintain a constant internal environment. Their body temperature changes with the ambient temperature. In aquatic animals, the osmotic concentration of the body fluids change with that of the ambient water osmotic concentration. These animals and plants are simply conformers. Considering the benefits of a constant internal environment to the organism, we must ask why these conformers had not evolved to become regulators. Recall the human analogy we used above; much as they like, how many people can really afford an air conditioner ? Many simply 'sweat it out' and resign themselves to suboptimal performance in hot summer months. Very small animals are rarely found in polar regions. During the course of evolution, the costs and benefits of maintaining a constant internal environment are taken into consideration. Some species have evolved the ability to regulate, but only over a limited range of environmental conditions, beyond which they simply conform.If the stressful external conditions are localised or remain only for a short duration, the organism has other alternatives for survival.
Conformers are the animals whose:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Body temperature changes with the ambient temperature.
Option (1) Body temperature remains constant. — Incorrect. A constant body temperature is the mark of a regulator.
Option (2) Body temperature is higher than the ambient temperature. — Incorrect. Conformers do not keep their body warmer than the surroundings.
Option (3) Body temperature is lower than the ambient temperature. — Incorrect. Conformers do not keep their body cooler than the surroundings.
Option (4) Body temperature changes with the ambient temperature. — Correct. This is what makes an animal a conformer: it cannot keep its internal conditions steady, so its body temperature changes with the ambient temperature. Regulators, such as birds and mammals, keep a constant body temperature instead.
Note 1: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
Note 2: This question is from the topic “Responses to Abiotic Factors” in Chapter 13, Organisms and Populations, of the pre-rationalised NCERT book. This portion is not in the present NCERT book, where the chapter is now Chapter 11, Organisms and Populations. The extract below is from the pre-rationalised edition.
NCERT Extract (Pre-rationalised edition, Chapter 13, Organisms and Populations):
Responses to Abiotic Factors – “… An overwhelming majority (99 per cent) of animals and nearly all plants cannot maintain a constant internal environment. Their body temperature changes with the ambient temperature. In aquatic animals, the osmotic concentration of the body fluids change with that of the ambient air, water osmotic concentration. These animals and plants are simply conformers.”