Question

Which of the following statement(s) regarding the response to abiotic factors is/are incorrect?

(i) Plants are not capable of thermoregulation.
(ii) Almost all plants and 99% of animals are conformers.
(iii) Heat loss or heat gain is a function of the surface area of the body
(iv) Thermoregulation is the least energy consuming process in small animals
(v) 99% of animals are thermoregulators
(vi) Archaebacteria cannot tolerate high temperatures.

• A. i, ii and iii
• B. iv, v and vi
• C. ii and iv
• D. i, ii, vi

Answer 1

The correct option is B iv, v and vi

Organisms living in a particular environment are impacted to a greater extent whenever there is a change in the environment.

Some organisms respond to the changes happening in their external environment by maintaining a steady state internally.

Many organisms however prefer changing their internal environment to conform to the changes in the external environment.

Based on whether organisms can maintain a constant internal environment, they can be classified as conformers and regulators.

Conformers are organisms that cannot maintain a constant internal environment.

With respect to temperature, the body temperature of these organisms changes with the ambient temperature.

99% of animals and nearly all plants are conformers.

Hence, statements i and ii are correct and statement v is incorrect.

On the other hand, organisms such as birds and mammals are considered regulators which maintain a constant internal environment (homeostasis) at all times irrespective of the changes in the external environment.

This stability is in terms of a constant body temperature, osmotic concentration of body fluids, etc.

However, in small animals, maintaining a constant temperature requires a lot of energy. This is because they have a large surface area compared to their volume and loss or gain of heat is a function of the surface area of an organism. Larger surface area implies that more area of the organism's body is exposed to the surroundings, leading to more heat loss. Thus, these organisms tend to lose heat very fast when it is cold outside. It requires a lot of energy to generate the lost body heat.

Hence, statement iii is correct but statement iv is incorrect.

Archaebacteria are a group of unique prokaryotic organisms which are known as extremophiles as they are capable of surviving in extreme environmental conditions.

The archaebacteria which live in hot springs are termed as thermoacidophiles and they are capable of tolerating high temperatures (as high as 100 degrees Celsius).

Hence, statement vi is incorrect.