Which of the following statement regarding the response of living organisms to external stimuli is correct ?

Options

A. The external environmental stimuli can be physical, chemical or biological.
B. All organisms, from the prokaryotes to the most complex eukaryotes can sense and respond to environmental stimuli.
C. Consciousness and response to external stimuli is the defining property of living organisms.
D. All of these

Answer

D

Explanation

All organisms, from primitive prokayotes to most advanced and complex eukaryotes, are able to sense and respond to environmental factors. The stimuli are perceived by sense organs in higher animals through sensory receptors e.g., eyes, ears, nose. Plants do not possess such sense organs. However, they do respond to external factors such as light, water, temperature, pollutants, other organisms, etc. Human beings have an additional facility of self consciousness (awareness of self). Consciousness and response to stimuli are said to be the defining properties of living organisms.