Answer:
All three options are correct;
1. Both plants and animals have physiological cycles called circadian rhythms.
2. The molecular processes determining how plants and animals perceive environmental changes are equally complex.
3. The molecular processes determining how plants and animals perceive environmental changes are often homologous.
Step-by-step explanation:
Stimulus in biology can be defined as an obvious change in either the chemical or physical structure of an organism' environment (either external or internal). All living organisms (both plants and animals) respond to changes in their environment and as such an appropriate reaction or response is made. Also, stimulus arising from within the organism is known as internal stimulus while those from its environment are known as the external stimulus.
In organisms, the specialized cells that detect stimulus are generally known as sensory receptors while a group of these receptors is referred to as sense organ.
Since both plants and animals respond to environmental stimuli, it simply means that;
1. Both plants and animals have physiological cycles called circadian rhythms. This is a natural internal process that controls the physical, mental, and behavioral changes in living organisms such as the sleep-wake cycle. The circadian rhythm is simply the internal body "24 hour" clock.
2. The molecular processes determining how plants and animals perceive environmental changes are equally complex.
3. The molecular processes determining how plants and animals perceive environmental changes are often homologous. This simply means that, specific sense organs or sensory receptors would only respond to the stimulus they are primarily created to respond to. For example, the eyes can only be used to see and not smell, ear or taste.