Prove that light conditions play an important role in the life of organisms.

The main reference point in time for almost all living organisms (with the exception of only Homo sapiens) is the so-called “biological clock pendulum”, which directly depends on daylight hours. That is, the body at a subconscious level begins to understand that now it is time for it to sleep, but the sun has risen – and it is time to stay awake (in the event that we are talking about nocturnal predators, the situation is exactly the opposite).
And, mind you, daylight is only a factor that starts the biological clock.