Variations are beneficial for the survival of the species. Populations of organisms fill well-defined places, or niches, in the ecosystem, using their ability to reproduce.However, if some variations were to be present in a few individuals in these populations, there would be some chance for them to survive.
They are all necessary for photosynthesis to occur.
The answer would be pituitary gland.
Completed sentence: Growth hormone is secreted by the pituitary gland while we sleep.
Answer:
it's not clear
and not seeing the system clearly