Why do cells need to harness the energy of 'falling electrons during the electron transport chain?

Hey me with this one❤☺❤ how do you say that a cell also has a life span and death like an organism? give one example.

Flock x flock y flock z total pieces of food eaten (from previous page) 147 93 60 food percentage* % % % simulated number of birds in flock for 3rd generation** * divide each flock's total pieces of food by 300, the total number of pieces of food eaten. ** multiply the food percentage for each flock by the total number of birds (30).

During the winter, this species of fox has white fur, but in the summer, it has brown fur. what environmental change may have lead to this fox's fur color? snow cover increase in sun's brightness volcanic eruption global warming