How do positive and negative feedback loops work together?.

i think that d. wind is the answer.   i missed the question when i answered a. currents.

because the light is a great source of energy for the plants to survive. (i hope this )

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.