As population density , competition increases.

As population density increases, competition increases.

Explanation:

Population density refers to total number of individuals present in unit area of the habitat. Competition refers to interaction among the individuals that have demand for a common essential resource. Increase in population density serves to increase the competition among individuals for the available resources such as food, space, water etc.

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.