Natural selection cannot occur without what

Hello.

There are a couple things needed for natural selection.

Natural selection is organisms become comfortable and changer where they are newly located. Where they can live and get more off springs.

First, You will need heredity  which passes traits to an offspring.

Second, reproduction that is needed to to copy traits and give them to the offspring.

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.