Question

What processes could result in the net movement of a substance into a cell if the substance is more concentrated inside the cell than outside the cell?

Answer 1

To move a substance into a cell against its concentration gradient, active transport and endocytosis are primary mechanisms used, requiring cellular energy, such as ATP.

Step-by-step explanation:

If a substance is more concentrated inside the cell than outside, and it needs to move into the cell, certain processes can accomplish this against the concentration gradient. One such process is active transport, which requires cellular energy, often in the form of adenosine triphosphate (ATP), to move substances from an area of lower concentration outside the cell to a higher concentration inside the cell. Another process is endocytosis, where the cell engulfs material from the outside, forming vesicles that are brought into the cell. Both of these mechanisms allow for the accumulation of substances against their concentration gradients.

In contrast, processes like passive diffusion and facilitated diffusion usually allow substances to move from higher to lower concentration areas, which would not be applicable for a substance already in higher concentration within the cell. Co-transport, also known as secondary active transport, can use the gradient of one molecule to move another against its gradient. In the case of substances being more concentrated inside the cell, active transport and endocytosis are the key mechanisms that enable their movement into the cell, despite the concentration gradient.