Question

Define active transport:

a. Movement of materials across a membrane that requires an input of energy from a cell.
b. Process in which atoms and molecules move from an area where they are more concentrated to an area where they are less concentrated.
c. Movement of materials across a membrane that does not require energy from the cell.
d. The diffusion of water across a semipermeable membrane.

Answer 1

Active transport is the process by which cells move substances against a concentration gradient using energy, typically from ATP. It's crucial for maintaining homeostasis by regulating the concentration of ions and molecules inside and outside of the cell.

Step-by-step explanation:

Active transport is the movement of substances across a cell's plasma membrane that requires energy input from the cell. Unlike passive transport, which moves substances along a concentration gradient from an area of higher concentration to an area of lower concentration, active transport requires energy to move substances against their concentration gradient, typically from an area of lower concentration to an area of higher concentration or to move large substances across the membrane.

Adenosine triphosphate (ATP) is often the source of energy used in active transport processes, such as in the sodium-potassium pump, where sodium is pumped out of the cell while potassium is pumped in. This process is essential for maintaining cellular homeostasis and is an example of the body's ability to maintain a stable internal environment. Vesicle transport is another type of active transport that utilizes energy to move larger molecules or particles across cell membranes inside vesicles.