Active transport

The energy for active transport comes from respiration, which produces ATP (adenosine triphosphate). ATP is then used to power the protein carriers that move molecules or ions against their concentration gradient.

Active transport moves particles *against* their concentration gradient, from an area of lower concentration to an area of higher concentration. This is the opposite of passive transport processes like diffusion.

Protein carriers (or carrier proteins) within the cell membrane are directly involved in active transport. These proteins bind to specific molecules or ions and facilitate their movement across the membrane using energy.

Active transport allows root hair cells to absorb mineral ions (like nitrates and phosphates) from the soil, even when the concentration of these ions is lower in the soil than in the root hair cell. This is essential for plant growth.

Active transport is used in the small intestine to absorb glucose and amino acids, even when their concentration is lower in the gut than in the blood. This ensures all available nutrients are absorbed.

If respiration was inhibited, the plant would produce less ATP. Since active transport requires ATP, the uptake of ions by root hairs would decrease significantly, potentially harming the plant's growth and health.

Active transport moves substances against a concentration gradient and requires energy (ATP), while diffusion moves substances down a concentration gradient and does not require energy. Diffusion is a passive process, while active transport is an active process.

Sodium ions are actively transported out of nerve cells after an action potential to restore the resting membrane potential. Potassium ions are actively transported into the nerve cell at the same time.

Protein carriers have specific binding sites for the molecules or ions they transport. When the molecule binds, the protein changes shape, using energy from ATP, to move the molecule across the membrane and release it on the other side.