A) Which of the following statements describes active transport? (1 point)
Movement of a specific substance across a membrane.
Spontaneous movement of a substance through a semipermeable membrane.
[Movement of a substance against a concentration gradient. D]
Net movement of a substance from a region of higher concentration to a region of lower concentration
Movement of a substance against a concentration gradient.
The correct statement that describes active transport is:
Movement of a substance against a concentration gradient.
To determine which statement describes active transport, we can go through each option and see which one fits the definition.
A) Movement of a specific substance across a membrane.
This statement is a general description of any type of substance movement across a membrane and does not specifically refer to active transport.
B) Spontaneous movement of a substance through a semipermeable membrane.
This statement describes passive transport, not active transport. Passive transport does not require energy and includes processes like diffusion and osmosis.
C) Movement of a substance against a concentration gradient.
This option accurately describes active transport. Active transport refers to the movement of molecules or ions across a membrane against their concentration gradient, meaning from an area of lower concentration to an area of higher concentration. This process requires the expenditure of energy.
D) Net movement of a substance from a region of higher concentration to a region of lower concentration.
This statement describes passive transport, specifically diffusion, where molecules naturally move from an area of higher concentration to an area of lower concentration, without the need for energy.
Based on this analysis, the correct answer is C) Movement of a substance against a concentration gradient.