Which of the following statements describes active transport?(1 point)
Responses
Net movement of a substance from a region of higher concentration to a region of lower concentration
Net movement of a substance from a region of higher concentration to a region of lower concentration
Movement of a specific substance across a membrane.
Movement of a specific substance across a membrane.
Spontaneous movement of a substance through a semipermeable membrane.
Spontaneous movement of a substance through a semipermeable membrane.
[Movement of a substance against a concentration gradient. D]
Movement of a substance against a concentration gradient.
The statement that describes active transport is: 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 understand why this is the correct answer, let's break down the options and explain each one:
1. "Net movement of a substance from a region of higher concentration to a region of lower concentration" - This is actually describing passive transport, specifically diffusion. Diffusion is the process where particles move from an area of high concentration to low concentration without the input of energy.
2. "Movement of a specific substance across a membrane" - This statement is too general and can apply to both passive and active transport. It does not specifically describe active transport.
3. "Spontaneous movement of a substance through a semipermeable membrane" - This statement is describing passive transport, specifically osmosis. Osmosis is the movement of water molecules from an area of low solute concentration to an area of high solute concentration through a semipermeable membrane.
4. "Movement of a substance against a concentration gradient" - This statement correctly describes active transport. It is the process by which substances are actively pumped or transported across a membrane, against their concentration gradient. This movement requires the input of energy, usually in the form of ATP (adenosine triphosphate).
To recap, active transport is the movement of a substance against its concentration gradient through a membrane, requiring energy input.