Question
Which of the following statements describes active transport?(1 point)
Responses
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. D]
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 substance against a concentration gradient.
The correct statement that describes active transport is: [Movement of a substance against a concentration gradient. D]
To determine which of the statements describes active transport, let's go through each option and explain how to find the answer.
Statement 1: "Movement of a specific substance across a membrane."
This statement is very general and does not specify any details about the movement. It could refer to any type of movement, including passive transport. We can't conclude that it describes active transport based on this information.
Statement 2: "Spontaneous movement of a substance through a semipermeable membrane."
This statement describes passive transport, where substances move across a membrane without the need for any external energy source. It does not describe active transport.
Statement 3: "[Movement of a substance against a concentration gradient. D]"
This statement accurately describes active transport. Active transport refers to the movement of substances across a membrane using energy, usually against the concentration gradient. This requires the use of specialized membrane proteins and ATP (adenosine triphosphate), the energy currency of cells.
Statement 4: "Net movement of a substance from a region of higher concentration to a region of lower concentration"
This statement describes passive transport, specifically a process called diffusion. Diffusion is the net movement of substances from an area of higher concentration to an area of lower concentration. It does not involve an external energy source and is not considered active transport.
Based on the explanation provided, the correct answer is Statement 3: "Movement of a substance against a concentration gradient."