Which of the following accurately describes an example of how materials can move across the cell membrane through active transport?

Question

• A protein acts as a channel to allow large, hydrophilic molecules to diffuse across the cell membrane.
• A protein acts as a pump and moves calcium ions from an area of low concentration to an area of high concentration.
• The cell membrane folds to surround a substance and bring the substance inside the cell during exocytosis.
• Water moves by osmosis from higher concentration to lower concentration by passing through proteins called aquaporins.

Answer 1

The statement that accurately describes an example of how materials can move across the cell membrane through active transport is:

A protein acts as a pump and moves calcium ions from an area of low concentration to an area of high concentration.

Active transport requires energy to move substances against their concentration gradient, and the example of a protein acting as a pump to move calcium ions from low to high concentration fits this definition.