In which of the following situations does the cell use active transport?

A. Oxygen moves into cells through the process of diffusion

O

B. Sodium ions move into the cell from areas of lower

concentrations.

O

C. Proteins allow small polar molecules to move across the cell

membrane along the concentration gradient.

D. A cell uses its membrane to surround a substance and bring it into

the cell in a vesicle.

The correct option is B. Sodium ions move into the cell from areas of lower

concentrations.

Explanation:

Active transport can be described as a process in which molecules move from an area of lower concentration to an area of higher concentration against the concentration gradient. Energy is required for the process of active transport to occur.

In the option B, sodium ions are moving into the cell from areas which have a low concentration of sodium i. e against the concentration gradient. Hence, option B tells that the sodium ions will move inside the cell by the process of active transport.