Question

Active transport
A) Releases energy
B) Requires energy
C) Produces ATP
D) Produces a toxic substance

Answer 1

Active transport is the movement of ions across the cell membrane against the concentration gradient. An example of active transport is uptake of minerals and ions into root hair cells.

Complete answer:
To answer this question, we must know about the mechanism of active transport.
Active transport is the movement of ions and molecules across the cell membrane against the concentration gradient at the expenditure of energy. The substances that are transported by the method of active transport are metal ions like $Na^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$.

An example of active transport is sodium and potassium pump. In this sodium is pumped out of the cell and potassium into the cell at the expenditure of energy. Active transport also takes place in the internal lining of the small intestine.

In the plant cells active transport takes place in the root cells. The minerals and salts exist in very dilute solutions. The root hair cells absorb these ions against the concentration gradient which uses energy. This movement is driven by a hydrogen pump or proton pump.

Thus the correct answer is option (B). Active transport requires energy

Note: Active transport uses cellular energy for the movement of ions against the concentration gradient whereas passive transport uses kinetic energy and entropy for the movement of ions along the concentration gradient. Active transport takes place for the accumulating high concentration of molecules like ions, glucose, amino acids etc.