Question

multiple choice question
transport of molecules across the membrane using ion gradients is termed ______.

abc transport
facilitated transport
primary active transport
secondary active transport

Explanation:

To solve this, we analyze each option:

• ABC transport: Uses ATP - binding cassette proteins, not ion gradients. Eliminate.
• Facilitated transport: Passive, uses transporters but no ion gradients for energy. Eliminate.
• Primary active transport: Uses ATP directly (e.g., Na⁺/K⁺ pump), not ion gradients as an energy source. Eliminate.
• Secondary active transport: Uses the energy from ion gradients (established by primary active transport) to move other molecules across the membrane. This matches the description.

Answer:

D. secondary active transport