Question

For active transport, energy can be derived from:
(A). ATP
(B). Light
(C). Electron movement
(D). NADH
Choose the correct answer from the options given below:

• A. (A), (B) and (C) only.
• B. (A), (B) and (D) only.
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

The three fundamental direct energy sources for primary active transport pumps across life are ATP, light, and electron transport (redox energy).
NADH is a precursor substrate, not the direct driver of the membrane pump.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Active transport is the movement of solutes across a biological membrane against their concentration or electrochemical gradient.
This endergonic process must be coupled with an exergonic process that provides energy.

Step 2: Detailed Explanation:
Primary active transporters directly couple transport to an energy-yielding chemical reaction:
- ATP hydrolysis (A): Used by ATPases (e.g., \(Na^+/K^+\) ATPase) to pump ions.
- Light energy (B): Used by light-driven pumps (e.g., bacteriorhodopsin in halophilic archaea) to generate proton gradients.
- Electron movement Redox reactions (C): Used by the mitochondrial and chloroplast electron transport chains to actively pump protons across membranes.
- NADH (D): While NADH is the electron donor that feeds into the respiratory chain, it is the actual movement of electrons through the respiratory complexes (C) that directly drives the active transport of protons.
Thus, ATP, Light, and Electron movement are the direct primary energy sources for active transport.

Step 3: Final Answer:
The correct answer is (A), (B) and (C) only, corresponding to option (A).