Question

The conversion of FAD to FADH$_2$ is a

• A. One-step process with radical intermediates
• B. Two-step process with ionic intermediates
• C. Two-step process with radical intermediates
• D. One-step process with ionic intermediates

Hint:

FAD reduction occurs stepwise via semiquinone radical → important in electron transport chain.

Answer 1

The Correct Option is C

Concept: FAD (Flavin Adenine Dinucleotide) undergoes reduction to FADH$_2$ by accepting two electrons and two protons. This process occurs via intermediate formation.

Step 1: Understand electron transfer.
FAD accepts electrons in two steps:
• First electron → forms semiquinone radical (FADH$\cdot$)
• Second electron → forms FADH$_2$

Step 2: Identify nature of intermediates.
The intermediate formed is a radical species (semiquinone form).

Step 3: Determine process type.
Since electrons are added in two steps and involve a radical intermediate: \[ \text{Two-step process with radical intermediates} \]

Step 4: Final conclusion.
Thus, the correct description is: \[ Two-step process with radical intermediates \]