Activity of succinic dehydrogenase involves the following in TCA
cycle.

Options

A. NAD
B. FAD
C. GDP
D. ATP

Answer

To solve the question regarding the activity of succinic dehydrogenase in the TCA cycle, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the TCA Cycle**: The TCA cycle, also known as the Krebs cycle or citric acid cycle, is a crucial metabolic pathway that plays a key role in cellular respiration. It involves a series of chemical reactions used by all aerobic organisms to generate energy.

**Hint**: The TCA cycle is essential for energy production in cells and involves multiple enzymes and substrates.

2. **Identify the Role of Succinic Dehydrogenase**: Succinic dehydrogenase is an enzyme that catalyzes the oxidation of succinate to fumarate. This reaction is a part of the TCA cycle.

**Hint**: Focus on the specific reaction that succinic dehydrogenase facilitates within the TCA cycle.

3. **Recognize the Reaction Details**: During the oxidation of succinate, succinic dehydrogenase removes two hydrogen atoms from succinate. These hydrogen atoms are transferred to FAD (flavin adenine dinucleotide), reducing it to FADH2.

**Hint**: Remember that the reduction of FAD to FADH2 is a key aspect of the reaction catalyzed by succinic dehydrogenase.

4. **Determine the Products of the Reaction**: The main products of the reaction catalyzed by succinic dehydrogenase are fumarate and FADH2. FADH2 then enters the mitochondrial electron transport chain to contribute to ATP production.

**Hint**: Consider what happens to FAD after it is reduced and how it contributes to energy production.

5. **Select the Correct Answer**: Based on the information, the activity of succinic dehydrogenase specifically involves FAD, as it is reduced to FADH2 during the reaction.

**Hint**: Look for the component that is directly involved in the reaction facilitated by succinic dehydrogenase.

### Final Answer:
The activity of succinic dehydrogenase in the TCA cycle involves **FAD**.