Choose the correct statement/s about amphibolic pathways.

Options

A. Fatty acids are used as a substrate when they are converted into acetyle CoA to enter the respiratory pathways.
B. A pathway is said to be amphibolic when it can only perform catabolic activities like the breakdown of proteins into amino acids.
C. Glycerol enters the Kreb's cycle as PGAL.
D. Both (A) and (B)

Answer

To solve the question regarding amphibolic pathways, we need to analyze each of the given statements and determine which one is correct. Here’s a step-by-step breakdown:

### Step 1: Understand the Definition of Amphibolic Pathways
Amphibolic pathways are metabolic pathways that involve both catabolic (breakdown) and anabolic (synthesis) processes. This means they can both generate energy and use energy to build complex molecules.

**Hint:** Remember that "amphibolic" refers to pathways that can do both types of metabolic activities.

### Step 2: Analyze the First Statement
The first statement mentions that fatty acids are used as substrates when they are converted into acetyl-CoA to enter the respiratory pathway. This is true because fatty acids undergo beta-oxidation to form acetyl-CoA, which then enters the Krebs cycle (a key part of the respiratory pathway).

**Hint:** Think about how fatty acids are metabolized and their role in energy production.

### Step 3: Analyze the Second Statement
The second statement claims that a pathway is said to be amphibolic when it only performs catabolic activities, such as breaking down proteins into amino acids. This is incorrect because amphibolic pathways must involve both catabolic and anabolic processes.

**Hint:** Recall that amphibolic pathways are not limited to just one type of metabolic reaction.

### Step 4: Analyze the Third Statement
The third statement suggests that glycerol handles the Krebs cycle as phosphoglycerol acetaldehyde. This is misleading and incorrect. Glycerol can enter glycolysis and can be converted to dihydroxyacetone phosphate, but it does not directly handle the Krebs cycle in the manner described.

**Hint:** Consider the role of glycerol in metabolism and its connection to glycolysis rather than the Krebs cycle directly.

### Step 5: Analyze the Fourth Statement
The fourth statement claims that both A and B are correct. Since we have already established that statement B is incorrect, this option is also wrong.

**Hint:** If one part of a combined statement is false, the entire statement is false.

### Conclusion
After analyzing all the statements, the only correct statement is the first one regarding fatty acids being converted into acetyl-CoA to enter the respiratory pathway. Therefore, the correct answer is:

**Correct Answer:** Option 1