Question

The 2-carbon compound that enters the citric acid cycle joins with which of the following molecules before it begins its turn around the cycle?

a) Acetyl-CoA
b) Pyruvate
c) Oxaloacetate
d) Citrate

Answer 1

The 2-carbon compound acetyl CoA combines with oxaloacetate to form citrate, marking the start of the citric acid cycle.

Step-by-step explanation:

The 2-carbon compound that enters the citric acid cycle joins with the molecule oxaloacetate before it begins its turn around the cycle. The two-carbon compound is known as acetyl CoA, which is formed from the oxidative decarboxylation of pyruvate. When acetyl CoA combines with oxaloacetate, it forms a six-carbon compound known as citrate or citric acid, marking the beginning of the citric acid cycle.