Biochemistry : Carbohydrate Metabolism

Study concepts, example questions & explanations for Biochemistry

varsity tutors app store varsity tutors android store

Example Questions

Example Question #211 : Carbohydrate Metabolism

During lactic acid fermentation, what is the final electron acceptor?

Possible Answers:

NADH

Ethanol

Pyruvate

Oxygen

Carbon dioxide

Correct answer:

Pyruvate

Explanation:

Under normal aerobic conditions, the final electron acceptor at the end of the electron transport chain is oxygen. However, fermentation occurs when there is no oxygen available. Therefore, something else must act as the final electron acceptor. In lactic acid fermentation, NADH is the electron carrier that ultimately carries them to pyruvate. Pyruvate is reduced to lactic acid, and thus, acted as the final electron acceptor.

Example Question #1 : Ethanol Fermentation

Multiple studies have shown that drinking lots of alcohol can lead to an increase in body fat. 

From a biochemical perspective, what aspect of alcohol metabolism may suggest that it contributes to an increase in body fat?

Possible Answers:

Production of acetyl-CoA

Formation of acetaldehyde

Formation of acetic acid

Formation of acetals and ketals 

Correct answer:

Production of acetyl-CoA

Explanation:

Fats are broken down into acetyl-CoA to be used for energy. However, large quantities of alcohol will produce large quantities of acetyl-CoA when metabolized. Acetyl-CoA can be converted into fatty acids when it is in excess. Then fatty acids can assemble into triglycerides and be stored as fat.

Learning Tools by Varsity Tutors