Lipid metabolism: fatty liver: practice question

A Biochemistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Biochemistry · Lipid metabolism: fatty liver

Sample item

A malnourished man on long-term parenteral nutrition free of choline develops hepatic steatosis with raised transaminases. Which mechanism best explains the fat accumulation?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Impaired phosphatidylcholine synthesis reducing VLDL assembly and export

Choline is needed for phosphatidylcholine, a surface phospholipid of VLDL. Without it, triacylglycerol cannot be packaged and exported from hepatocytes, so fat accumulates. Choline is therefore called a lipotropic factor, along with methionine and betaine, and similar steatosis follows protein malnutrition and alcohol.

Option by option

  • A. Decreased hepatic synthesis of fatty acids

    Reduced fatty acid synthesis would lower hepatic triacylglycerol rather than raise it.

  • B. Increased carnitine palmitoyltransferase I activity

    Higher CPT-I activity would promote fat oxidation and reduce, not increase, hepatic fat.

  • C. Impaired phosphatidylcholine synthesis reducing VLDL assembly and export (correct)

    Correct. Lack of phospholipid prevents VLDL assembly and secretion of triacylglycerol.

  • D. Increased lipoprotein lipase activity in the liver

    Lipoprotein lipase acts on capillary endothelium of extrahepatic tissues and its excess would not cause steatosis.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is C, Impaired phosphatidylcholine synthesis reducing VLDL assembly and export. Choline is needed for phosphatidylcholine, a surface phospholipid of VLDL.

Why is "Decreased hepatic synthesis of fatty acids" not the answer?

Reduced fatty acid synthesis would lower hepatic triacylglycerol rather than raise it.

Why is "Increased carnitine palmitoyltransferase I activity" not the answer?

Higher CPT-I activity would promote fat oxidation and reduce, not increase, hepatic fat.

Why is "Increased lipoprotein lipase activity in the liver" not the answer?

Lipoprotein lipase acts on capillary endothelium of extrahepatic tissues and its excess would not cause steatosis.

What concept does this question test?

It tests Lipid metabolism: fatty liver in Biochemistry. Without it, triacylglycerol cannot be packaged and exported from hepatocytes, so fat accumulates. Choline is therefore called a lipotropic factor, along with methionine and betaine, and similar steatosis follows protein malnutrition and alcohol.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Lipid metabolism: fatty liver?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.