Nutrition: essential fatty acids: 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 · Nutrition: essential fatty acids

Sample item

Which fatty acid is essential in the human diet because it cannot be synthesized de novo?

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

The answer and the reasoning

A. Linoleic acid

Linoleic acid is an essential omega-6 fatty acid that humans cannot synthesize because they lack desaturases beyond carbon 9. Alpha-linolenic acid is also essential.

Option by option

  • A. Linoleic acid (correct)

    Correct. Linoleic acid must be obtained from diet.

  • B. Palmitic acid

    Palmitate can be synthesized from acetyl-CoA.

  • C. Stearic acid

    Stearate can be synthesized endogenously.

  • D. Oleic acid

    Oleate can be synthesized from stearate by delta-9 desaturase.

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 A, Linoleic acid. Linoleic acid is an essential omega-6 fatty acid that humans cannot synthesize because they lack desaturases beyond carbon 9.

Why is "Palmitic acid" not the answer?

Palmitate can be synthesized from acetyl-CoA.

Why is "Stearic acid" not the answer?

Stearate can be synthesized endogenously.

Why is "Oleic acid" not the answer?

Oleate can be synthesized from stearate by delta-9 desaturase.

What concept does this question test?

It tests Nutrition: essential fatty acids in Biochemistry. Alpha-linolenic acid is also essential.

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 Nutrition: essential fatty acids?

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.