Carbohydrate metabolism: glycaemic index: 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 · Carbohydrate metabolism: glycaemic index

Sample item

A dietician tests a food containing 50 g of available carbohydrate. The incremental 2-hour area under the blood glucose curve is 35 units. The same person, eating 50 g of glucose on another day, has an area of 50 units. What is the glycaemic index of the test food?

A15B35C70D143

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

The answer and the reasoning

C. 70

Glycaemic index is the incremental glucose area after a test food divided by the area after an equal carbohydrate load of the reference food, multiplied by 100. Here 35 divided by 50 gives 0.7, so the index is 70, which lies in the high range. Fibre, fat and protein in a food usually slow absorption and lower the index.

Option by option

A. 15
This subtracts the two areas instead of calculating a ratio.
B. 35
This is the raw area of the test food and ignores division by the reference area.
C. 70 (correct)
Correct. 35 divided by 50 multiplied by 100 equals 70.
D. 143
This inverts the ratio by dividing the reference area by the test area.

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.

Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is C, 70. Glycaemic index is the incremental glucose area after a test food divided by the area after an equal carbohydrate load of the reference food, multiplied by 100.

Why is "15" not the answer?

This subtracts the two areas instead of calculating a ratio.

Why is "35" not the answer?

This is the raw area of the test food and ignores division by the reference area.

Why is "143" not the answer?

This inverts the ratio by dividing the reference area by the test area.

What concept does this question test?

It tests Carbohydrate metabolism: glycaemic index in Biochemistry. Here 35 divided by 50 gives 0.7, so the index is 70, which lies in the high range. Fibre, fat and protein in a food usually slow absorption and lower the index.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Carbohydrate metabolism: glycaemic index?

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.