Population genetics: Hardy-Weinberg calculation: 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 · Population genetics: Hardy-Weinberg calculation

Sample item

An autosomal recessive disorder affects 1 in 10,000 live births in a population in Hardy-Weinberg equilibrium. What is the approximate carrier frequency?

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

The answer and the reasoning

C. About 1 in 50

Disease frequency q squared is 1/10,000, so q is 1/100, which is 0.01. The frequency of the normal allele p is 0.99. Carriers are 2pq, which is 2 times 0.99 times 0.01, about 0.0198, or roughly 2%, which is 1 in 50.

Option by option

  • A. About 1 in 100

    1 in 100 is the allele frequency q, not the carrier frequency.

  • B. About 1 in 10,000

    1 in 10,000 is the disease frequency q squared.

  • C. About 1 in 50 (correct)

    2pq is about 0.02, which is 1 in 50.

  • D. About 1 in 200

    1 in 200 would result from halving q instead of doubling it to get 2pq.

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, About 1 in 50. Disease frequency q squared is 1/10,000, so q is 1/100, which is 0.

Why is "About 1 in 100" not the answer?

1 in 100 is the allele frequency q, not the carrier frequency.

Why is "About 1 in 10,000" not the answer?

1 in 10,000 is the disease frequency q squared.

Why is "About 1 in 200" not the answer?

1 in 200 would result from halving q instead of doubling it to get 2pq.

What concept does this question test?

It tests Population genetics: Hardy-Weinberg calculation in Biochemistry. 01. The frequency of the normal allele p is 0.99. Carriers are 2pq, which is 2 times 0.99 times 0.01, about 0.0198, or roughly 2%, which is 1 in 50.

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 Population genetics: Hardy-Weinberg calculation?

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.