Genetics: mitochondrial inheritance: 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 · Genetics: mitochondrial inheritance

Sample item

Which inheritance pattern is typical of mitochondrial disorders?

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

The answer and the reasoning

D. Affected mothers can transmit disease to all children, whereas affected fathers do not transmit it

Mitochondrial DNA is inherited almost exclusively through the ovum, so affected mothers may transmit variants to all offspring while affected fathers do not transmit mitochondrial DNA. Heteroplasmy affects severity.

Option by option

  • A. Transmission follows the Y chromosome

    Y-linked traits pass from father to son.

  • B. Only sons are affected

    Only-son transmission suggests Y-linked inheritance.

  • C. Disease skips every generation

    Skipping generations is not the defining mitochondrial rule.

  • D. Affected mothers can transmit disease to all children, whereas affected fathers do not transmit it (correct)

    Correct. Maternal inheritance is the defining pattern.

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 D, Affected mothers can transmit disease to all children, whereas affected fathers do not transmit it. Mitochondrial DNA is inherited almost exclusively through the ovum, so affected mothers may transmit variants to all offspring while affected fathers do not transmit mitochondrial DNA.

Why is "Transmission follows the Y chromosome" not the answer?

Y-linked traits pass from father to son.

Why is "Only sons are affected" not the answer?

Only-son transmission suggests Y-linked inheritance.

Why is "Disease skips every generation" not the answer?

Skipping generations is not the defining mitochondrial rule.

What concept does this question test?

It tests Genetics: mitochondrial inheritance in Biochemistry. Heteroplasmy affects severity.

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 Genetics: mitochondrial inheritance?

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.