Question

21 multiple choice 2 points a karyotype would be least useful in determining whether a person had— a missing 23rd chromosome. an extra copy of chromosome 21. a recessive gene on the y chromosome. more than one x chromosome.

Explanation:

A karyotype shows the number and structure of chromosomes. It can detect missing or extra chromosomes. But it cannot directly show individual genes like a recessive gene on the Y - chromosome. Genes are at a molecular level and not visible in a karyotype which mainly shows chromosome morphology and number.

Answer:

C. a recessive gene on the Y chromosome.