Question

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The picture shows the chromosomes of a human.
What caused the chromosomal alteration in number 21?

Group of answer choices

a part of a chromosome was lost (deletion)

a duplicated chromosome failed to separate (nondisjunction)

part of one chromosome attached to another chromosome (translocation)

some of the genes on a chromosome were reversed (inversion)

Answer 1

A duplicated chromosome failed to separate (nondisjunction)

Step-by-step explanation:

Answer 2

Answer: A duplicated chromosome failed to separate (nondisjunction)

Step-by-step explanation:

If nondisjunction occurs during meiosis I, homologous chromosomes fail to separate. This produces abnormal gametes that contain two members of the affected chromosome or none. This is why there is an extra chromosome in the 21 chromosomes.