Chimpanzees, Gorillas, and Orangutans Have DNA Sequences That Are Almost

question 19

Multiple Choice

Chimpanzees, gorillas, and orangutans have DNA sequences that are almost identical to those of humans; however, these genes are found on 24 pairs of chromosomes in apes, while humans have 23 pairs. The C2 chromosome in humans is a large chromosome with similar banding pattern and DNA sequences to two smaller chromosomes in apes (C2 and C4) . In addition it appears to have both a vestigial second centromere and telomere sequences in the middle of the strand.
-What could explain these observations?

• A)The human ancestor originally had 24 pairs but complete fusion of C2 and C4 occurred, reducing the total number of chromosomes.
• B)A nondisjunction event must have occurred in the human ancestor, increasing the overall ploidy.
• C)The loss of a chromosome is due to a deletion event in the human ancestor.
• D)C2 must have undergone an inversion with C4.
• E)There is not enough information to speculate.

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Definitions:

About Average

A term used to describe a value or performance that is near the middle or mean of a distribution or set of data.

Central Tendency

A statistical measure that identifies a single value as representative of the middle or centre of a distribution, commonly measured by mean, median, or mode.

Data

Information that has been translated into a form that is efficient for movement or processing.

Weighted Mean

An average where each data point contributes to the mean with a weight that reflects its importance or frequency.