Question

A fetus with which of the following abnormalities might not succumb soon after birth?

(a) monosomy

(b) trisomy 13

(c) trisomy 18

(d) trisomy 21

This question was addressed to me by my school teacher while I was bunking the class.

I'd like to ask this question from Cellular Reproduction in section DNA Replication and Repair, Cellular Reproduction of Cell Biology

Answer 1

The correct answer is:

(d) trisomy 21

Explanation:

Trisomy 21, also known as Down syndrome, is a chromosomal condition where an individual has three copies of chromosome 21 instead of the usual two. Unlike other trisomies such as trisomy 13 (Patau syndrome) or trisomy 18 (Edwards syndrome), which are associated with severe developmental issues and early mortality, individuals with trisomy 21 can survive into adulthood. While there are health challenges associated with Down syndrome (such as heart defects, developmental delays, and increased risk for certain health conditions), many individuals with trisomy 21 live fulfilling lives.

Other conditions:

• Monosomy (one missing chromosome) is typically lethal early in development.
• Trisomy 13 (Patau syndrome) and trisomy 18 (Edwards syndrome) are associated with severe developmental abnormalities and generally result in early death, often within the first year of life.

Thus, trisomy 21 (Down syndrome) is the only one among these that is associated with a possibility of surviving longer after birth.

Correct Answer: (d) trisomy 21