Down syndrome is also known as trisomy-21 because individuals with Down syndrome ____.

Question

Quizplus · Accepted Answer

Down syndrome occurs when there is a third copy of the 21st chromosome, hence it is also called trisomy-21. Option A is incorrect as distinctive facial features are observable after birth, not during pregnancy. Option B is incorrect as temperament patterns cannot be accurately determined at such an early stage of development. Option D is incorrect as a pair of chromosomes consists of two chromosomes, not 21.

Down Syndrome Is Also Known as Trisomy-21 Because Individuals with Down