Upon examination of a zygote, a developmental biologist discovers that it possesses 47 chromosomes. What does this indicate?
A)The zygote resulted from polyspermy (multiple fertilizations of the same oocyte)by two sperm cells
B)The zygote is a normal, healthy diploid zygote
C)Either the sperm or the egg received an extra chromosome as the result of a meiotic error
D)Either the sperm or the egg had one less chromosome than normal as the result of a meiotic error

Question

Quizplus · Accepted Answer

The presence of an extra chromosome suggests that either the sperm or the egg had an extra chromosome, likely as the result of a meiotic error such as nondisjunction. This is known as aneuploidy, and can lead to genetic disorders such as Down syndrome. It is not necessarily indicative of polyspermy or a missing chromosome.

Upon Examination of a Zygote, a Developmental Biologist Discovers That