a somatic cell in an animal is 2n=12. An egg cell from that same animal is n=5

Question

the most likely explanation for the amount of genetic material in the egg cell is?

a the cell divided one time too many

b- the dna did not get replicated prior to meiosis

c. nondisjunction occurred in mitosis

d. nondisjunction occurred in meiosis I or meiosiss II

e. more than one of these responses is possible

Answer 1

The answer is D.

The egg cell has undergone meiosis and has 1 set off chromosomes and a total of 5 chromosomes.

nondisjunction is the failure of chromosomes or chromatids to separate.  Since the normal animal cell contains 12 total chromosomes and 2 copies of each chromosome, we should expect the egg to contain half or 6.  Depending on where nondisjunction occurs (meiosis 1 or meiosis 2) either one egg or two eggs will end up with an extra chromosome and one or two eggs will end up missing a chromosome.