Description 3

This is incorrect!

Dr. Foster: ‘Unfortunately, that description doesn’t ring true when it comes to distinguishing homozygote and heterozygote. Remember that Professor York emphasized how each pair of alleles can be identical or different, not both at the same time. It might help to revisit your lecture notes or the slides from last week to remind yourself which terms apply to individuals who have two matching alleles (like AA or aa) versus those who have two different alleles (Aa). Once you clarify that, have another look at the options and see which one precisely states the difference.’

You try to refresh your memory on homozygote and heterozygote terminologies and pick a new answer! 

Description 1: Homozygote for the gene is when the two alleles in an individual are the same (AA or aa).Heterozygote for the gene is when the two alleles are different (Aa).

Description 2: Heterozygote for the gene is when the two alleles in an individual are the same (AA or aa). Homozygote for the gene is when the two alleles are different (Aa).