AP BIOLOGY

Detailed explanation-1: -Recessive inheritance means both genes in a pair must be abnormal to cause disease. People with only one defective gene in the pair are called carriers. These people are most often not affected with the condition.

Detailed explanation-2: -A carrier, as related to genetics, is an individual who “carries” and can pass on to its offspring a genomic variant (allele) associated with a disease (or trait) that is inherited in an autosomal recessive or sex-linked manner, and who does not show symptoms of that disease (or features of that trait).

Detailed explanation-3: -If a person has only one gene for a disorder, he or she is known as a carrier. Carriers often do not know that they have a gene for a disorder. They usually do not have symptoms or have only mild symptoms.

Detailed explanation-4: -This is due to the fact that, in general, females carry two X chromosomes (XX), while males carry one X and one Y chromosome (XY). Therefore, females carry two copies of each X-linked gene, but males carry only one copy each of X-linked and Y-linked genes. Females carry no copies of Y-linked genes.