AP BIOLOGY

Detailed explanation-1: -Recessive alleles are denoted by a lowercase letter (a versus A). Only individuals with an aa genotype will express a recessive trait; therefore, offspring must receive one recessive allele from each parent to exhibit a recessive trait.

Detailed explanation-2: -Dominant alleles are seen as an uppercase of a letter; for example, B. Recessive alleles are seen as a lower case of a letter; b. In order for a person to show the dominant trait, one of the person’s parents must have the dominant trait (which is an uppercase letter).

Detailed explanation-3: -Recessive alleles are always represented by lowercase letters. In order for an organism to express a recessive allele, it must have received a recessive allele from both of its parents. In the above Punnett square diagram, two heterozygous dominant parents are mating.

Detailed explanation-4: -A dominant allele is denoted by a capital letter (A versus a). Since each parent provides one allele, the possible combinations are: AA, Aa, and aa. Offspring whose genotype is either AA or Aa will have the dominant trait expressed phenotypically, while aa individuals express the recessive trait.

Detailed explanation-5: -To distinguish among different alleles, the abbreviation is followed by an upper-case letter (e.g., the rpoB gene encodes the subunit of RNA polymerase). Protein symbols are not italicized, and the first letter is upper-case (e.g., RpoB).