AP BIOLOGY

Detailed explanation-1: -The genotype is represented by letter combinations, such as TT, Tt, and tt. When an organism has two of the same alleles for a specific gene, it is homozygous (homo means “same") for that gene. An organism can be either homozygous dominant (TT) or homozygous recessive (tt).

Detailed explanation-2: -An organism can be either homozygous dominant ( TT ) or homozygous recessive ( tt ). If an organism has two different alleles ( Tt ) for a certain gene, it is known as heterozygous (hetero-means different).

Detailed explanation-3: -Homozygous means that the organism has two copies of the same allele for a gene. An organism can be homozygous dominant, if it carries two copies of the same dominant allele, or homozygous recessive, if it carries two copies of the same recessive allele.

Detailed explanation-4: -Complete answer: When cross takes place between Tt and tt two different types of alleles are form, Tt X tt = Tt, Tt, tt, and tt. The genotypic ratio for this cross is 1:1 and the phenotypic ratio is 1:1, where Tt is heterozygous dominant and tt is heterozygous recessive. This type of cross is a test cross.

Detailed explanation-5: -The notation tt means the homozygous condition, wherein the homologous pair contains same alleles of a gene. Alleles are different forms of one gene. In the pea plant, tall and dwarf are the two contrasting traits for stem height. ‘t’ is used for dwarfness, which is recessive.