LIFE SCIENCE

Detailed explanation-1: -A cross between two heterozygous parents gives 1 homozygous dominant: 2 heterozygous dominant: 1 homozygous recessive progeny in 1:2:1 ratio. This is due to segregation of two alleles of the same trait during gamete formation followed by random fusion of gametes.

Detailed explanation-2: -It describes the number of times a genotype would appear in the offspring after a test cross. For example, a test cross between two organisms with the same genotype, Rr, for a heterozygous dominant trait will result in offspring with genotypes: RR, Rr, and rr. In this example, the predicted genotypic ratio is 1:2:1.

Detailed explanation-3: -Answer and Explanation: The expected phenotypic ratio for a cross between two individuals that are heterozygous for a given trait is 3:1 for the dominant phenotype compared to the recessive phenotype. For example, one trait that Mendel studied in pea plants was whether the peas were yellow or green.

Detailed explanation-4: -A monohybrid cross results in a phenotypic ratio of 3:1 (dominant to recessive), and a genotypic ratio of 1:2:1 (homozygous dominant to heterozygous to homozygous recessive).