Question

Saguaro cacti are very tall cylindrical plants that usually have two L-shaped arms, one one each side. In the Saguaro arm length is controlled by a single gene with arms of the same length (A) being dominant to arms of different lengths (a). If two cacti that are heterozygous for arm length are mated, the offspring would be expected to show which phenotypic ratio?

Answer 1

The expected phenotypic ratio for the offspring of two saguaro cacti that are heterozygous for arm length is 3:1, with three-quarters showing the dominant trait of arms of the same length and one-quarter showing the recessive trait of arms of different lengths.

Step-by-step explanation:

When two saguaro cacti that are heterozygous for arm length (Aa) are crossed, Mendelian genetics predict the offspring will exhibit three possible genotypes: AA, Aa, and aa. The dominant phenotype, arms of the same length, is expressed by both AA and Aa genotypes, while the recessive phenotype, arms of different lengths, is expressed only by the aa genotype. According to Mendel's principles, the expected phenotypic ratio for this cross would be 3:1, where three-quarters of the offspring will display the dominant phenotype (arms of the same length) and one-quarter will display the recessive phenotype (arms of different lengths).

The expected phenotypic ratio for offspring from mating two heterozygous Saguaro cacti for arm length is 1:2:1.

The offspring from mating two heterozygous Saguaro cacti for arm length (Aa x Aa) would be expected to show a phenotypic ratio of 1:2:1. This means that for every one cactus with both arms of the same length (AA), there will be two cacti with arms of different lengths (Aa) and one cactus with both arms of different lengths (aa).