Passage II

Plants from Species X can be tall or short, and they can have red, pink, or white flowers. Height in Species X plants is controlled by Gene T, which has 2 alleles, T and t. Flower color in Species X plants is controlled by Gene R, which also has 2 alleles, R and r. To determine how height and flower color are inherited in Species X, a student conducted the following crosses.

Cross 1

Two tall Species X plants, each with the genotype Tt, were crossed. The numbers and phenotypes of the resulting offspring are shown in Table 1.

Cross 2

Two pink-flowered Species X plants, each with the genotype Rr, were crossed, and the numbers and phenotypes of the resulting offspring are shown in Table 2.

Cross 3

Two Species X plants, each with the genotype TtRr, were crossed. The numbers, genotypes, and phenotypes of the resulting offspring are shown in Table 3.

11. Suppose a short red-flowered Species X crossed plant is with a short pink-flowered Species X plant. The percent of the resulting offspring with the genotype ttRr will most likely be closest to which of the following?

Answer and Explanation

Your Answer is

Correct Answer is C

Explanation

According to table 3, it can be seen that the genotype of short & red is ttRR, and the genotype of short & pink is ttRr. As parents, 100% of their offspring are tt, so only Gene R is considered. 50% of the offspring are RR, and the other 50% are Rr, so the probability of producing ttRr is 50%