AP BIOLOGY

Detailed explanation-1: -As shown in the figure a cross between two heterozygous tall plants results in 25% homozygous tall, 50% heterozygous tall and 25% dwarf plants. Thus the correct answer is option C.

Detailed explanation-2: -In pea plants, tall stem trait (T) is dominant over the dwarf stem trait (t). A cross involving homozygous tall and homozygous dwarf plants produce tall plants.

Detailed explanation-3: -The phenotypic ratio of breeding tall pea plants to breeding dwarf pea plants shall be 1:1.

Detailed explanation-4: -Mendel observed that the offspring of this cross (called the F1 generation) were all tall plants! Next, Mendel let the F1 generation self-pollinate. That means the tall plant offspring were crossed with each other. He found that 75% of their offspring (the F2 generation) were tall, while 25% were short.

Detailed explanation-5: -50% heterozygous tall pea plants would be obtained in F2 generation when tall heterozygous pea plants are selfed.