Question

As a student crosses to the breeding pen, one with green pots and the other with yellow pots, what result will the student find in generation 2?

a) CA 75% yellow, 25% green
b) CE 100% yellow
c) OC 75% green, 25% yellow
d) Salamet

Answer 1

In a cross of true-breeding green-seeded plants with true-breeding yellow-seeded plants, one would expect 100% yellow seeds in the F1 generation due to yellow being dominant. In the F2 generation, when F1 plants are crossed, the expected ratios are 75% yellow seeds and 25% green seeds.

Step-by-step explanation:

When performing a cross involving seed color in garden pea plants, and considering that yellow seed color is dominant over green seed color, the expected result for the F1 offspring would be 100 percent yellow seeds if we cross true-breeding plants with green seeds with true-breeding plants with yellow seeds.

In genetic terms, this is because the green plants would have the genotype 'yy' (homozygous recessive) and the yellow plants would have the genotype 'YY' (homozygous dominant). When they are crossed, all F1 offspring would have the genotype 'Yy', expressing the dominant yellow phenotype.

For the second generation (F2), when these heterozygous yellow F1 plants (Yy) are crossed with each other, there is a 75 percent chance of having yellow offspring (YY or Yy) and a 25 percent chance of having green offspring (yy), according to Mendelian genetics. This is because each parent can contribute either a 'Y' or a 'y' allele, and the combinations lead to the expected phenotypic ratio of 3 yellow to 1 green seed.