Final answer:
The percentage of plants producing both round and yellow seeds is 56.25%, however, when only looking at plants producing round seeds, 75% will also produce yellow seeds, matching answer choice d).
Step-by-step explanation:
When two pea plants that are both heterozygous at two gene loci are crossed, where one gene determines seed shape with round seeds (R) being dominant to wrinkled seeds (r), and another gene determines seed color with yellow seeds (Y) being dominant to green seeds (y), the percentage of plants that produce round seeds and also produce yellow seeds can be calculated using the product rule based on independent assortment and dominance.
Since both traits assort independently, the percentage of plants with both round and yellow seeds is found by multiplying the probability of each individual trait being expressed. For seed shape, 3/4 of the offspring are expected to be round (because round is dominant), and similarly, for seed color, 3/4 are expected to be yellow. Thus, the proportion of offspring with both round and yellow seeds is (3/4) × (3/4) = 9/16. When converted to a percentage, this is equivalent to 56.25%, which implies that the correct answer is not directly provided in the options a) 9%, b) 25%, c) 50%, or d) 75%.
If we specifically look at only the plants that produce round seeds, we can ignore the plants with wrinkled seeds and just focus on the round seed offspring. As the cross results in 100% round seeds for this subset, we examine the color proportions within this group. Three-quarters of these round seeds will be yellow and one-quarter green, which means 75% (3/4) of the round-seeded plants will also produce yellow seeds, aligning with answer choice d).