For a particular plant, red flowers (A) are dominant over yellow flowers (a). An initial cross was made between a plant that was true-breeding for red flowers and another plant true-breeding for yellow flowers. F1 progeny, all having red flowers, were allowed to self- pollinate and form seeds, which were then planted to generate F2 progeny. Pollen from all the resulting F2 plants was pooled and used to fertilize true-breeding yellow plants. What proportion of the progeny resulting from this cross would be expected to have yellow flowers

The correct answer would be - 1 out of 4 or 25% offspring would be expected to have yellow flowers

Explanation:

Red flowers are dominant over the yellow flower, initially, a cross was made between true-breeding red and true-breeding of yellow flowers

Red flower plant gametes, a  and a and red plants gamete would be  A and A.

so,

       A          A

a     Aa         Aa

a      Aa        Aa

in this cross, all the offspring are red as they have a heterozygous genotype. Now self-pollinating these F1 generation offsprings, gametes would be A and a for both parents:

       A        a

A     AA     Aa

a      Aa     aa

in the f2 generation, there is only 25% of offsprings are yellow flowers.