What fraction of the offspring of the cross aabb × aabb would show the dominant phenotypes for both genes?

None.

Explanation:

Mendel has been known as the father of genetics. He has explained the laws of genetics including the concept of dominance, law of segregation and law of independent assortment.

The dominant phenotype is represented by the upper case letters and the recessive phenotype is represented by the same lower case letters. The cross include the aabb ×  aabb.

Parents   aabb ×  aabb.

Gametes       ab.

Offspring         aabb.

No dominant phenotype for both the genes will be obtained as this case includes the cross between the recessive phenotypes.

Thus, the answer will be none fraction.

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