Normal chlorophyll development in plants requires the

presenceof at least one dominant allele at gene A and at least one

dominantallele at gene B. Double homozygous recessive plants (a b /

ab) lack chlorophyll and are white. The two genes are on thesame

chromosome and recombine with a frequency of 5% (i. e., r = 5%ir

0.05). From the cross of A B / a b x A B / a b, what's the expected

frequency of white plants among theprogeny?

about 6%

Explanation:

From AB / ab we can obtain the AB, Ab, aB and ab gametes.

With the Punnett square we can obtain:

AB Ab aB ab

AB AABB AABb AaBB AaBb

Ab AABb AAbb AaBb Aabb

aB AaBB AaBb aaBB aaBb

ab AaBb Aabb aaBb aabb

As the normal development of chlorophyll in plants requires the presence of at least one dominant allele in gene A and at least one dominant in gene B, only double homozygous aabb genotype lacks chlorophyll and the plant has white phenotypes.