Respuesta :
d) AA;BB;cc;dd genotypes will be rarest to observe among the progeny.
Explanation:
Let us cross the given alleles of the gene
Aa X AA Bb X Bb Cc X cc Dd X Dd
A a B b C c D d
A AA Aa B BB Bb c Cc cc D DD Dd
A AA Aa b Bb bb c Cc cc d Dd dd
From the above results of crosses, it can be concluded which of the genotypes is rarest among the progeny. The genotype ratios in:
In the first case it can be both as they are in the ratio of 2:2
In the second case 1:2:1
in the third case 2:2
in the fourth case 1:2:1
So least occurring genotypes are
AA;BB;cc;dd
AA;BB;cc;dd genotypes will be the rarest to observe among the progeny
d. AA;BB;cc;dd
Explanation:
AaBbCcDd X AABbccDd
Aa X AA - AA, AA, Aa, Aa - Genotypic ratio = 1:1
Bb X Bb - BB, Bb, Bb, bb - Genotypic ratio = 1:2:1
Cc X cc - Cc, Cc, cc, cc - Genotypic ratio = 1:1
Dd X Dd - DD, Dd, Dd, dd - Genotypic ratio = 1:2:1
We can see that the heterozygous combinations occur more in number.
Whereas, Homozygous recessive appears the least.
Therefore, the rarest to observe among the proge is AABBccdd as is has two recessive combination.
