If two parents that are heterozygous (Aa) at a single locus give rise to offspring that are 25 percent AA, 50 percent Aa, and 25 percent aa, then all of the following are true EXCEPT:

A. The parents are diploid organisms.
B. The a allele is recessive lethal.
C. The alleles assort independently.
D. The gametes combine at random.
E. The probability that a given gamete will receive allele A is one-half.

I don't understand your question

Answered by emmanuelvenkatsami | 2024-06-10

The incorrect statement is (B) The a allele is recessive lethal, as this would impact the expected 25 percent aa offspring. The correct statements reflect the 1:2:1 genotypic ratio from a heterozygous monohybrid cross.

The question concerns Mendelian genetics and independent assortment of alleles during gamete formation. If two parents that are heterozygous (Aa) at a single locus give rise to offspring that are 25 percent AA, 50 percent Aa, and 25 percent aa, then all of the following are true EXCEPT: (B) The a allele is recessive lethal. This is incorrect because a recessive lethal allele would not allow aa individuals to survive, thereby reducing or eliminating the 25 percent aa offspring. Instead, this scenario demonstrates the typical 1:2:1 genotypic ratio resulting from a monohybrid cross between two heterozygous individuals, where the alleles assort independently, and gametes combine at random. Also, the probability of a gamete receiving allele A is indeed one-half, as each parent is heterozygous Aa.

Answered by NeelamY | 2024-06-25

The incorrect statement is (B) that the a allele is recessive lethal, because having aa offspring indicates it is not lethal. All other statements regarding the parents being diploid, the independent assortment of alleles, random combination of gametes, and the probability of receiving allele A being one-half are true.
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Answered by NeelamY | 2024-12-23