Question

You work with a variety of apples that are red. Over the years, you've seen some variants (mutants) show up among your plants, and decide to investigate this matter further. You come up with two true-breeding variants, one that gives yellow apples, and one that gives orange apples. Through a series of monohybrid crosses, you establish that both are caused by recessive alleles. And now you decide to see how those genes interact between them (if at all). But first things first - you decide to determine if the alleles complement. You suspect that they will, because each gives you a different phenotype... but geneticists have seen some really weird things, trust me. So you set up a cross between yellow-apple and orange-apple trees. If the alleles complement, then you expect 100% of the progeny to have red fruit. And yet... 50% of the progeny shows up with red fruit, and 50% of the progeny has yellow apples. In 200 words or fewer, entertain an explanation of what may have happened here (i.e. formulate a hypothesis). Make sure to defend your hypothesis with a clear explanation of why it would explained the observed results.

Answer 1

Recessive alleles show their effect only when two copies of the same allele is present (i.e. homozygous condition is there). on the other hand, complementation occurs only when two strains of an organism with two different homozygous recessive mutations that produce the same mutant phenotype produce offspring with wild-type phenotype when mated or crossed. According to the mendel's hypothesis: Monohybrid cross is a cross between two pure organisms in order to study the inheritance of a single pair of alleles. In this the test cross ratio is 1:1.

The above hypothesis is also same as Mendels hypothesis: Here the cross is between yellow apple and orange apple. In the monohybrid cross the ratio of offsprings observed is 50:50 in mendels hypothesis results which can be proved here also from the above result. The result is 50 % yellow apple and 50 % red apple. Since the alleles are not complement the progeny is not expected to have 100 % of yellow apples which is otherwise dominant.

Therefore, the hypothesis is proved from the mendels results of the monohybrid cross. In both the cases the progeny contains 50 % of both.