A pea plant with a tall phenotype is pollinated by a short plant, and the seeds

Question

A pea plant with a tall phenotype is pollinated by a short plant, and the seeds of the first generation hybrid produce 327 tall plants and 321 short plants. Give the genotypes of all the plants. In a certain species of plant, one purebred variety has hairy leaves and another pure variety has smooth leaves. A cross of the 2 varieties produces offspring that all have smooth leaves. Predict the ratio of phenotypes in the F2 generation. In fruit flies, straight wings is dominant over curly. Show how you would determine if a straight winged fly were heterozygous or homozygous?

Explanation / Answer

As we have both tall and short plants then the genotype of short will be obviously tt and in genotype of tall plant there muat be a t with T ...only in this condition the offspring can be both short and tall

. So genotype of tall parent plant is Tt and short is tt and genotype of offspring is Tt and tt .

Let genotype for hairy leaves is HH and for smooth leaves it is hh. So f1 will be Hh. In f2 genetation the progeny will be HH and 2Hh and hh .so in this there will be 3 progenies having hairy leaves i.e HHand Hh and there will be 1 progeny having smooth leaves i.e hh

So phenotypic ratio will be 3:1. For hairy to smooth leaves.

We will cross a straight and curly fuit fly and in the progeny if we get all straight winged then the straight winged fly is homozygous and if we also get curly winged then it is heterozygous.

As the pure straight will have genotype SS and pure curly will have ss.

So the progeny for pure will be Ss and for heterozygous it will be Ss and ss. I.e both straight winged and short winged.

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