Question

The genotype of green stemmed tomato plants is denoted as gg and that of purple stemmed tomato plants is denoted as gg. when these two are crossed with each other: (3) (a) what colour of stem would you expect in the f1 progeny? (b) give the percentage of purple stemmed plants if f1 plants are self-pollinated.

Answer 1

The genotype of green stemmed tomato plant is denoted as GG and genotype of purple stemmed tomato plant is denoted as gg.
a. The colour of the stem would be green in the first generation .Because G is a dominated trait while g is a
recessive trait.
b. In the second generation one forth of the plants have a purple stem .so there would be 25% of purple stemmed plants in f2 generation.

Answer 2

The genotype of green stemmed tomato plant is GG and the genotype of purple stemmed tomato plant is gg.

A. When we cross them to produce progeny in the F1 generation, we will find that all the plants have green stems ( this shows us that green coloured stem is dominant) .

B. When we get the F2 generation to reproduce by self pollination we will now find that about 1/4th of the progeny will have purple stems and the remaining 3/4th will be green stemmed.

In other 25% of the progeny in the F2 generation are found to have purple stems.

So we can conclude that since having purple stems is a recessive trait , plants can have purple stems if and only if they are in the pure form(ie. gg ) .