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5
In
tomatoes, the allele for red fruit, R, is dominant to that for yellow
fruit, r. The allele
for tall
plant, T, is dominant to that for short plant. t. The two genes concerned
are on
different
chromosomes. (a)
A tomato
plant is homozygous for allele R. Giving a reason for your answer in
each
case, how many copies of this allele would be found in (i)
a male
gamete produced by this plant,
(ii)
a leaf
cell from this plant?
(b)
A cross
was made between two tomato plants.
(i)
The
possible genotypes of the gametes of the plant chosen as the male
parent
were RT, Rt, rT and rt. What was the
genotype of this plant? (ii)
The
possible genotypes of the gametes of the plant chosen as the female
parent
were rt and rT. What was the
phenotype of this plant? (iii)
What
proportion of the offspring of this cross would you expect to have
red
fruit?
Use a genetic diagram to explain your answer.
(2) (1) |