Question

What result Mendel would have got, had he self-pollinated a tall F2 homozygous plant?
A. TT and Tt
B. All Tt
C. All TT
D. All tt

Answer 1

Hint: Self-pollination is the process in which the anther is transferred to the stigma of the same flower which can be genetically identical. Homozygous condition means having identical alleles of a particular gene. Homozygous plants are also known as pure breed.

Complete answer:
Mendel put forward the theory of inheritance which is based upon his cross experiments on the pea plant. He crossed the homozygous tall plant(TT) with the dwarf plant (tt) and obtained the hybrid which was tall (Tt).

The cross can be represented as (TT X tt) the hybrid obtained is Tt and he named it as F1 generation. This hybrid was tall hence he put forward the theory of dominance in which the tall was dominant over dwarf.

In the F2 generation, they cross was made between the hybrids and the offspring obtained in the F2 generation are-
T, t are the gametes formed from the F1 generation hybrid

	T	t
T	TT (tall)	Tt (tall)
t	Tt (tall)	Tt (dwarf)

The three tall plants were obtained out of which two are heterozygous and one is homozygous along with a homozygous recessive. Hence the genotypic ratio of 3:1 was obtained.

According to the question, the self-pollination occurs in the homozygous tall F2 offspring. So, the cross is represented as TT X TT. The offspring obtained are-

	T	T
T	TT	TT
T	TT	TT

We can conclude that all the offspring are homozygous tall. The correct answer is C.

Note: Heterozygous can be defined as the condition in which two different alleles of a particular gene is present. Heterozygous condition leads to formation of hybrids. If the cross was done between the homozygous tall and the hybrid then the result would have been both homozygous tall and heterozygous tall.