Question

Short / Long answer type questions.
Using Mendels monohybrid cross as an example, trace his reasoning to arrive at the law of segregation.

Answer 1

F2 generation	T	t
T	TT (tall)	Tt (tall)
t	Tt (tall)	tt (dwarf)

Monohybrid cross can be studied in the case of the inheritance of plant height. Tall pea plants are dominant over dwarf pea plants. When a tall plant, with genotype TT, is crossed with dwarf pea plant, with genotype tt, the F${}_1$ generation produced are all tall (having genotype Tt).

These plants are self-crossed and F${}_2$ generation so produced is in 1: 2: 1.

From the above observation, we can see that recessive parental trait is expressed without any blending in the F${}_2$ generation. It can be inferred that when the tall and dwarf plants produce gametes, the alleles of the parental pair segregate from each other an=d only one allele is transmitted to the gamete. The segregation is a random process and so there is a 50 percent chance of a gamete containing either allele, in this case, either T or t.