Question

Use a Punnett square to predict the offspring in a cross between a dwarf pea plant—homozygous recessive—and a tall pea plant—heterozygous. What is the phenotypic ratio of the offspring?
a) 1 tall:1 dwarf
b) 1 tall:2 dwarf
c) 3 tall:1 dwarf
d) 1 dwarf:4 tall

Answer 1

Answer:

a) 1 tall:1 dwarf

Explanation:

Let's assume that the allele T is responsible for tallness while the allele "t" imparts dwarfism. The genotype of a homozygous recessive dwarf pea plant is "tt" and that of the heterozygous tall pea plant is "Tt". The heterozygous tall parent would make two types of gametes in equal proportion while the homozygous parent would produce all the gametes carrying "t" allele only.

A cross between Tt and tt gives progeny in following phenotype ratio= 1 tall: 1 dwarf.