Question

Describe the cross between a homozygous tall, round-seeded pea plant and a dwarf, wrinkled-seeded pea plant. What will be the types of progeny in the F₂ generation of this cross and in what proportion will it be? Name and state the law which is explained by this example.

Answer 1

Let the gene for tall habit of pea plant be represented by ‘T’ and dwarf habit be represented by ‘t’.

Let the gene for round-seed be represented by ‘R’ and that of wrinkled seed be represented by gene ‘r’.

Then, the genotypes of the parents would be:

i. Homozygous tall, round-seeded – TTRR

ii. Homozygous dwarf, wrinkled seeded – ttrr

The above example of a dihybrid cross between homozygous tall, round-seeded pea plant and dwarf, wrinkled-seeded pea plant explains the ‘Law of Independent Assortment’.

The law of independent assortment states that “when two parents differing from each other in two or more pairs of contrasting characters are crossed, then the inheritance of one pair of character is independent of the other pair of character.”