2002 AIPMT Principles of Inheritance and VariationMendel's Law of Dominance Easy Question 2 of 2 in Mendel's Law of Dominance

A gene is said to be dominant if : -

A It expresses its effect only in homozygous stage
B It is expressed only in heterozygous condition
C It is expressed both in homozygous and heterozygous condition
D It is never expressed in any condition

The answer is C.

Solution

A dominant allele expresses its character whether it is present in two copies (homozygous, TT) or in one copy along with a recessive allele (heterozygous, Tt).
For example, tall (T) in pea: both TT and Tt plants are tall.
A recessive allele, in contrast, is expressed only in the homozygous condition (tt).
So a gene is said to be dominant if it is expressed both in the homozygous and the heterozygous condition.

Concept Expression of a dominant allele

Mendel's Law of Dominance in past papers

2 questions from this chapter have appeared across 2 exam years.