Question

A garden pea plant produced round, green seeds. Another of the same species produced wrinkled, yellow seeds. Identify the dominant traits.

Answer 1

Hint: Traits (or character state) are the distinct variants of the phenotypic characteristics of organisms. Traits expressed by the organisms depend either on the genetics or the environmental factors around it; but it is mostly a combination of both.

Complete Answer:
The garden pea plant, scientifically known as Pisum sativum, was the primary plant species studied by Gregor Mendel, also called the ‘Father of Genetics’. Pea plants were studied by Mendel to arrive at conclusion regarding the inheritance of traits from one generation to the other. It was observed that pea plants had characteristic evident phenotypic traits with easily comprehensible inheritance patterns.
These traits are:

1.	Pea shape	Round [D]	Wrinkled [R]
2.	Pea color	Green [R]	Yellow [D]
3.	Pod shape	Constricted [R]	Inflated [D]
4.	Pod color	Green [D]	Yellow [R]
5.	Flower color	Purple [D]	White [R]
6.	Plant size	Tall [D]	Dwarf [R]
7.	Position of flowers	Axial [D]	Terminal [R]

- A significant observation of Mendel’s research was that for each trait of the pea plant, the one which was expressed at most times was dominant over the other recessive trait; the same is mentioned in the list above as D=Dominant & R=Recessive in brackets next to each trait.
- From the list above, it is evident that the round seed shape is dominant over wrinkled seed shape whereas yellow seed color is dominant over green seed color.
- Thus, in a pea plant producing round, green seeds and another producing wrinkled, yellow seeds, round seed shape and yellow seed color are dominant characters.

Note: In some organisms, the alleles of a particular trait (gene) are not exactly dominant or recessive compared to each other. As a result, the offspring heterozygous for that trait expresses the characteristics of both the alleles together and thus their phenotype is a combination of both these alleles. This is known as codominance.