Question

Genes related to one character has two constract traits. But only one among them is considered as dominant. How?

Answer 1

for finding the trait which show dominant character/ which show their effect in the first generation.

I hope it will help u

Answer 2

Genes related to one character has two constract traits. But only one among them is considered as dominant this is because, the trait which is more effective than the other will suppress the activity of the recessive trait and will express itself in the F1 generation.  

Explanation:

For example the gene coding for trait height of the pea plant is considered as:

Dominant: Tall (T)

Recessive: Dwarf (t)

F1 generation: Tt (Tall as the dominant gene express itself completely than the recessive one)