Question

What is the meaning of single pair of alleles ??

Answer 1

this seems to be solved witha simple google search. good luck learning how to use the internet.

Answer 2

ALLELES are different forms of the same gene.
They come together to form GENOTYPES. Yes, GENOTYPES are made of ALLELES.
And when we're talking about alleles, we can represent them using letters.

For example,
pretend we're talking about different heights of pea plants.

A TALL pea plant might have the genotype (T t).

Look at that genotype. (T t).
There are TWO alleles in this genotype, you see?
(T) and (t).

A pair of alleles is just two of these letters, put together.