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I read in my book that "two alleles are considered to be homozygous if they are identical". But at the same time I read the definition of allele to be:
genes which code for a pair of contrasting traits are called alleles
My doubt is that how can they be both contrasting (different) and identical (same) at the same time
What I think is that if homozygous is somehow a part of specific conditions in alleles then how can it be different from alleles itself.
These are just issues with singular and plural and whether you refer to individual copies or categories/types.
Two of the same allele copies are the same allele (category/type). Two different alleles (copies) can also be different (categories/types).
In the context of a diploid individual, they have two instances of each gene so therefore two alleles; these alleles can be the same or different.
So you can say you have two "red flower" alleles, meaning two copies of the red flower allele. Or you can have a population that has two alleles for flower color: red flower alleles or white flower alleles.
The same is used in English for other things. You might say a farm grows two fruits, peaches and plums, and also that I have two fruits in my hand, both peaches. You need to use surrounding context to recognize whether copy or type is meant.
