Choose the correct option, which explains the term alleles.

The correct answer is Option (1) → The alternative forms of the same gene

In pea, T (tall) and t (dwarf) are the two alleles of the gene for stem height.

Option (1) The alternative forms of the same gene — Correct. Alleles are forms of one gene, coding for a pair of contrasting traits.

Option (2) Sequence of DNA of different genes — Incorrect. Alleles are forms of the same gene, not of different genes.

Option (3) Alphabetical symbols for genes — Incorrect. Letters such as T and t are only the symbols used to write alleles.

Option (4) Dominant and recessive alleles — Incorrect. This names two kinds of allele but does not say what an allele is; it uses the word to define itself.

NCERT Extract:
Inheritance of One Gene – “… Genes which code for a pair of contrasting traits are known as alleles, i.e., they are slightly different forms of the same gene. If we use alphabetical symbols for each gene, then the capital letter is used for the trait expressed at the F1 stage and the small alphabet for the other trait.”