Genotype Notation in Genetics

Steps:

• Recognize Tt as standard notation for a heterozygous genotype at a single locus.
• Identify T and t as alleles, which are alternative forms of the same gene.
• Note that the trait (height) is controlled by one gene with two variants present.
• Conclude the organism has one dominant (T) and one recessive (t) allele for height.

Why B is correct:

• Tt represents two distinct alleles (T and t) for the height gene, each a variant form, aligning with Mendelian genetics where alleles are versions of one gene.

Why the others are wrong:

• A: Incorrect, as Tt indicates one gene with two alleles, not multiple genes.
• C: Garbled phrasing; fails to specify two alleles of one gene clearly.
• D: Wrong, as it implies one allele with forms, but alleles are the forms themselves.

Final answer: B