An example of alleles is:
a. AB and Tt.
b. TT and Tt.
c. T and t.
d. X and Y.
The correct answer and explanation is:
The correct answer is c. T and t.
Explanation:
Alleles are different forms of a gene that exist at a specific locus on a chromosome. In genetics, alleles can be either dominant or recessive. The two alleles for a gene may be the same (homozygous) or different (heterozygous).
The most straightforward example of alleles comes from Mendelian genetics, where different versions of a gene (alleles) determine traits such as height, eye color, or flower color in plants. For instance, in the case of pea plants, the gene for seed shape has two alleles: round (R) and wrinkled (r).
In the given options:
- Option A (AB and Tt): AB represents a blood type, which is not a correct example of alleles in the typical sense. The Tt represents alleles, but AB is not a pair of alleles for a single gene.
- Option B (TT and Tt): Both TT and Tt refer to combinations of alleles, but this is not the ideal way to express just the alleles. TT and Tt refer to the genotypes, not the alleles themselves.
- Option C (T and t): This is the correct example of alleles. “T” and “t” represent different forms of the same gene, where “T” might be the dominant allele (e.g., tall) and “t” the recessive allele (e.g., short). These are classic examples of alleles that can be inherited in a Mendelian fashion.
- Option D (X and Y): X and Y refer to sex chromosomes and not alleles. The X and Y chromosomes determine biological sex, but they are not considered alleles for a specific gene.
Thus, the alleles “T” and “t” are different forms of the same gene, representing the genetic diversity that can exist within an individual organism.