Question

Alleles are

• A. different molecular forms of a gene
• B. heterozygotes
• C. different phenotype
• D. true breeding homozygotes

Answer 1

The Correct Option is A

The question is about understanding the concept of alleles in genetics. Let's break it down step-by-step: 

1. The term "alleles" refers to the different versions or forms of the same gene. They can vary slightly in their sequence of DNA bases, leading to variations in phenotype associated with the gene.
2. Each organism inherits two alleles for each gene—one from each parent. These alleles can be the same or different, leading to different genetic combinations.
3. The list of options given in the question allows us to identify which definition pertains to alleles:
   • Different molecular forms of a gene: This option correctly describes what alleles are, as they are essentially different versions of the same gene.
   • Heterozygotes: This term refers to an individual having two different alleles for a particular gene. Although related to alleles, it defines the genetic condition, not the alleles themselves.
   • Different phenotype: While alleles may lead to different phenotypes (observable traits), this option defines the result of alleles rather than alleles themselves.
   • True breeding homozygotes: This term refers to individuals having two identical alleles for a gene, which again describes a condition relating to alleles but not the definition of alleles.
4. Based on the above analysis, the correct answer is: Different molecular forms of a gene.
5. This understanding is crucial in genetics as it forms the basis of variation seen in individuals of the same species, influencing a wide range of traits from eye color to risk of hereditary diseases.