Final answer:
The different variants of a trait available to a gene are called alleles. These represent different versions of a gene and determine an organism's genotype, which in turn affects their phenotype. Polygenic traits involve multiple genes and alleles, contributing to a wide range of observable characteristics. The correct answer is c.Genotypes
Step-by-step explanation:
The different variants of a trait available to a gene are called alleles. Alleles are essentially different versions of the same gene, providing diversity in the physical traits or characteristics that they encode. For instance, in humans, the ABO blood type is determined by three different alleles (A, B, O), which produce the various blood types observed in the population. An individual's specific combination of alleles—known as their genotype—determines their observable characteristics, or phenotype.
When it comes to polygenic traits, such as height or skin color, these traits are influenced by multiple genes, leading to a wide range of possible phenotypes. In contrast, characteristics like the sickle-cell trait are controlled by a single gene. Alleles can be either dominant or recessive, which affects whether they are expressed in an organism's phenotype. Dominant alleles will express the trait even if only one copy is present, while recessive alleles require two copies for the trait to be expressed.
Inheritance patterns of alleles were first outlined by the work of Gregor Mendel, and further understanding of allele distribution in populations is explored through the field of population genetics. This area of study examines how selective forces and genetic diversity impact the frequencies of alleles and genotypes within a population over time.