Which of the following is the combination of two different copies of an allele for a gene?

The concept of alleles is fundamental in genetics, where each gene can have different versions known as alleles. When an organism has two different copies of an allele for a given gene, it is described as having a heterozygous genotype. This indicates that one allele may express a dominant trait while the other expresses a recessive trait, leading to potential variations in phenotype.

Heterozygous genotypes play a crucial role in genetics as they contribute to genetic diversity and can influence traits that are expressed in organisms. For instance, in the case of a flower color gene, if one allele codes for red flowers and the other for white flowers, the plant's observable color might depend on which allele is dominant.

On the other hand, the homozygous dominant genotype refers to having two identical dominant alleles for a trait, and the homozygous recessive genotype involves two identical recessive alleles. Heredity, while it pertains to the transmission of genetic characteristics from parents to offspring, does not specifically describe the combination of alleles present in an individual. Understanding the distinction between these terms is essential for grasping concepts in genetics.