What is the difference between homozygous and heterozygous genes?

• A. Homozygous genes result in a blend of traits, while heterozygous genes result in a single trait expression.
• B. Homozygous genes are always dominant, while heterozygous genes are always recessive.
• C. Homozygous genes are found only in plants, while heterozygous genes are found only in animals.
• D. Homozygous genes have identical alleles, while heterozygous genes have different alleles.

Answer: (D)

Verified step by step guidance

1. Understand the basic concept of alleles: Alleles are different forms of a gene that are found at the same place on a chromosome. They can be dominant or recessive.
2. Define homozygous: An organism is homozygous for a gene if it has two identical alleles for that gene. This can be either two dominant alleles (AA) or two recessive alleles (aa).
3. Define heterozygous: An organism is heterozygous for a gene if it has two different alleles for that gene, one dominant and one recessive (Aa).
4. Clarify the expression of traits: In homozygous individuals, the trait expressed is determined by the identical alleles. In heterozygous individuals, the dominant allele typically masks the expression of the recessive allele, resulting in the expression of the dominant trait.
5. Summarize the key difference: The main difference between homozygous and heterozygous genes is that homozygous genes have identical alleles, while heterozygous genes have different alleles.