An organism with identical allelic genes is described as

Step 1: Analyze the question The question asks for the term used for an organism whose two alleles for a gene are identical.

Step 2: Explain the concept Alleles are alternative forms of a gene found at the same locus on homologous chromosomes. An organism inherits one allele from each parent, so the two alleles can be:

• Identical (e.g., TT or tt), which is homozygous
• Different (e.g., Tt), which is heterozygous

Step 3: Check each option

• A. Dihybrid: This describes a cross, or an offspring, involving two different gene pairs (e.g., AaBb). It is not about identical alleles.
• B. Heterozygous: The alleles are different (Tt), so this is the opposite of the answer.
• C. Homozygous: Both alleles are the same (TT or tt). This fits.
• D. Monohybrid: This describes a cross involving one gene pair (e.g., Tt × Tt). It is not about identical alleles.
• E. Recessive: This describes an allele that is only expressed when it is present in two copies. It does not describe the genotype as a whole.

Step 4: Answer An organism with identical allelic genes is homozygous.

Exam tip: "Homo" means same and "hetero" means different. So homozygous means "same zygote genes", and heterozygous means "different genes". Also note that the homozygous dominant genotype (TT) and the homozygous recessive genotype (tt) are both homozygous.