A diploid organism that has two identical alleles for the same trait is called for that particular trait. Explain briefly and select one
A. Homozygous.
B. heterozygous.
C. dominant.
D. codominant.
The correct answer and explanation is :
The correct answer is A. Homozygous.
Explanation:
In genetics, a diploid organism carries two copies of each gene, one inherited from each parent. These two copies of a gene can either be identical or different. The terms homozygous and heterozygous are used to describe these situations.
- Homozygous refers to the condition where both alleles of a gene are identical. For example, if an organism has two copies of the same allele (like two “AA” or two “aa” alleles), it is considered homozygous for that trait.
- Heterozygous, on the other hand, refers to when the two alleles for a gene are different. For example, if an organism has one “A” allele and one “a” allele (Aa), it is considered heterozygous.
To illustrate this further:
- An individual with a homozygous genotype for a gene might have two dominant alleles (e.g., “AA”) or two recessive alleles (e.g., “aa”).
- In contrast, a heterozygous individual will have one dominant and one recessive allele (e.g., “Aa”).
The terms dominant and codominant refer to how alleles interact with each other:
- A dominant allele is one that expresses its trait even if only one copy is present (e.g., “A” in “Aa”).
- Codominant alleles both contribute to the phenotype when present, meaning both alleles are expressed equally (e.g., in certain blood types, such as AB blood type, where both A and B alleles are expressed).
Thus, for the question asked, the correct term describing an organism with two identical alleles for a trait is homozygous.