Alleles are:

Options

A. Homologous chromosomes
B. Linked genes
C. Dominant genes
D. Alternate forms of a gene

Answer

**Step-by-Step Solution:**

1. **Understanding the Concept of Alleles:**
- Alleles are different forms of a gene that can exist at a specific locus on a chromosome. Each gene can have multiple alleles, which contribute to the genetic diversity within a population.

2. **Identifying the Options:**
- The question provides four options to choose from:
a) Homologous chromosomes
b) Length gene
c) Dominant gene
d) Alternate forms of gene

3. **Analyzing Each Option:**
- **Homologous chromosomes:** These are pairs of chromosomes, one from each parent, that are similar in shape, size, and genetic content. This option does not define alleles.
- **Length gene:** This term is not commonly used in genetics and does not accurately describe alleles.
- **Dominant gene:** This refers to a gene that can mask the expression of another gene (recessive). While related to alleles, it does not define what alleles are.
- **Alternate forms of gene:** This option accurately describes alleles, as they are indeed different forms or variants of a gene.

4. **Selecting the Correct Answer:**
- Based on the analysis, the correct answer is **d) Alternate forms of gene**.

5. **Conclusion:**
- Alleles are best defined as alternate forms of a gene, which can lead to variations in traits among individuals.

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