Genes which code for a pair of contrasting traits are known as

Options

A. dominant genes
B. alleles
C. linked genes
D. none of these

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question:**
The question asks for the term used to describe genes that code for a pair of contrasting traits. This implies that we are looking for a specific type of gene that can exist in different forms.

**Hint:** Think about the different forms a gene can take that lead to variations in traits.

2. **Identifying Key Terms:**
In genetics, the term "allele" refers to the different forms of a gene that can exist at a specific locus on a chromosome. For example, a gene that determines height can have alleles for tallness (T) and dwarfism (t).

**Hint:** Recall the definition of alleles and how they relate to traits.

3. **Contrasting Traits:**
The question mentions "contrasting traits." This is a key characteristic of alleles, as they represent different expressions of the same gene. For instance, the trait for flower color can be red or white, which are contrasting traits controlled by different alleles.

**Hint:** Consider how alleles can lead to different observable characteristics in organisms.

4. **Dominant and Recessive Alleles:**
Within the context of alleles, some can be dominant (expressed when present) while others can be recessive (only expressed when two copies are present). For example, in the case of height, the tall allele (T) is dominant over the dwarf allele (t).

**Hint:** Think about how dominant and recessive traits interact and what that means for the expression of traits.

5. **Conclusion:**
Based on the understanding that alleles are the alternative forms of a gene that code for contrasting traits, we conclude that the answer to the question is "alleles."

**Final Answer:** Genes which code for a pair of contrasting traits are known as **alleles**.

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