Mark correct option w.r.t multiple allels.

Options

A. Show crossing over between them
B. Are always codominants
C. Affect different characters
D. Are found in population

Answer

### Step-by-Step Solution:

1. **Understanding Multiple Alleles**:
- Multiple alleles refer to the presence of more than two alleles for a single gene within a population. Unlike Mendel's law of dominance which states that a gene can have only two alleles (one dominant and one recessive), multiple alleles allow for a greater variety of genetic combinations.

2. **Example of Multiple Alleles**:
- The ABO blood group system in humans is a classic example of multiple alleles. It is controlled by three alleles: IA (which produces A antigen), IB (which produces B antigen), and i (which produces no antigen, resulting in type O blood).

3. **Analyzing the Options**:
- **Option A**: "We will get crossing over between them."
- This is incorrect because crossing over occurs between homologous chromosomes, not within a single gene's multiple alleles.

- **Option B**: "They are always co-dominant."
- This is also incorrect. While IA and IB are co-dominant in the ABO system, not all multiple alleles exhibit co-dominance. Some may show complete dominance or incomplete dominance.

- **Option C**: "It affects different characters."
- This statement is wrong as well. Multiple alleles refer to variations of a single gene affecting the same trait, not different traits.

- **Option D**: "Multiple alleles are found in the population."
- This is the correct option. Multiple alleles exist within a population, allowing for genetic diversity among individuals. Each individual can only possess two alleles (one from each parent), but the population can have many variations.

4. **Conclusion**:
- The correct answer to the question regarding multiple alleles is **Option D**: "Multiple alleles are found in the population."