Small chromosomes which do not produce any detectable phenotypic expression are termed

Options

A. Heterochromatic chromosomes
B. Supernumerary chromosomes
C. Nonsense chromosomes
D. Nucleoids

Answer

To answer the question "Small chromosomes which do not produce any detectable phenotypic expression are termed," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**:
- We need to identify small chromosomes that do not lead to any observable traits or phenotypic expressions in organisms.

2. **Defining Phenotypic Expression**:
- Phenotypic expression refers to the observable characteristics or traits of an organism that result from the interaction of its genotype with the environment.

3. **Analyzing Chromosome Types**:
- We need to consider different types of chromosomes and their functions.
- **Heterochromatic Chromosomes**: These are dense regions of DNA that play roles in gene regulation and chromosome integrity. They are associated with detectable functions and thus can affect phenotypic expression.
- **Supernumerary Chromosomes**: These are additional chromosomes that exist alongside the normal set. They do not contribute to the essential functions of the organism and do not produce detectable phenotypic expressions.

4. **Identifying the Correct Answer**:
- Since heterochromatic chromosomes have detectable functions, they cannot be the answer.
- Supernumerary chromosomes, on the other hand, are known to not have any essential functions and do not lead to observable traits in the organism. Therefore, they fit the criteria described in the question.

5. **Conclusion**:
- The answer to the question is **Supernumerary Chromosomes**.

### Final Answer:
Small chromosomes which do not produce any detectable phenotypic expression are termed **Supernumerary Chromosomes**.