Chromorsomal disorders are based on

Options

A. mutana allele and their defective products
B. mutant allele and chromosome arrangement
C. mutant allele and imbalance in chromosome number
D. imbalance in chromosome number and chromosome arrangement

Answer

**Step-by-Step Solution:**

1. **Understanding Chromosomal Disorders**: Chromosomal disorders are genetic conditions that arise due to abnormalities in the number or structure of chromosomes. These disorders can lead to various developmental and health issues.

2. **Types of Chromosomal Abnormalities**: There are two main types of chromosomal abnormalities:
- **Aneuploidy**: This refers to an abnormal number of chromosomes. For example, in Down syndrome, there is an extra copy of chromosome 21, leading to a total of 47 chromosomes instead of the normal 46.
- **Structural Abnormalities**: This involves changes in the structure of chromosomes, such as deletions, duplications, inversions, or translocations of chromosome segments.

3. **Identifying the Basis of Chromosomal Disorders**: Chromosomal disorders can be based on:
- **Imbalance in Chromosome Number**: This includes conditions like aneuploidy, where there are too many or too few chromosomes.
- **Chromosome Arrangement**: This includes structural abnormalities that can affect the function of genes located on the chromosomes.

4. **Analyzing the Given Options**: The question provides several options regarding the basis of chromosomal disorders:
- Mutate allele and their defective products
- Mutate allele and chromosomal arrangement
- Mutate allele and imbalance in chromosome number
- Imbalance in chromosome number and chromosome arrangement

5. **Selecting the Correct Option**: Based on the understanding of chromosomal disorders, the correct option is:
- **Imbalance in chromosome number and chromosome arrangement** (Option D). This option accurately reflects the two main bases of chromosomal disorders.

6. **Examples of Chromosomal Disorders**: Examples such as Down syndrome (due to aneuploidy) and Klinefelter syndrome (due to an extra X chromosome in males) illustrate the impact of these chromosomal abnormalities.

**Final Answer**: Chromosomal disorders are based on **imbalance in chromosome number and chromosome arrangement**.

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