What is true for colour blindness and haemophilia ?

Options

A. Nutritional deficiency disorders
B. X-linked recessive disorders
C. Autosomal recessive disorders
D. autosomal dominant disorders

Explanation

**Step-by-Step Solution:**

1. **Identify the Disorders**: The question asks about color blindness and hemophilia. Both are genetic disorders that affect individuals differently.

2. **Understand Color Blindness**: Color blindness primarily affects the ability to differentiate between colors, most commonly red and green. It can be classified into types based on the specific colors affected.

3. **Understand Hemophilia**: Hemophilia is a genetic disorder that affects the blood's ability to clot. Individuals with hemophilia can suffer from excessive bleeding, even from minor injuries, due to a deficiency in clotting factors.

4. **Determine the Genetic Basis**: Both color blindness and hemophilia are linked to genes located on the X chromosome. This means they are X-linked disorders.

5. **Genetic Representation**:
- For color blindness:
- A color blind female is represented as XcXc (homozygous recessive).
- A color blind male is represented as XcY (hemizygous).
- For hemophilia:
- A hemophilic female is represented as XhXh.
- A hemophilic male is represented as XhY.

6. **Carrier Status**:
- Females can be carriers for these disorders if they have one normal and one affected X chromosome (e.g., XcX or XhX). They do not exhibit symptoms but can pass the disorder to their offspring.

7. **Conclusion**: The key point is that both color blindness and hemophilia are X-linked recessive disorders, meaning the genes responsible for these conditions are located on the X chromosome and require two copies of the recessive allele for females to express the disorder, while males only need one copy.

**Final Answer**: Color blindness and hemophilia are both X-linked recessive disorders.

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