Identify the correct statement w.r.t. haemophilia ?

Options

A. It shows criss cross inheritance.
B. It is an autosomal disorder.
C. Single allele produces its effect in both sexes.
D. All of these

Explanation

To identify the correct statement with respect to hemophilia, we can follow these steps:

### Step 1: Understand Hemophilia
Hemophilia is a genetic disorder that affects the blood's ability to clot. This means that individuals with hemophilia can experience excessive bleeding even from minor injuries.

**Hint:** Remember that hemophilia is primarily related to the clotting process in the blood.

### Step 2: Determine the Genetic Basis
Hemophilia is caused by a recessive gene, which means that an individual must inherit two copies of the defective gene (one from each parent) to express the disorder. However, it is important to note that hemophilia is typically linked to the X chromosome.

**Hint:** Focus on the inheritance pattern of hemophilia and how it is passed from parents to offspring.

### Step 3: Recognize the Inheritance Pattern
Hemophilia exhibits criss-cross inheritance. This means that the disorder is often passed from carrier mothers (who have one affected X chromosome) to their sons, while daughters can inherit the affected gene from their fathers.

**Hint:** Criss-cross inheritance is a key characteristic of X-linked recessive disorders.

### Step 4: Evaluate the Given Statements
1. **It shows criss-cross inheritance** - This statement is correct.
2. **It is an autosomal disorder** - This statement is incorrect as hemophilia is X-linked.
3. **Single allele produces its effect in both sexes** - This statement is incorrect because hemophilia primarily affects males, while females can be carriers.

**Hint:** Analyze each statement carefully to determine whether it aligns with the known characteristics of hemophilia.

### Step 5: Identify the Correct Statement
Based on the evaluation, the correct statement regarding hemophilia is that it shows criss-cross inheritance.

**Final Answer:** The correct statement with respect to hemophilia is: **It shows criss-cross inheritance.**