In born error of metabolism discovered in humans by Sir Archibald Garrod is

Options

A. Alkaptonuria
B. phenylketonuria
C. ketonuria
D. sickle cell anaemia

Answer

**Step-by-Step Solution:**

1. **Understanding Inborn Errors of Metabolism**: Inborn errors of metabolism are genetic disorders that result from the deficiency of a specific enzyme, leading to the accumulation of toxic substances in the body or the inability to produce essential substances.

2. **Identifying the Discoverer**: Sir Archibald Garrod was a pioneer in the study of inborn errors of metabolism. He was the first to suggest that certain diseases were caused by genetic defects affecting metabolic pathways.

3. **Recognizing the Specific Disorder**: The specific inborn error of metabolism discovered by Sir Archibald Garrod in humans is known as "Alkaptonuria."

4. **Understanding Alkaptonuria**: Alkaptonuria, also referred to as "Black Urine Disease," is a condition where the body cannot completely break down two amino acids, tyrosine and phenylalanine. This leads to the accumulation of homogentisic acid, which, when excreted in urine, causes the urine to turn dark upon exposure to air.

5. **Evaluating Other Options**:
- **Phenylketonuria (PKU)**: This is a different metabolic disorder caused by a deficiency in the enzyme that breaks down phenylalanine.
- **Ketoneuria**: This condition involves the presence of ketones in the urine, often associated with diabetes or starvation, and is not related to Garrod's work.
- **Sickle Cell Anemia**: This is a genetic disorder affecting hemoglobin in red blood cells and is unrelated to metabolic pathways involving amino acids.

6. **Conclusion**: The correct answer to the question is Alkaptonuria, as it is the inborn error of metabolism discovered by Sir Archibald Garrod.

**Final Answer**: Alkaptonuria (Black Urine Disease)

---