Changeable threshold material in Renal tubules

Options

A. Water and Glucose
B. Urea & Uric acid
C. Glucose & Amino acids
D. Water & salts

Answer

### Step-by-Step Solution:

1. **Understanding the Nephron**: The nephron is the functional unit of the kidney responsible for filtering blood and forming urine. It consists of various parts including the renal corpuscle and renal tubules.

2. **Defining Renal Threshold**: The renal threshold refers to the maximum concentration of a substance in the blood that can be reabsorbed by the renal tubules. If the concentration exceeds this threshold, the excess will be excreted in urine.

3. **Identifying Changeable Threshold Materials**: In the renal tubules, certain substances can be reabsorbed based on their concentration in the blood. These substances are referred to as changeable threshold materials.

4. **Analyzing Options**: The question provides several options regarding which substances are considered changeable threshold materials:
- Water and glucose
- Urea and uric acid
- Glucose and amino acids
- Water and salts

5. **Selecting the Correct Answer**: Among the options, glucose and amino acids are the correct changeable threshold materials. If their concentration in the blood exceeds the renal threshold, they will not be reabsorbed and will instead be excreted in urine.

6. **Conclusion**: Therefore, the changeable threshold materials in renal tubules are glucose and amino acids.