Land reptiles like lizards and snakes excrete

Options

A. Ammonia
B. Urea
C. Amino acid
D. Uric acid

Answer

To answer the question "Land reptiles like lizards and snakes excrete," we need to understand the types of nitrogenous waste excretion in different organisms. Here’s a step-by-step solution:

### Step 1: Understand the Types of Nitrogenous Waste
Organisms excrete nitrogenous waste primarily in three forms: ammonia, urea, and uric acid. Each type is associated with different groups of animals based on their habitat and physiology.

### Step 2: Identify the Excretion Method of Aquatic Animals
- **Ammonia**: This is the most toxic form of nitrogenous waste. Aquatic animals, such as many fish, excrete ammonia directly into the water where it can be diluted. This method requires a large amount of water for excretion.

### Step 3: Identify the Excretion Method of Terrestrial Animals
- **Urea**: This is less toxic than ammonia and is excreted by mammals and some amphibians. The conversion of ammonia to urea occurs in the liver through the urea cycle. Urea requires less water for excretion compared to ammonia.

### Step 4: Identify the Excretion Method of Reptiles
- **Uric Acid**: This is the least toxic form of nitrogenous waste and is excreted by reptiles, birds, and some insects. Uric acid is excreted as a semi-solid paste, which conserves water, making it advantageous for land-dwelling organisms that may not have constant access to water.

### Step 5: Analyze the Options Given
The options provided are:
1. Ammonia
2. Urea
3. Amino acid
4. Uric acid

From our understanding:
- Ammonia is primarily excreted by aquatic organisms.
- Urea is excreted by mammals.
- Amino acids are not a common form of excretion for most animals.
- Uric acid is excreted by reptiles, including lizards and snakes.

### Conclusion
Based on the analysis, the correct answer is that land reptiles like lizards and snakes excrete **uric acid**.

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