Correct characteristic of class reptilia are

Options

A. Fresh water animals with bony endoskeleton, air bladder to regulate buoyancy
B. Marine animals with cartilaginous endoskeleton, body coverd with placoid scales
C. Body coverd with dry and cornified skin ,scales over body are epidermal, no external ears
D. Body covered with moist skin which is devoid of scales, ear is represented by tympanum, alimentray cancal urinary and reproductive tracts open into a common cloaca.

Answer

To determine the correct characteristics of the class Reptilia, we need to analyze the given options and identify which statements accurately describe reptiles. Here’s a step-by-step breakdown:

### Step 1: Identify the Characteristics of Reptilia
Reptiles are a class of animals that have specific features. Some key characteristics include:
- They are primarily terrestrial.
- They have a dry, cornified skin covered with scales.
- They possess a bony endoskeleton.
- They lay eggs with a leathery shell.
- They do not have external ears.

### Step 2: Analyze Each Option
Now, let’s evaluate the characteristics provided in the question:

1. **Freshwater animals with bony endoskeleton**:
- This statement is incorrect as reptiles can be found in both terrestrial and aquatic environments, and not all are freshwater animals.

2. **Marine animals with cartilaginous endoskeleton body covered with placoid scales**:
- This is also incorrect. While some reptiles (like sea turtles) are marine, reptiles do not have a cartilaginous endoskeleton; they have a bony endoskeleton. Additionally, their scales are not placoid but are epidermal scales.

3. **Body covered with dry and cornified skin**:
- This statement is correct. Reptiles have dry skin that is cornified and covered with scales.

4. **Scales are epidermal**:
- This is also correct. The scales of reptiles are derived from the epidermis.

5. **No external ear is present in reptiles**:
- This statement is correct. Reptiles do not have external ears; they have a tympanum.

6. **Body covered with moist skin**:
- This is incorrect. Reptiles have dry skin, not moist skin.

7. **Devoid of scales**:
- This is incorrect as reptiles have scales.

8. **Ear is represented by tympanum**:
- This is correct. The tympanum serves as the ear in reptiles.

### Step 3: Conclusion
Based on the analysis, the correct characteristics of class Reptilia include:
- Body covered with dry and cornified skin.
- Scales are epidermal.
- No external ear is present in reptiles.

Thus, the correct answer is option number 3.