Read the following statements carefully :
(1) Gap junction facilitates the cells to communicate with each other by connecting the cytoplasm of two adjoining cells to cytoplasm of two adjoining cells .
(2) Adhering junctions help to stop substances from leaking across a tissue .
(3) compound epithelium covers the dry surface of the skin only and provides protection against chemical and mechanical stresses.
(4) most of the bones in vertebrates embryos are replaced by cartilages in adults.
How many of the above statement is/are correct ?

Options

A. Four
B. Three
C. One
D. Two

Answer

To determine how many of the provided statements are correct, let's analyze each statement one by one:

### Step 1: Analyze Statement 1
**Statement 1:** "Gap junction facilitates the cells to communicate with each other by connecting the cytoplasm of two adjoining cells."

- **Analysis:** This statement is correct. Gap junctions are specialized intercellular connections that allow direct communication between adjacent cells by connecting their cytoplasm. This enables the transfer of ions and small molecules, facilitating cell communication.

### Step 2: Analyze Statement 2
**Statement 2:** "Adhering junctions help to stop substances from leaking across a tissue."

- **Analysis:** This statement is incorrect. The junctions that prevent leakage of substances across tissues are called tight junctions, not adhering junctions. Adhering junctions (or desmosomes) provide mechanical stability and support between cells but do not primarily function to prevent leakage.

### Step 3: Analyze Statement 3
**Statement 3:** "Compound epithelium covers the dry surface of the skin only and provides protection against chemical and mechanical stresses."

- **Analysis:** This statement is also incorrect. While compound epithelium does provide protection, it is not limited to the dry surface of the skin. It can also be found in other areas, such as the inner lining of the mouth and esophagus. Thus, it is not accurate to say it covers only the skin.

### Step 4: Analyze Statement 4
**Statement 4:** "Most of the bones in vertebrates embryos are replaced by cartilages in adults."

- **Analysis:** This statement is incorrect. In vertebrate embryos, the initial skeletal structure is primarily cartilaginous, which is later replaced by bone during development. Therefore, it is not accurate to say that bones are replaced by cartilages in adults; rather, cartilaginous structures are replaced by bony structures.

### Conclusion
After analyzing all four statements:
- Statement 1 is correct.
- Statements 2, 3, and 4 are incorrect.

Thus, the total number of correct statements is **1**.

### Final Answer
**Only 1 statement is correct.**

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