$ Exosmosis causes turgidity.
! Endomosis causes flaccidity.

Options

A. If both As and R are correct and R is correct explanation of As
B. If both As and R are correct but R is not correct explanation of As
C. If As is correct, R is wrong
D. If both As and R are wrong.

Answer

To solve the question regarding exosmosis and endosmosis, we need to analyze both processes and their effects on cell turgidity and flaccidity. Here’s a step-by-step breakdown:

### Step 1: Define Exosmosis
Exosmosis is the process where water or other materials move out of the cell. This typically occurs when a cell is placed in a hypertonic solution, where the concentration of solutes outside the cell is higher than inside.

**Hint:** Remember that "exo-" means "out," indicating that substances are leaving the cell.

### Step 2: Effect of Exosmosis on Cells
When exosmosis occurs, water leaves the cell, causing the cell to lose turgor pressure. As a result, the cell becomes flaccid, which means it is not firm or swollen.

**Hint:** Think of a balloon that is losing air; it becomes limp and loses its shape.

### Step 3: Define Endosmosis
Endosmosis is the process where water enters the cell. This typically happens when a cell is placed in a hypotonic solution, where the concentration of solutes inside the cell is higher than outside.

**Hint:** The prefix "endo-" means "inside," indicating that substances are entering the cell.

### Step 4: Effect of Endosmosis on Cells
When endosmosis occurs, water flows into the cell, causing it to swell and become turgid. Turgidity is important for maintaining the structure and firmness of plant cells.

**Hint:** Imagine a sponge soaking up water; it expands and becomes firm as it absorbs liquid.

### Step 5: Conclusion
Based on the definitions and effects of exosmosis and endosmosis, we can conclude that:
- Exosmosis causes flaccidity (not turgidity).
- Endosmosis causes turgidity (not flaccidity).

Thus, both the assertion and reason provided in the question are incorrect.

**Final Answer:** Both assertion and reason are incorrect.