Keeping the guard cells turgid requires a continuous supply of both .................. ions and ...............

Explanation

To answer the question "Keeping the guard cells turgid requires a continuous supply of both .................. ions and ...............", we can break down the solution into the following steps:

### Step 1: Understand the Role of Guard Cells
Guard cells are specialized cells that surround the stomata (small openings on the surface of leaves) and are responsible for regulating their opening and closing. Their turgidity (swollen state) is crucial for this function.

**Hint:** Think about what processes are involved in the opening and closing of stomata.

### Step 2: Identify What Causes Turgidity
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