Which of the following ion is pulled out in apoplast by the auxin during growth

Options

A. `K^(+)`
B. `H^(+)`
C. `Na^(+)`
D. `Mg^(2+)`.

Answer

To answer the question "Which of the following ion is pulled out in apoplast by the auxin during growth?", we can follow these steps:

### Step 1: Understand the Role of Auxin
Auxin is a plant growth hormone that promotes cell growth and elongation. It plays a crucial role in various growth processes in plants.

**Hint:** Remember that auxin is primarily involved in promoting growth and elongation in plant cells.

### Step 2: Explore the Mechanism of Auxin Action
Auxin activates proton pumps (H⁺ ATPase) in the plasma membrane of plant cells. This pump uses ATP to transport protons (H⁺ ions) out of the cytoplasm, creating a proton gradient.

**Hint:** Focus on how auxin influences the movement of protons across the cell membrane.

### Step 3: Understand the Concept of Apoplastic Pathway
The apoplastic pathway refers to the movement of water and solutes through the cell walls and intercellular spaces, without crossing the plasma membrane. The acidification of the cell wall due to the action of auxin facilitates this process.

**Hint:** Consider how the movement of ions occurs outside the cell membrane in the apoplast.

### Step 4: Identify the Ion Involved
As auxin activates the proton pumps and creates a proton gradient, this process allows for the uptake of other cations, particularly potassium ions (K⁺), into the cambial and xylem cells.

**Hint:** Think about which ions are typically involved in the transport processes facilitated by auxin.

### Step 5: Conclude the Correct Answer
Based on the information gathered, the ion that is pulled out in the apoplast by the auxin during growth is the potassium ion (K⁺).

**Final Answer:** The correct answer is option 1: Potassium ion.

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