The passive movement of mineral ions into the apoplast occurs

Options

A. at a rapid pace selectively through ion-channels
B. at the expenditure of metabolic energy
C. at a slow pace freely through the ion-channels
D. independently of the gradient

Answer

To solve the question regarding the passive movement of mineral ions into the apoplast, we can break it down into the following steps:

### Step 1: Understand the Apoplast
The apoplast refers to the network of cell walls and intercellular spaces in plants, allowing for the movement of water and solutes. It is one of the pathways through which substances can move in plant tissues.

**Hint:** The apoplast is a pathway in plants that includes cell walls and spaces between cells.

### Step 2: Define Passive Movement
Passive movement refers to the transport of substances across cell membranes without the expenditure of energy. This occurs along the concentration gradient, meaning substances move from areas of higher concentration to areas of lower concentration.

**Hint:** Passive movement does not require energy; it relies on concentration gradients.

### Step 3: Identify the Mechanism of Ion Movement
In the context of mineral ions moving into the apoplast, this process occurs rapidly through specific channels known as ion channels. These channels facilitate the selective uptake of ions without the need for energy.

**Hint:** Ion channels are proteins that allow specific ions to pass through the cell membrane.

### Step 4: Evaluate the Options
1. **At a rapid pace selectively through the ion channel** - This option aligns with the definition of passive movement as it describes the rapid and selective uptake of ions through channels.
2. **Expenditure of metabolic energy** - This option is incorrect as passive movement does not require energy.
3. **At a slow pace freely** - This option does not accurately describe the mechanism of ion movement into the apoplast, as it suggests a slow and unrestricted flow, which is not characteristic of the selective ion channels.

**Hint:** Evaluate each option based on the definitions of passive movement and the characteristics of the apoplast.

### Step 5: Conclusion
Based on the analysis, the correct answer is that the passive movement of mineral ions into the apoplast occurs at a rapid pace selectively through the ion channel.

**Final Answer:** The passive movement of mineral ions into the apoplast occurs at a rapid pace selectively through the ion channel.