Long-distance transport of water , minerals , and food is generally carried out by

Options

A. diffusion only
B. active transport only
C. mass flow system
D. cytoplasmic streaming supplemented by active transport

Answer

To solve the question regarding the long-distance transport of water, minerals, and food in plants, let's break it down step by step:

### Step-by-Step Solution:

1. **Understanding the Components**:
- The question asks about the long-distance transport of water, minerals, and food in plants.
- The primary tissues involved in transport are xylem (for water and minerals) and phloem (for food).

2. **Identifying Transport Mechanisms**:
- **Diffusion**: This is a passive process that occurs over short distances and is not suitable for long-distance transport.
- **Active Transport**: This process requires energy and is also typically used for moving substances against their concentration gradient, but it is not the primary mechanism for long-distance transport of food.
- **Cytoplasmic Streaming**: This is the movement of cytoplasm within cells, which aids in the distribution of nutrients but is not the main long-distance transport mechanism.
- **Mass Flow System**: This refers to the pressure flow hypothesis, which explains how food (sugars) is transported in the phloem from sources (like leaves) to sinks (like roots or fruits).

3. **Applying the Pressure Flow Hypothesis**:
- The pressure flow hypothesis explains that sugars produced in the leaves (source) are transported through the phloem to other parts of the plant (sink) where they are needed.
- This process involves the movement of water and solutes, creating a pressure gradient that facilitates the mass flow of nutrients.

4. **Conclusion**:
- Based on the analysis, the correct answer to the question is that long-distance transport of water, minerals, and food is generally carried out by the **mass flow system**.

### Final Answer:
The correct option is **mass flow system**.