Select an incorrect statement about mobilisation of minerals /food in plants

Options

A. buds need energy for growth and development of the photosynthetic apparatus
B. xylem movement can be upwards or downwards
C. the source-sink relationship is variable
D. direction of movement in the phloem can be upwards

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks us to select an incorrect statement about the mobilization of minerals and food in plants. We need to analyze each option provided to determine which statement is incorrect.

2. **Analyzing the Options**:
- **Option A**: "Birds need energy for growth and development of the photosynthetic apparatus."
- This statement is **correct** because birds, like all living organisms, require energy for growth, but it is not directly related to plants as they do not have a photosynthetic apparatus.

- **Option B**: "Xylem movement can be upwards or downwards."
- This statement is **incorrect**. Xylem movement is unidirectional, meaning it only moves upwards from the roots to the leaves. Therefore, this is the incorrect statement we are looking for.

- **Option C**: "The source-sink relationship is variable."
- This statement is **correct**. In plants, the source (where food is produced) and sink (where food is used or stored) can vary depending on the plant's needs and growth stages.

- **Option D**: "Direction of movement in the phloem can be upwards."
- This statement is **correct**. The phloem can transport nutrients both upwards and downwards, making it bidirectional.

3. **Conclusion**: After analyzing all the options, we find that the incorrect statement is **Option B**: "Xylem movement can be upwards or downwards." The correct understanding is that xylem movement is strictly upwards.

### Final Answer:
The incorrect statement about the mobilization of minerals/food in plants is: **"Xylem movement can be upwards or downwards."**

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