We would expect the greatest difference in plant health between two groups of plants of the same species, one group with mycorrhizae and one group without mycorrhizae, in an environment

Options

A. where nitrogen-fixing bacteria are abundant.
B. that has soil with poor drainage.
C. that has hot summers and cold winters.
D. in which the soil is relatively deficient in mineral nutrients.

Answer

To determine the environment in which we would expect the greatest difference in plant health between two groups of the same species—one with mycorrhizae and one without—we can follow these steps:

### Step-by-Step Solution:

1. **Understand Mycorrhizae**: Mycorrhizae are symbiotic associations between plant roots and fungi. They play a crucial role in enhancing nutrient uptake, particularly phosphorus and other essential minerals.

2. **Function of Mycorrhizae**: The fungi associated with mycorrhizae extend their hyphae into the soil, which increases the surface area for absorption. This allows plants to access more nutrients than they would be able to on their own.

3. **Nutrient Absorption**: With the increased surface area provided by the fungal hyphae, plants can absorb more nutrients, especially in soils that are deficient in minerals. This leads to healthier plant growth.

4. **Identify the Environment**: To find the environment where the difference in plant health would be most pronounced, we need to consider conditions where nutrient availability is limited.

5. **Evaluate Options**:
- **Option A**: Soil with abundant nitrogen-fixing bacteria - This is not directly related to mycorrhizae and would not show a significant difference.
- **Option B**: Soil with poor drainage - While drainage can affect plant health, it does not directly correlate with the presence of mycorrhizae.
- **Option C**: Soil that is relatively deficient in mineral nutrients - This is the most relevant option as mycorrhizae would significantly enhance nutrient uptake in such conditions, leading to a greater difference in plant health.

6. **Conclusion**: The environment where we would expect the greatest difference in plant health between the two groups of plants is one that is relatively deficient in mineral nutrients. This is because mycorrhizae would provide a substantial advantage in nutrient uptake, leading to healthier plants.

### Final Answer:
The greatest difference in plant health would be expected in an environment that is relatively deficient in mineral nutrients.

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