A strain of bacteria that has the gene which endows it with the property of multiduring resistance assuming that this strain is selected by nature which one of the following would represent its trend of growth?

Options

A. Stabilising selection
B. Disruptive selection
C. Directrional selection
D. Diversifying selection

Answer

To solve the question regarding the trend of growth of a strain of bacteria that possesses a gene for multi-drug resistance, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Multi-Drug Resistance**:
- The strain of bacteria has a gene that allows it to resist multiple drugs. This means that the bacteria can survive in environments where various antibiotics are present.

2. **Natural Selection Context**:
- In nature, organisms that have advantageous traits (like multi-drug resistance) are more likely to survive and reproduce. This leads to an increase in the frequency of that trait in the population over time.

3. **Identifying the Type of Selection**:
- We need to determine which type of natural selection applies to this scenario. The options provided include stabilizing selection, disruptive selection, directional selection, and diversifying selection.

4. **Evaluating Stabilizing Selection**:
- Stabilizing selection favors intermediate phenotypes over extreme ones. In the context of multi-drug resistance, the intermediate forms (bacteria that can resist multiple drugs) are more likely to survive than those that are resistant to only one drug or none at all.

5. **Evaluating Other Types of Selection**:
- **Disruptive Selection**: This type favors extreme phenotypes and would not apply here since we are focused on multi-drug resistance, which is an intermediate trait.
- **Directional Selection**: This type favors one extreme phenotype over others, which does not fit the scenario of multi-drug resistance.
- **Diversifying Selection**: This type favors multiple extreme phenotypes, which again does not apply to the intermediate nature of multi-drug resistance.

6. **Conclusion**:
- Since the intermediate forms (multi-drug resistant bacteria) are favored in this scenario, the correct type of natural selection that represents the trend of growth of this bacterial strain is **stabilizing selection**.

### Final Answer:
The trend of growth of the strain of bacteria that has the gene for multi-drug resistance, assuming it is selected by nature, would represent **stabilizing selection**.

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