Question

A research team is studying the effects of three different fertilizers (X, Y, and Z) on the growth of a specific plant species. They have four experimental plots with different fertilizer combinations: Plot 1: Fertilizer X only 
Plot 2: Fertilizer Y only 
Plot 3: Fertilizer X and Fertilizer Z only 
Plot 4: Fertilizer Y and Fertilizer Z only 

After a period of observation, they note the following: \[\begin{array}{rl} \bullet & \text{Plants in plots with Fertilizer X showed significantly increased height compared to a control group (no fertilizer).} \\ \bullet & \text{Plants in plots with Fertilizer Y showed a slightly increased leaf area compared to the control group.} \\ \bullet & \text{Plants in Plot 3 (X and Z) showed no significant difference in height compared to the control group.} \\ \bullet & \text{Plants in Plot 4 (Y and Z) showed significantly increased height compared to the control group.} \\ \end{array}\] Based on these observations, which of the following conclusions is best supported?

• A. Fertilizer Z inhibits the height growth promoted by Fertilizer X.
• B. Fertilizer Z enhances the leaf area increase caused by Fertilizer Y.
• C. Fertilizer X is the only fertilizer that significantly increases the height of this plant species.
• D. Fertilizer Z has no effect on the growth of this plant species.

Hint:

When interpreting experimental data, compare the effects of different combinations to determine interactions, such as inhibition or enhancement.

Answer 1

The Correct Option is A

Step 1: Review the observations: 

- Fertilizer X significantly increases height in Plot 1. 

- Fertilizer Y only slightly increases leaf area, not height. 

- Plot 3 (X and Z) shows no significant height difference, which suggests that Fertilizer Z may inhibit the effect of Fertilizer X. 

- Plot 4 (Y and Z) shows significantly increased height, indicating that Fertilizer Z is effective when combined with Fertilizer Y. 

Step 2: Analyze the conclusions: 

- Conclusion (a) is supported by the observation that Fertilizer Z seems to reduce the height increase from Fertilizer X, as seen in Plot 3. 

- Conclusion (b) is not directly supported, as the increase in leaf area for Fertilizer Y was minimal. 

- Conclusion (c) is incorrect because Fertilizer Z in combination with Fertilizer Y also showed increased height in Plot 4. 

- Conclusion (d) is incorrect because Fertilizer Z did affect the plant growth when combined with Fertilizer Y. 

Thus, the best-supported conclusion is (a).