Question 155·Medium·Command of Evidence
Growth Indicators for Basil Plants after 6 Weeks
| Indicator | Mean value for plants under red–blue LED lighting | Mean value for plants under sunlight (control) |
|---|---|---|
| Height increase (cm) | 12.5 | 8.3 |
| Leaf count | 18 | 12 |
| Chlorophyll content (relative units) | 45 | 37 |
To explore whether specialized lighting boosts plant growth, greenhouse researchers compared basil plants grown under full-spectrum sunlight (the control group) with plants grown under red–blue LED lights. Higher numbers on each indicator reflect more vigorous growth or health.
Compared to the mean values for plants grown under sunlight, the mean values for plants grown under red–blue LED lighting ______
Which choice most effectively uses data from the table to complete the statement?
For table-based Reading & Writing questions, first restate in your head what you are being asked to compare (here, LED vs. sunlight means). Then, row by row, quickly compare each pair of numbers and note whether the experimental group is higher or lower. Once you see the pattern, eliminate any choices that contradict the basic comparisons (wrong direction, wrong count of indicators) or that refer to information the table does not provide (such as variation among individual plants). Finally, pick the remaining choice that best summarizes both the numerical pattern and the overall conclusion (better or worse performance).
Hints
Focus on mean values, not individual plants
The table gives mean (average) values for each group, not scores for individual plants. Look for an option that talks about how the averages compare between the two groups.
Compare each pair of numbers in the table
For each indicator (height, leaf count, chlorophyll), compare the red–blue LED value to the sunlight value. Decide whether each LED value is higher, lower, or the same.
Watch out for answer choices mentioning ranges or variation
Ask yourself: Does the table show how spread out the data are for individual plants, or does it only show single mean values for each group? Eliminate any answer that talks about variation that the table does not provide.
Check whether the overall conclusion is positive or negative
Once you know whether the LED numbers are higher or lower, pick the answer whose overall conclusion (better or worse growth) matches what the numbers show.
Step-by-step Explanation
Identify what the question is asking
The question asks you to compare the mean values for basil plants under red–blue LED lighting to the mean values for plants under sunlight and choose the statement that correctly summarizes that comparison.
Compare the first indicator: height increase
Look at the Height increase (cm) row:
- Red–blue LED: 12.5
- Sunlight: 8.3
Since , plants under red–blue LEDs had a greater mean height increase.
Compare the second and third indicators
Now check the other rows:
- Leaf count: Red–blue LED is 18; sunlight is 12. Since , the LED plants had more leaves on average.
- Chlorophyll content: Red–blue LED is 45; sunlight is 37. Since , the LED plants had higher chlorophyll content on average.
So for all three indicators, the red–blue LED group has higher mean values than the control group.
Match your findings to the best summary statement
You need an answer choice that says the red–blue LED mean values are higher on all three indicators and that this suggests better overall growth or health. The only choice that correctly matches the data and gives that overall interpretation is “were higher for all three indicators, indicating overall enhanced growth for these plants.”