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Increased carbon dioxide levels are known to increase plant growth. For example, a recent study of wheat has shown that increased carbon dioxide results in a greater crop yield per acre of land. The study controlled for differences in watering, the use of fertilisers, and soil type and quality. The study also found that the increased yield resulting from increased carbon dioxide had a strong negative correlation with the amount of protein and nutritional value of each kilogram of wheat. The researchers hypothesised that the reason for this was because the growth was not accompanied by a similar increase in nutrient intake. In essence, they argued that the yield increased and diluted the protein and nutritional content for each kilogram.
Consider the following incomplete sentence: As wheat yields increase because of increased carbon dioxide, the 1 decreases because the 2 has not increased. Select for 1 and for 2 the options that create the sentence that most accurately states the main point of the passage above. Make only two selections, one in each column.
the entire yield
nutritional and protein content for each kilogram
amount of nutrients that the plants take in
amount of carbon dioxide that the plants receive
dilution of protein and nutritional content
| Passage Statement | Analysis & Implications |
| "Increased carbon dioxide levels are known to increase plant growth" |
|
| "Study of wheat has shown that increased carbon dioxide results in a greater crop yield per acre" |
|
| "The study controlled for differences in watering, the use of fertilisers, and soil type and quality" |
|
| "Increased yield...had a strong negative correlation with the amount of protein and nutritional value of each kilogram of wheat" |
|
| "Researchers hypothesised...growth was not accompanied by a similar increase in nutrient intake" |
|
| "Yield increased and diluted the protein and nutritional content for each kilogram" |
|
We need to complete: "As wheat yields increase because of increased carbon dioxide, the [1] decreases because the [2] has not increased."
For Part 1: The passage explicitly states that protein and nutritional value per kilogram decreases
For Part 2: The researchers hypothesize that nutrient intake/uptake hasn't increased proportionally
Let's evaluate each option:
Part 1: "nutritional and protein content for each kilogram" - This is what decreases
Part 2: "amount of nutrients that the plants take in" - This is what hasn't increased proportionally
Completed sentence: "As wheat yields increase because of increased carbon dioxide, the nutritional and protein content for each kilogram decreases because the amount of nutrients that the plants take in has not increased."
This perfectly captures the passage's main point about the dilution effect caused by disproportionate growth versus nutrient uptake.