Self-study
P1
Experts anticipate that global atmospheric concentrations of carbon dioxide (CO2) will have doubled by the end of the twenty-first century. ██ ██ █████ ████ ███ ███ ██████████ ██ ██████ ███████ ██ ████████ █████ ██████ ████ ██ █████ ██████████ ██ ████ ████ ███ ███████ ████████ ███
Intro topic ·
Global CO2 will probably increase
CO2 contributes to global warming.
Perspective from some research ·
Increased CO2 can lead to agricultural abundance, which can decrease rate of global warming
If there are more plants, those plants might draw more CO2 from the atmosphere, which might slow down global warming.
P2
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Critique 1 ·
More CO2 could lead to less agricultural yields
Although CO2 increases plant growth rate, it affects some plants more than others. Weeds might grow faster and outcompete certain good plants.
Consequence of Critique 1 ·
Different growth rates in plants can damage ecosystems
Weeds burn easily. More weeds could lead to more fires.
P3
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Critique 2 ·
More CO2 unlikely to slow down rate of global warming
Support for Critique 2 ·
Global warming leads to more decomposing peat, which will release more CO2 into atmosphere
Although more CO2 can lead to more plant growth, which can absorb more CO2, that's counteracted by increased release of CO2 from peat.
Passage Style
Critique or debate
21.
Which one of the following, ██ █████ ██ █████ ██████████ ████ ███ ██████████ █████████ ██
a
The roots of █ ███████ ████ ███████ ████ ████ ███████ ████ ███ ██████ ██ ███ ██ ███ ██████████ ██████████ ████ ██████████ ███ █████ ██ ██████ ████ ████████ ████████ █████████ ██ ███████ ████ ████ ██████████████ █████████████
This is consistent with the hypothesis because it shows plants with higher photosynthetic efficiencies losing their advantage in an atmosphere high in CO2.
b
When grown in ██ ██████████ ████ ██ ████ ███████ █████ ████ ███ ██████████████ ████████████ █████ ██ ██████ ██ ██████████ █████████ ████████ █████████ ██ ████████████ ██████
This is consistent with the hypothesis because it shows plants with lower photosynthetic efficiencies thriving in an atmosphere high in CO2, while agricultural crops lose their advantage.
c
When trees of █ ███████ ████ █ ████ ██████████████ ██████████ ███ ███████ ██ █ ███████ ████ █ ███ ██████████████ ██████████ ████ ██████ ██ ██ ██████████ ████ ██ ████ ███ █████ ████ ████ ███████ ████ ███ ████████
This is not consistent with the hypothesis because it shows plants with higher photosynthetic efficiencies growing more quickly than those with lower photosynthetic efficiencies in an atmosphere high in CO2. The hypothesis predicts the opposite.
d
When two different ███████ ██ █████ ████ ██████████ ██████████████ ██████████ ████ ██████ ██ ██ ██████████ ████ ██ ████ ███ ███████ ████ ████ ████ ███████ ███ ███████ ███ ██████████████ ███████ ███ ██ ███ ███████ █████
The hypothesis doesn’t apply here, since it compares plants with higher photosynthetic efficiencies to those with lower photosynthetic efficiencies, while (D) compares plants with the same photosynthetic efficiency.
e
The number of ██████████ ██████ █████████ ██ ██ ██████████ ████ ██ ████ ████ ███████████ ████ █████████ ███ ████████ ███ █████ ██ █████ ███████ ████ █████ ██████ ██ ███████ █████████
The hypothesis doesn’t apply here, since it compares plants with higher photosynthetic efficiencies to those with lower photosynthetic efficiencies, while (E) doesn’t mention photosynthetic efficiency at all.