本题目来源于试卷: IB ESS Unit 2: Ecosystems & Ecology，类别为 IB环境系统与社会
[单选题]
Figure: Graph of the rate 79o / -rwvlc;shzpzee/:(w ez of photosynthesis at different temp ,;0)coibi r rzeratures
Suggest a possible conclusion from this graph.
A. There is more carbon dioxide produced at x than w.
B. The rate of photosynthesis increases with temperature.
C. The maximum amount of oxygen is produced at x.
D. The concentration of carbon dioxide is a limiting factor at y.
参考答案: C
本题详细解析:
Photosynthesis is a process where orgac:k)zgl0xys7i ooo1z2 zx;c ss 5 /cv7nic compounds are produced in cells using light energy, carbon dioxide and water. A product of photosynz zcoiy 0 c72:k5socgx7;lo/v1)zs xsthesis is oxygen gas. Hence, the rate of photosynthesis can be measured by the rate of carbon dioxide gas uptake or by the rate of oxygen gas production (Option A).
At x, this is known as the optimum temperature. The rate of photosynthesis is the highest here. In other words, x is the temperature where the maximum rate of carbon dioxide absorption and oxygen production occurs.
At y, light intensity and carbon dioxide concentration are not the limiting factors because, beyond the optimum temperature, the graph does not plateau but instead, it slopes downwards (Option D). At y, the rate of photosynthesis decreases because the temperature is affecting the enzymes involved in photosynthesis (Option B). Hence, the rate of photosynthesis does not just increase with temperature, it also decreases above the optimum temperature.
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