本题目来源于试卷: Continuity and Change D.11 Stability & Change，类别为 IB生物学
[单选题]
A student set up an aquatic mesocosm7a8 jtk/prmm2*5nrcfeok v3aap9 .j1 using a commercially available seawater-fqz*) 1i a:le/yho.qtzi9h m v)illed glass orb, which included algae, shrimp, some corals and gravel. The student placed it near a window to provide a light source. Which of the following sta9oqq*almi ) e hv/z.t1yi:) zhtements are true?
I. The algae are autotrophs, produce carbon compounds and provide oxygen for organisms in the mesocosm
II. Saprotrophs present in the water and gravel help to recycle nutrients found in dead organisms
III. Herbivores usually present in a natural ecosystem can be excluded in the mesocosm
A. I only
B. I and II only
C. II and III only
D. I, II and III
参考答案: D
本题详细解析:
All the statements are true. A mesocosm is a stable, small representation of an ecosystem and can be used to study how one factor in an ecosystem affects other factors in an ecosystem. In all ecosystems, energy is lost and autotrophs such as algae or green plants generate the energy needed for the ecosystem. Saprotrophs are necessary for nutrient cycling, which is why no external addition of nutrients is generally required. Herbivores are not necessary for mesocosms to be stable as autotroph abundance is also regulated by the availability of resources such as nutrients and light. The only choice that includes all three statements is Choice C. All other choices (A, B and C) are therefore incorrect.
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