2018年5月IB生物SL真题下载-Paper3
1. A study was carried out on the activity of catalase in bacteria living in extreme environments. Catalase decomposes hydrogen peroxide (H2O2). The data were obtained for a strain of bacteria called Vibrio rumoiensis which exhibits high catalase activity.
(a) Describe the relationship between increasing H2O2 concentration and catalase activity.
(b) Identify two factors that would need to be controlled in generating these data.
(c) Evaluate the claim that, based on the data, the optimum H2O2 concentration for catalase is 70 mM.
2. The mesocosms shown were placed in a freshwater lake to investigate the impact of water mixing on the biomass of zooplankton (microscopic consumers). Each mesocosm is filled with lake water, sealed at the bottom and sides, and open to the air at the top. The water in each mesocosm was mixed either by moving a flat disc up and down or by bubbling air through the water. In the control there was no active mixing.
(a) Based only on the data in the graph, outline the effect of different mixing methods on the biomass of zooplankton.
(b) Outline the advantages of using mesocosms to study ecological relationships.
(c) State one possible error that could affect a mesocosm experiment of this type.
3. The image is a transmission electron micrograph of part of two adjacent pancreatic cells.
(a) Using the scale bar, determine the diameter of the nucleus of the cell on the left, giving the units.
(b) Deduce the magnification of the image.
(c) Identify the structure labelled A.
2018年5月IB生物SL真题余下省略！
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