2018年11月IB生物SL真题下载-Paper3
1. A variegated Pelargonium plant was grown outdoors in a plant pot. Figure 1 shows one leaf of the Pelargonium. The plant was left in the dark for 24 hours to inhibit photosynthesis. After this time, a sketch was made of the leaf to show the colours (Figure 2), then part of the leaf was covered with black card (Figure 3). Following the exposure of the plant to sunlight for six hours, the black card was removed and the leaf tested for starch (Figure 4).
(a) Outline a reason for inhibiting photosynthesis for 24 hours.
(b) (i) Identify which two areas, W, X, Y or Z, in Figure 4 show that light is required for photosynthesis.
(ii) Identify which two areas, W, X, Y or Z, in Figure 4 show that chlorophyll is required for photosynthesis.
(iii) Discuss briefly whether the detection of starch in this experiment was proof that photosynthesis had occurred in the leaf.
(c) (i) Using the axes, sketch the action spectrum for photosynthesis in the green area of the leaf in Figure 1.
(ii) Predict how the action spectrum from the white areas of the leaf would differ from the green areas.
(d) Suggest reasons that plants with variegated leaves are rarely found growing wild naturally.
2. Measurements of the lung capacity of a student were recorded using a spirometer and displayed with a data logger. Initially the student was at rest, then changed to carrying out strenuous exercise. The results are displayed in the graph.
(a) Calculate the ventilation rate at rest, giving the units.
(b) Explain the changes in ventilation after 35 seconds.
(c) Suggest how the total lung volume at rest would differ for a patient with emphysema.
3. The micrograph shows mitosis in a cell of an onion (Allium cepa) root tip.
(a) Deduce, with a reason, which stage of mitosis is shown.
(b) The cells visible in the onion root tip were classified and counted.
2018年11月IB生物SL真题余下省略！
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