2017年5月IB生物SL真题下载-Paper3
1. Urease is an enzyme that breaks down urea into ammonia and carbon dioxide. The ammonia produced causes the pH of the solution to rise. This reaction can be followed using a pH indicator or a pH probe.
In an experiment conducted by a student the time taken for the pH indicator, thymol blue, to change from yellow to blue was recorded at different temperatures.
(a) Outline what the standard deviations reveal about the data from this experiment.
(b) One result in this experiment can be classified as an outlier as its value is very distant from those of the other values.Explain an appropriate procedure for dealing with outliers.
(c) Outline the effect of temperature on the activity of urease enzyme.
(d) State one factor that would need to be controlled in this experiment.
2. Students exposed the water plant Cabomba caroliniana to different light intensities.The bubbles of oxygen gas released by the plant were counted each minute.
(a) Compare and contrast the experimental results for the effect of light intensity on the rate of photosynthesis of a green plant with the expected trend line.
C. caroliniana can grow well in water at 27°C. This experiment was carried out at 25°C.
(b) Describe the effect of carrying out the same experiment at 15°C.
(c) This experiment measured the quantity of oxygen gas released by the water plant. State one other way of measuring the rate of photosynthesis.
3. A spirometer was used to measure the ventilation rate of a person at rest and pedaling at 22 km per hour on an exercise bike.
(a) Calculate the difference in ventilation rate between resting and exercising.
(b) Explain the change in the tidal volume during exercise.
2017年5月IB生物SL真题余下省略！
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