本题目来源于试卷: Interaction & Interdependence C.2 Cell Respiration，类别为 IB生物学
[单选题]
A respirometer is a device that can be used to measure the r x+i:q5g*zgzr q8zy 3d espira lafldy +r,4dwm e,i31tion rate of germinating see 3lamywlei4,+ rdfd , 1ds.
In the experimental set-up shown above, how is the rate of oxygen uptake measured?
A. The volume of soda-lime is measured.
B. The displacement of gas in the syringe is measured.
C. A reading is taken from an oxygen sensor.
D. The temperature of the system is measured.
参考答案: B
本题详细解析:
A respirometer is a device th0vnb b zc8j5/sat is used to measure the rate of respiration. A basic feature of a respirometer is a sealed container containing the living organism and an alkaline substance such as soda-lime (Choice A) or potassium hydroxide to absorb the carbon dioxide gas, which is the product of respiration.
The rate of respiration is measured by a reduction in the volume of oxygen due to the oxygen consumed by the living organism. The reduction in the volume of oxygen inside the sealed container causes a reduction in pressure inside the container. This causes the syringe to move which is how oxygen consumption is measured (Choice B). The rate of respiration can then be calculated based on the amount of oxygen consumec8v/b5nzj b 0sd over a period of time.
An oxygen gas sensor (Choice C) can also be used to measure the reduction in the amount of oxygen. However, the experimental setup for this question does not include a sealed bio chamber bottle that is designed to fit the gas sensor probe. Since this experimental setup used a bung to seal the container, removing it to place an oxygen gas sensor probe inside the flask will not provide an accurate measurement of the amount of oxygen consumed.
When using a respirometer, the temperature is a controlled variable and should be kept constant (Choice D) to avoid changes to the volume of oxygen gas. Temperature also affects the rate of respiration. There should not be more than one independent variable being tested in an experimental setup.
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