Spectrophotometers are instruments that measure the absorbance of light of a certain wavelength by a liquid. Because color changes with wavelength of light, spectrophotometers can be used to note subtle changes in color. A standard spectrophotometer is shown in Figure 1.
Students were investigating the rate of cellular respiration (metabolism of sugar) in mitochondria of lima beans.
The students added DPIP, a blue chemical reagent, to each of their test tubes. As cellular respiration was carried out, this reagent changed from blue to colorless.
The students prepared three test tubes, as shown in Table 1. Each test tube was then inserted into the spectrophotometer and the absorbance was set to 600 nm, the wavelength best absorbed by DPIP. Every five minutes for twenty minutes, absorbances were measured for each tube.
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Based on the information in the passage and Table 1, which tube, if any, acted as the control?CorrectIncorrect
Before the students recorded the absorbance readings from the spectrophotometers, they predicted which tube would show faster color changes. Which of the following hypotheses was most likely confirmed by their results? Faster color change would occur in:CorrectIncorrect
One of the students accidentally turned the wavelength control and reset the machine to 430nm. Would this have affected the experimental results?CorrectIncorrect
The students wanted to next test the effect of different amounts of mitochondrial suspensions on cell respiration. Which of the following experimental designs would accomplish this?CorrectIncorrect
Based on the passage and Figure 1, the students should turn the wavelength adjustment knob to which of the following wavelengths?CorrectIncorrect