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Science · Drill 61

Science practice 61

13 questions ~9 min recommended
⏱ 00:00
Score
—

what I will

Oxygen Consumed (mm³)

Effect of Glucose on Respiration

40

30

10

10

Time (min.)

30

Control

Glucose + HCN

- Glucose + H₂S

HEN

Oxygen Consumed (mm³)

100-

80-

60-

Effect of Light on Respiration

Light

Dark

Light

Dark

20

Time (min.)

- CO

- N

Alumina-bead catalyst tube

1 mL syringe

60 mL syringe

Trial1234
Volume of Propanol (mL)10.50.75
Volume of Alumina Beads (g)1.7511.751.75
Volume of Propene (mL)58492845

B GI

reactant syringe

Palladium catalyst tube

receiver syringe

Trial1234
Volume of Hydrogen (mL)30303030
Volume of Propene (mL)30303030
Time Reactant Passed Over Catalyst(s)60453015
Volume of Propane in Receiver Syringe (mL)565249

Three substances have been shown to inhibit respiration in various organisms: hydrocyanic acid, hydrogen sulfide, and carbon monoxide. An experiment was conducted to determine the effect that each of these substances has on the respiration of the green alga Chlorella. Figure 1 shows the results.

image

Figure 1

Researcher 1 argued that glucose would have a contradictory effect on the alga, so that if the Chlorella were suspended in a solution containing 1 percent glucose, there would be less of an effect on respiration. Figure 2 displays the results of the experiment.

image

Figure 2

Researcher 2 hypothesized that light may play an active part in respiration of Chlorella, so an experiment was done to measure the effect of successive periods of light and darkness on the respiration of cells suspended in carbon monoxide and in nitrogen. The results are shown in Figure 3.

image

Figure 3

1. The theories of the two researchers are similar in that both researchers believe that:

2. According to Figure 1, Chlorella would typically consume about how much oxygen after half an hour?

3. If Researcher 1 was correct about the effect of glucose on the respiration of Chlorella, then based on the information in Figure 2, Researcher 1 would most likely predict that Chlorella suspended in a solution containing 2 percent glucose and HCN would consume how much oxygen after 20 minutes?

4. Does the data in Figure 3 support Researcher 2’s hypothesis?

5. Suppose a third researcher studied the effect of glucose and CO on the respiration of Chlorella, using the same conditions and methods as Researcher 1. After 20 minutes the results showed that the sample suspended in CO had consumed 50 mm3 of oxygen, while the sample suspended in a mixture of CO and glucose had consumed 60 mm3 of oxygen. How would this experiment most likely affect the researchers’ viewpoints?

6. According to Figure 2, which substance had the LEAST effect on respiration of Chlorella after 30 minutes?

7. According to Researcher 2, experiment findings indicate the following is FALSE regarding the relationship between Chlorella cells suspended in carbon monoxide and Chlorella cells suspended in nitrogen EXCEPT:

A catalyst is a substance that speeds up a reaction, but is chemically unchanged at the end of the reaction. Catalysts can be divided into two main types—heterogeneous and homogeneous. In a heterogeneous reaction, the catalyst is in a different phase (such as solid, liquid, or gas) from the reactants. In a homogeneous reaction, the catalyst is in the same phase as the reactants. Most examples of heterogeneous catalysis go through the same stages (see Table 1).

Table 1

Stage

Description

1

One or more of the reactants are absorbed onto the surface of the catalyst.

2

There is some sort of interaction between the surface of the catalyst and the reactant molecules, which makes them more reactive.

3

The reaction happens.

4

The product molecules are desorbed, meaning that the product molecules break away.

Students did experiments to convert propanol to propene using alumina beads, and then to convert propene to propanol using a palladium catalyst.

Experiment 1

Two glass syringes were connected to an aluminabead catalyst tube (see Figure 1). The 1 mL syringe was filled with 1 mL of propanol. Next, the apparatus was held above a burner’s flame and the alumina-bead catalyst tube was gently heated while the liquid propanol was slowly introduced into the catalyst tube. The liquid flowed through the tube until it hit the hot region. Then it vaporized, reacted with the catalyst, and exited the catalyst tube as gaseous propene into the 60-mL receiver syringe. The procedure was repeated with various amounts of propanol and alumina beads and the amount of gaseous propene collected was recorded (see Table 2).

image

Figure 1

Table 2

image

Experiment 2

A reactant syringe was filled with equal volumes of hydrogen and propene. The reactant syringe and receiver syringe were connected to the catalyst tube filled with solid palladium as shown in Figure 2. Then the hydrogenpropene mixture was slowly passed over the catalyst, the reaction occurred, and the propane was collected in the receiver syringe. The procedure was repeated several times, varying the amount of time the reactant was passed over the catalyst. The results are shown in Table 3.

image

Figure 2

Table 3

image

8. In Experiment 2, as the amount of time the reactant was passed over the catalyst decreased, the volume of propane created:

9. Which is the most likely explanation for why 0 mL of propane was produced in Trial 4 of Experiment 2?

10. What type of catalyst was used in Experiment 1?

11. In Experiment 2, the hydrogen-propene mixture turns into propane at what stage of the catalysis?

12. Based on the data in Table 2, which two trials illustrate the effect that varying the volume of the catalyst has on the volume of propene produced?

13. Which of the following best describes what occurred to the plunger of the 60-mL syringe during Experiment 1? When propanol was injected into the catalyst tube, the distance between the end of the plunger and the syringe tip:

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