UNIT 3 TEST MATERIALS

3. 3. One of the researchers proposes using oxygen gas production to measure reaction rates. Which of the following statements best justifies the use of the proposed modification as a way of creating an appropriate control for the investigation?

• The experiment can be repeated without guaiacol, which will reveal the effect of guaiacol on the reaction rates

• The experiment can be repeated without hydrogen peroxide, which will help eliminate an uncontrolled

  variable.

• The experiment can be repeated without peroxidase, which will introduce a second independent

  variable.

• The experiment can be repeated without water, which will reveal whether the reaction can occur inside a

  living cell.

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NGSS.HS-PS1-5

1. 1. Based on Figure 1, which of the following statements best predicts the effect that a change from a moderately acidic environment ( near 6) to a basic environment will have on peroxidase activity?

• Peroxidase activity will increase.

• Peroxidase activity will increase at first and then decrease.

• Peroxidase activity will stay the same.

• Peroxidase activity will decrease.

5. 5. Acetylcholinesterase (AChE) is a protein that catalyzes the conversion of acetylcholine to acetate and choline.

   When the concentration of AChE in an aqueous solution is held constant, the rate of the reaction catalyzed by

   AChE increases with increasing concentrations of substrate. At low concentrations of acetylcholine, a small

   increase in the substrate concentration results in a large increase in the reaction rate. At high concentrations of

   acetylcholine, however, a large increase in the substrate concentration results in only a small increase in the reaction rate.

• The active site of AChE is specific for acetylcholine, and only one substrate molecule can occupy the active site at a time.

• AChE begins converting product into substrate as the acetylcholine concentration changes from low to

  high.

• AChE protein becomes denatured as the acetylcholine concentration changes from low to high.

• The substrate specificity of AChEchanges as the acetylcholine concentration changes from low to

  high.

7. 7. A set of five additional test tubes were prepared and used as controls. Which of the following best describes the

   contents expected to be contained in one of the five control test tubes?

• All five buffer solutions combined and hydrogen peroxide only

• pH 4 buffer solution and hydrogen peroxide only

• Water and yeast only

• Water, hydrogen peroxide, and yeast

Tags

NGSS.HS-PS1-5

NGSS.HS-PS1-2

2. 2. Which of the following actions will provide a negative control for the investigation?

• Repeating the experiment using twice the amount of hydrogen peroxide

• Repeating the experiment using heat-denatured peroxidase

• Repeating the experiment at 25C

• Repeating the experiment using twice the amount of peroxidase

11.Researchers investigated the effect of urea on the three-dimensional structure of a certain enzyme. The researchers

dissolved the enzyme in an aqueous buffer solution and added urea to the solution. The enzyme did not appear to

have a secondary or tertiary structure. The researchers carefully removed the urea from the solution and determined

that the enzyme had the original secondary and tertiary structure again.

Based on the results of the experiment, which of the following statements best predicts the effect of urea on the

enzyme’s function

• Function will be disrupted by adding the urea, but it will not be regained by removing the urea.

• Function will be gained by adding the urea and disrupted by removing the urea.

• Function will be unaffected by the addition and removal of the urea

• Function will be disrupted by adding the urea and regained by removing the urea.

8.A student designs an experiment to investigate the influence of temperature on enzyme function. The student’s plan is presented in Table 1. Which test tubes are controls in the experiment?

• Test tubes 1, 3, 5, and 7

• Test tubes 1 and 2 only

• Test tubes 5 and 6 only

• Test tubes 2, 4, 6, and 8

Tags

NGSS.HS-PS1-5

4. 4. Aminolevulinate dehydratase ( ALAD) is an enzyme that relies on zinc as a cofactor. A zinc ion binds to the

   ALAD active site, where it forms favorable interactions with the side chains of three amino acids. Researchers

   have found that substituting a lead ion for a zinc ion in the ALAD active site causes inhibition of ALAD.

   Which of the following statements best helps explain how the lead ion causes inhibition of ?

• It changes the amino acid sequence of the protein so that the enzyme catalyzes a different

  reaction.

• It changes the shape and charge of the substrate so that it becomes more compatible with ’s

  active site.

• It changes the three-dimensional structure of the active site so that is no longer compatible with

  its substrate.

• It changes the enzyme-substrate complex so that the transition state is more stable and the reaction proceeds at a faster rate.

9.Which of the following statements best helps justify the inclusion of group 2 as one of the controls in the experiment?

• It will show the average growth rate of seedlings that are maintained in a nonsterile environment.

• It will show whether the changes observed in group 1 depend on the metabolic activity of soil bacteria.

• It will show whether the changes observed in group 1 depend on the type of plants used in the

  experiment.

• It will show the changes that occur in the roots of seedlings following an infection by soil bacteria.

10.Which of the following statements best helps justify the inclusion of test tube 5 in the experiment?

• It will act as a control for test tube 4 by showing the effect of the presence or absence of the substrate.

• It will act as a control for test tube 4 by showing the effect of a change in environmental temperature.

• It will act as a control for test tube 6 by showing the effect of the presence or absence of the enzyme.

• It will act as a control for test tube 6 by showing the effect of a change in sodium chloride concentration.

Tags

NGSS.HS-PS1-5