Unit 3 Progress Check MCQ

A researcher claims that a certain herbicide suppresses plant growth by inhibiting chloroplast function. To test the claim, the researcher treats isolated chloroplasts with increasing concentrations of the herbicide. The data from the experiment are presented in Table 1. Which of the following statements best clarifies how the data support the researcher's claim?

ATP synthase activity depends on a proton gradient across the thylakoid membrane.

A researcher claims that the initial rise of oxygen in Earth's early atmosphere, which occurred approximately 2.3 billion years ago, resulted from the metabolic activity of prokaryotic organisms. The claim is based on an interpretation of the geochemical and fossil evidence represented in Figure 1. Which of the following types of evidence will best support the researcher's claim?

Evidence that the cyanobacteria produced oxygen as a by-product of photosynthesis

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 and regained by removing the urea.

A researcher claims that spinach leaves capture the most energy from light waves in the range of 500 nmnm to 600 nmnm. To test the claim, the researcher will place spinach leaves in separate chambers and expose the leaves to different wavelengths of light. For each chamber, the researcher will measure the amount of oxygen gas (O2)(O2) that is produced in one hour. Which of the following graphs best represents data from the experiment that will support the researcher's cl

Graph B

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

It changes the three-dimensional structure of the active site so that ALAD is no longer compatible with its substrate.

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 6 by showing the effect of the presence or absence of the enzyme.

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

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

Which of the following statements correctly explains the observed effect of the acetylcholine concentration on the rate of the enzyme-catalyzed reaction?

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

Phycobiliproteins are a complex of accessory pigments and proteins found in cyanobacteria but not in green algae. A researcher claims that the phycobiliprotein pigments in cyanobacteria allow the cyanobacteria to survive in certain aquatic niches better than green algae can. Which of the following statements best justifies the researcher's claim?

The additional pigments absorb light at wavelengths that green algae cannot absorb; this may allow cyanobacteria to capture more light energy for photosynthesis than green algae can in certain areas.

Which of the following best predicts the immediate result of adding more substrate to the reaction mixture at the point indicated by the arrow in Figure 1?

The amount of product will increase until the reaction reaches its equilibrium point or until the substrate is used up by the reaction.

A researcher claims that the incorporation of carbon dioxide into organic molecules during photosynthesis does not violate the second law of thermodynamics. Which of the following statements best helps justify the researcher's claim?

The total system that includes photosynthetic organisms and the Sun becomes less ordered over time.

Which of the following statements provides reasoning that supports the claim that brown fatty tissue keeps an animal warm?

The uncoupling protein in this tissue reduces the proton gradient across the membrane and thus produces heat to warm the animal without ATP production.

A researcher claims that budding yeast are able to survive in different environments because they produce enzymes that allow them to use different molecules as sources of matter and energy. Which of the following statements best helps justify the researcher's claim by providing a relevant example?

Yeast cells produce invertase, which is an enzyme that catalyzes the conversion of the disaccharide sucrose into glucose and fructose.

Based on the data, scientists claim that the reproductive behavior of European flycatchers is influenced by the availability of energy sources. Which of the following statements best justifies this claim?

Young European flycatchers hatch from eggs when caterpillar biomass is available for the young birds to consume and convert into energy for growth.

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?

pH 4 buffer solution and hydrogen peroxide only

The active site of AChEAChE is specific for acetylcholine, and only one substrate molecule can occupy the active site at a tim

A molecule with negative charges interacts with positively charged side chains in the enzyme's active site.

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

Peroxidase activity will decrease.

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

Repeating the experiment using heat-denatured peroxidase

A researcher claims that genetic variation provides organisms with the ability to survive and reproduce in different environments. To support the claim, the researcher makes the following observation: bacteria that contain plasmids (small DNA molecules) are resistant to a wider range of antibiotics than are bacteria that contain no plasmids. Which of the following statements best establishes a connection between the observation and the researcher's claim?

Some plasmids contain antibiotic resistance genes.

Which test tubes are controls in the experiment?

Test tubes 1, 3, 5, and 7

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.