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Alcohol dehydrogenase (ADHADH) is an enzyme that aids in the decomposition of ethyl alcohol (C2H5OH)(C2H5OH) into nontoxic substances. Methyl alcohol acts as a competitive inhibitor of ethyl alcohol by competing for the same active site on ADHADH. When attached to ADHADH

Alcohol dehydrogenase (ADHADH) is an enzyme that aids in the decomposition of ethyl alcohol (C2H5OH)(C2H5OH) into nontoxic substances. Methyl alcohol acts as a competitive inhibitor of ethyl alcohol by competing for the same active site on ADHADH. When attached to ADHADH

methyl alcohol is converted to formaldehyde

The enzyme peroxidase is found in many organisms. It catalyzes the breakdown of hydrogen peroxide into water and oxygen gas. The rate of peroxidase activity at different pH values was assessed by students in the lab. The students' results are shown in graph 1.

If the experiment is repeated at pH 11

the observed activity level of the enzyme will most likely be

Protein digestion in humans is primarily carried out by three enzymes. Pepsin is found in the stomach (pH2)

where it aids in the breakdown of large proteins into smaller peptides

therefore

its enzymatic activity will decrease.

Amylase is a protein that catalyzes the conversion of starch to simple sugars. Amylase activity in an aqueous solution can be measured by using iodine as a starch indicator. A solution containing iodine and starch will have a dark-blue color

whereas a solution containing iodine but no starch will have a light-brown color. The color change of an iodine solution from dark blue to light brown can be used to measure the rate at which starch is converted to simple sugars. A student designs an experiment to investigate the effect of environmental pH on amylase function. The design of the experiment is presented in Table 1.

Which of the following statements best justifies the inclusion of test tube VV as a control in the experiment?

A researcher claims that some bacteria contain factors that influence the function of a particular enzyme but other bacteria do not. To test the claim experimentally

the researcher will grow two different bacterial strains in separate liquid cultures and isolate the contents of the cells in each culture. The researcher will add different combinations of cellular contents

A researcher designs an experiment to investigate the effect of environmental temperature on the function of an enzyme. For each trial included in the experiment

the researcher will add the enzyme and its substrate to an aqueous buffer solution and then measure the amount of product formed over 20 minutes. Which of the following must remain the same for all trials of this experiment?

Gelatin is a protein that is derived from collagen which is found in the bones

skin

A researcher claims that different enzymes exhibit maximal function over different pH ranges. To test the claim

the researcher carries out an experiment that includes three different enzymes: pepsin

A researcher claims that increasing the environmental temperature by 10°C will double the rate of an enzyme-catalyzed reaction. To test the claim

the researcher designs an experiment that uses a particular enzyme isolated from plants. The design of the experiment is presented in Table 1. For each test tube in the experiment

A researcher proposes a model of an enzyme-catalyzed reaction in which a reactant is converted to a product. The model is based on the idea that the reactant passes through a transition state within the enzyme-substrate complex before the reactant is converted to the product. Which of the following statements best helps explain how the enzyme speeds up the reaction?

The enzyme's active site binds to and stabilizes the transition state

Which of the following statements best helps explain the reaction specificity of an enzyme?

The shape and charge of the substrates are compatible with the active site of the enzyme.

The enzyme hexokinase catalyzes the conversion of glucose to glucose-6-phosphate

which is an important step in glycolysis. The reaction involves the transfer of a phosphate group from ATP to glucose. Either a glucose molecule or a water molecule can fit in the active site of hexokinase. The presence of a water molecule in hexokinase's active site would result in the hydrolysis of ATP to ADP instead of the conversion of glucose to glucose-6-phosphate. Which of the following statements best helps explain the reaction specificity of hexokinase?

Researchers investigated the influence of environmental pH on the activity of peroxidase

an enzyme that catalyzes the conversion of hydrogen peroxide to water and oxygen gas. In an experiment

Researchers investigated the influence of environmental pH on the activity of peroxidase

an enzyme that catalyzes the conversion of hydrogen peroxide to water and oxygen gas. In an experiment

Researchers investigated the influence of environmental pH on the activity of peroxidase

an enzyme that catalyzes the conversion of hydrogen peroxide to water and oxygen gas. In an experiment

Aminolevulinate dehydratase (ALAD) is an enzyme that relies on zinc as a coenzyme. 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 ALAD?

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 researcher proposes a model to explain how enzyme-substrate interactions determine enzyme specificity. The model is based on the idea that substrate molecules form favorable interactions with the amino acid side chains in an enzyme's active site. Based on the model

which of the following statements best explains an enzyme's specificity for a particular substrate molecule?

Catalase is an enzyme found in yeast cells that facilitates the chemical breakdown of hydrogen peroxide to water and oxygen gas. An experiment was conducted to determine the effect of pH on catalase function. Five buffer solutions of varying pH (2

4

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 Tube Substrate Added Enzyme Added Temperature (°C) 1 Yes No 10 2 Yes Yes 10 3 Yes No 20 4 Yes Yes 20 5 Yes No 30 6 Yes Yes 30 7 Yes No 40 8 Yes Yes 40

Test tubes 1

A researcher designs an experiment to investigate whether soil bacteria trigger the synthesis of defense enzymes in plant roots. The design of the experiment is presented in Table 1. For each group in the experiment

the researcher will determine the average rate of change in the amount of defense enzymes in the roots of the seedlings. Group Number of Seedlings Type of Soil Treatment Solution 1 10 Sterile potting soil Contains actively reproducing soil bacteria 2 10 Sterile potting soil Contains heat-killed soil bacteria 3 10 Sterile potting soil Contains no soil bacteria Which of the following statements best helps justify the inclusion of group 2 as one of the controls in the experiment?

Pectinase is a protein that catalyzes the breakdown of pectic polysaccharides in plant cell walls. A researcher designs an experiment to investigate the effect of salinity on the ability of pectinase to lower the activation energy of the reaction involved. The design of the experiment is presented in Table 1. For each test tube

the researcher will measure the amount of product formed over 20 minutes. Test Tube Sodium Chloride Concentration (molar) Temperature (degrees C) Substrate Added Pectinase Added 1 0 23 Yes No 2 0 23 Yes Yes 3 0.5 23 Yes No 4 0.5 23 Yes Yes 5 1.0 23 Yes No 6 1.0 23 Yes Yes 7 1.5 23 Yes No 8 1.5 23 Yes Yes Which of the following statements best helps justify the inclusion of test tube 5 in the experiment?

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?

In an experiment

a researcher prepares a reaction mixture by dissolving a substance in a buffered solution. The substance is the substrate of a certain enzyme. The researcher adds a small amount of the enzyme to the reaction mixture and measures the amount of product that is formed over time. The data are represented in Figure 1. 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?

European flycatchers feed caterpillars to their hatchlings. Graph 1 shows the average dates of hatching and fledging (leaving the nest)

and the biomass of the caterpillars between early May (when flycatcher young hatch) and June (when fledging of young occurs). Based on the data

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.

Brown fat is a type of fat tissue found in hibernating mammals. Inside the mitochondria of these fat tissue cells

these mammals have an uncoupling protein embedded in the inner mitochondrial membrane. This uncoupling protein allows hydrogen ions to leak from the intermembrane space back into the mitochondrial matrix. Figure 1 shows details of the processes in the inner mitochondrial membrane. Which of the following statements provides reasoning that supports the claim that brown fatty tissue keeps an animal warm?

A researcher claims that spinach leaves capture the most energy from light waves in the range of 500 nm to 600 nm. 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

A researcher claims that the initial rise of oxygen in Earth's early atmosphere

which occurred approximately 2.3 billion years ago

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. Herbicide Concentration (μg/L) pH Difference across Thylakoid Membrane ATP Production 0 3.5 Very high 2 2.5 Moderate 8 0.5 Very low 32 0 Very low Which of the following statements best clarifies how the data support the researcher's claim?

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?

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.

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