Chapter 3 Test Ap Bio

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 V as a control in the experiment?

It will show the color change that occurs in the absence of enzyme activity.

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, substrate, and enzyme to test tubes containing a buffer solution adjusted to the optimal pH of the enzyme and then measure the rate of product formation. The design of the researcher's experiment is presented in Table 1.
Which of the following statements best justifies the inclusion of test tubes 3 and 7 in the experiment?

They will show whether the isolated cellular contents have enzymatic activity.

Gelatin is a protein that is derived from collagen which is found in the bones, skin, and connective tissue of animals. To investigate the ability of various enzymes to digest gelatin, a group of students set up an assay involving camera film. Camera film contains gelatin and appears black when exposed to light but turns clear as the gelatin gets broken down. The students incubated pieces of exposed camera film in test tubes, each containing one of three different enzyme solutions (trypsin, lipase, or amylase) as indicated in Figure 1. The students recorded the time it took for the enzymes to digest the gelatin in each test tube, turning the film from black to clear.
Which of the following would be the most appropriate control for this experiment?

A test tube containing a piece of exposed camera film submerged in water

For following group of questions first study the description of the data and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet.
To study the actions of the enzyme catalase on hydrogen peroxide, students performed the following experiment. Catalase was extracted from potatoes by blending raw potatoes in a blender with cold distilled water. The filtrate was stored on ice. The following hydrogen peroxide solutions were made: 1 percent, 5 percent, 10 percent, and 15 percent. Filter paper disks were soaked in the catalase filtrate and dropped into beakers containing the various solutions. The activity of the enzyme was measured by the amount of time it took for the disks to float to the surface of the solution on the bubbles produced by the reaction. The following data were obtained.
If the potato solution was boiled for 10 minutes and cooled for 10 minutes before being tested, the average time for the disks to float to the surface of the hydrogen peroxide solution would be

more than 30 seconds

Enzymes with their highest activity at an alkaline (basic) pH are represented by which of the following graphs?

II only

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?

Responses

Repeating the experiment using heat-denatured peroxidase

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.

Some organisms use a weaker terminal electron acceptor than oxygen during cellular respiration. Which of the following best explains why the cells of these organisms might generate less ATP per molecule of glucose than cells that use oxygen as the terminal electron acceptor?

The cells of these organisms create a smaller proton gradient than cells that use oxygen.

The electron transport chain (ETC) is made up of several carrier molecules that transport electrons. These carrier molecules are found within membranes.

Which of the following statements best explains why these carrier molecules are typically found within membranes?

The energy derived from the ETC creates a difference in the concentration of protons on either side of the membrane.

Which of the following best explains why the inner mitochondrial membrane has more embedded proteins of the electron transport chain than the outer mitochondrial membrane?

The Krebs cycle occurs in the mitochondrial matrix and not the intermembrane space.

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

Which test tubes are controls in the experiment?

Test tubes 1, 3, 5, and 7

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.

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 and regained by removing the urea.

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.

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 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 cla

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 production.

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

Which of the following graphs best represents data from the experiment that will support the researcher’s claim?

Which of the following types of evidence will best support the researcher’s claim?

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

Which of the following statements best clarifies how the data support the researcher’s claim?

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

A researcher claims that increasing the environmental temperature by 10°C10°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, the researcher will measure the rate of product formation.

Which of the following statements best helps justify the inclusion of test tube 5 as a control in the experiment?

It will provide a measurement of product formation in the presence of a denatured enzyme.

A researcher claims that different enzymes exhibit maximal function over different pHpH ranges. To test the claim, the researcher carries out an experiment that includes three different enzymes: pepsin, salivary amylase, and arginase. The results of the experiment are represented in Figure 1.

Which of the following actions will provide the most appropriate negative control for the experiment

Repeating the experiment with denatured enzymes

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?

The initial concentration of the substrate

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 decreases the activation energy of the reaction.

The enzyme hexokinase catalyzes the conversion of glucose to glucose-6-phosphate, which is an important step in glycolysis. This 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 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?

Glucose has the right shape and charge to cause hexokinase to undergo a structural change needed for Catalyst, whereas water does not.

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 V as a control in the experiment?

It will show the color change that occurs in the absence of enzyme activity.

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

lower than the level at pHpH 9

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, while trypsin and chymotrypsin are found in the small intestine (pH8), where they aid in the further breakdown of the proteins into amino acids and dipeptides that can be absorbed into the bloodstream. Graph 1 shows the effect of pH on the activity levels of the three enzymes.

Which of the following best predicts how the structure and function of pepsin will change as it enters the small intestine?

Pepsin will change in shape because of the basic environment of the small intestine; therefore, its enzymatic activity will decrease.

Pepsin will change in shape because of the basic environment of the small intestine; therefore, its enzymatic activity will decrease.

ATP hydrolysis is an energy-releasing reaction that is often coupled with reactions that require an input of energy.

A researcher claims that only a portion of the light energy captured by green plants is available for growth and repair.
Which of the following observations best helps justify the researcher's claim?

As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat.

As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat.

ATP production by the phosphagen system increases and decreases rapidly following the start of the exercise period.

A researcher claims that increased atmospheric carbon dioxide levels cause increased growth rates in plants.
Which of the following statements best supports the researcher's claim?

Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds.

In chloroplasts, ATP is synthesized from ADP plus inorganic phosphate (Pi) in a reaction catalyzed by ATP synthase molecules that are embedded in the thylakoid membrane.
Which of the following statements provides evidence to support the claim that no ATP will be synthesized in the absence of a proton gradient across the thylakoid membrane?

No ATP is synthesized when channel proteins that allow the free passage of protons are inserted into the thylakoid membrane.

A scientist claims that Elysia chlorotica, a species of sea slug, is capable of photosynthesis.
Which of the following observations provides the best evidence to support the claim?

Elysia chlorotica grows when exposed to light in the absence of other food sources.

A researcher claims that different metabolic pathways allow bacteria 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?

E. coli bacteria reproduce in liquid media containing either glucose or galactose.

Cyanobacteria contain a variety of pigment molecules, as shown in Table 1. As a result, the color of cyanobacteria cultures can vary significantly based on the relative amount of each pigment produced.
A researcher placed a culture of cyanobacteria under green lights. Within a few weeks, the appearance of the cyanobacteria changed from green to red. The researcher claimed the color change in the culture was the result of an adaptation allowing greater photosynthesis.
Which of the following provides the best reasoning to justify the researcher's claim?

In green light, more phycoerythrin molecules are produced, allowing more green light to be absorbed, thus increasing photosynthesis.

Graphs representing enzymes sensitive to changes in pH include which of the following?

I, II, and III only

A scientist determined the rate of an enzyme-catalyzed reaction by measuring the amount of product formed over time. The following curve was generated from the data collected.
During which time interval is the reaction rate lowest?

4-5 minutes

Which of the following best describes why the disks rose to the surface faster in the more concentrated hydrogen peroxide solutions?

The higher substrate concentrations in the more concentrated solutions speeded the reaction.

The following data were obtained.

Place a catalase-soaked disk in a beaker of water.

Which of the following best describes why ice was used during this experiment?

To retard the breakdown of the catalase

The following questions refer to an experiment that is set up to determine the relative volume of O2 consumed by germinating and nongerminating (dry) pea seeds at two different temperatures. The change in volume is detected by using a respirometer over a given period of time. The data are given below.
The rate of oxygen consumption in germinating pea seeds at 26ºC is

0.05 mL / min

The following data were obtained.

yellow-leaved seedlings were unable to convert light energy to chemical energy

Based on the data shown, changes in the light intensity resulted in changes in the rate of which of the following processes?

Photosynthesis

The rate of oxygen production equaled the rate of oxygen consumption during which of the following time periods?

J to K

Which of the following questions will best direct an investigation of the mechanism of ATP synthase?

Is the phosphorylation of ADP by ATP synthase dependent on the formation of a proton gradient?

The figure above shows an organelle typically found in eukaryotic cells. Which of the following best describes the function of the double membrane system of this organelle?

The inner membrane has specialized proteins that create a hydrogen ion concentration gradient between the intermembrane space and the matrix.

What most likely causes the trends in oxygen concentration shown in the graph above?

Photosynthesis produces more oxygen than is consumed by respiration during the day.

The fact that each line on the graph rises from left to right means that

larger fish consume more oxygen than smaller fish at all four temperatures

Which of the following best accounts for the shape of the solid line between points A and D?

ATP acted as an allosteric inhibitor on one or more of the enzymes.

It is most reasonable to hypothesize that, in the breakdown of glucose, substance X

an inhibitor

The chemical reaction for photosynthesis is
6 CO2 + 12 H2O + light energy → C6H12O6 + 6 O2 + 6 H2O
If the input water is labeled with a radioactive isotope of oxygen, 18O, then the oxygen gas released as the reaction proceeds is also labeled with 18O. Which of the following is the most likely explanation?

During the light reactions of photosynthesis, water is split, removing electrons and protons, and oxygen gas is released.

During aerobic cellular respiration, oxygen gas is consumed at the same rate as carbon dioxide gas is produced. In order to provide accurate volumetric measurements of oxygen gas consumption, the experimental setup should include which of the following?

A substance that removes carbon dioxide gas

According to the data, the mice at 10o C demonstrated greater oxygen consumption per gram of tissue than did the mice at 25o C. This is most likely explained by which of the following statements?

The mice at 10o C had a higher rate of ATP production than the mice at 25o C.

During aerobic cellular respiration, oxygen gas is consumed at the same rate as carbon dioxide gas is produced. In order to provide accurate volumetric measurements of oxygen gas consumption, the experimental setup should include which of the following?

A substance that removes carbon dioxide gas

Which of the following hypotheses is best supported by the results of this experiment?

Metabolic rate per gram of tissue is higher in smaller mammals.

Which of the following would most adversely affect the validity of this experiment?

Large variation in metabolic rates between individuals of a species

The rate of the reaction could also be determined by

measuring the change in the amount of substrate

PFK can be allosterically inhibited by ATP at high concentrations. Which of the following is the benefit of regulating glycolysis by the concentration of ATP?

Glycolysis proceeds when the intracellular concentration of ATP is low, which provides ATP to drive cellular reactions.

scientist determined the rate of an enzyme-catalyzed reaction by measuring the amount of product formed over time. The following curve was generated from the data collected.

What is the most likely explanation for the change in the slope of the line between 3 and 5 minutes?

A large amount of the substrate had been consumed.

The figures below illustrate the similarities between ATP synthesis in mitochondria and chloroplasts.

The figures can best assist in answering which of the following questions?

Do electron transport chains create a gradient so that ATP synthase can generate ATP molecules?

According to the results of this experiment, germination of tobacco seeds during the first week is

increased by exposure to light

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

Responses

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