AP Bio Unit 3 MCQ

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.

In addition to the pigments commonly associated with photosynthesis, a certain photosynthetic species contains two additional pigment types. Which of the following best supports the claim that this species is better adapted to environmental changes than other photosynthetic species are?

The additional pigments allow the species containing them to harvest energy from wavelengths of light that the other photosynthetic species cannot use. multiple pigments = reflect more light

induced fit model of enzyme activity suggests

The binding of substrate changes the conformation of the active site to bind substrate more tightly

In most freshwater fish, nitrogenous waste is primarily excreted as ammonia, which is highly soluble in water and is toxic at low concentrations. In terrestrial mammals, ammonia is converted to urea before it is excreted. Urea is also highly soluble in water but is less toxic than ammonia at low concentrations. Which of the following best explains why freshwater fish do not convert ammonia to urea for excretion? A. The metabolic pathways of fish do not normally involve nitrogen consumption. B. The dilution of ammonia by direct excretion into freshwater conserves energy. C. Ammonia is concentrated in tissues, where it is stored prior to excretion. D. The nitrogen in ammonia is recycled for use in protein and nucleotide synthesis.

The dilution of ammonia by direct excretion into freshwater conserves energy.

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. Speeds up reaction because it requires less activation energy so less time.

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, the researchers added a hydrogen peroxide solution containing guaiacol to several identical test tubes and adjusted the solution in each test tube to a different pH. The researchers included the guaiacol because it caused the solutions to change color as the reactions proceeded, which the researchers relied on for measuring reaction rates. Finally, the researchers added the same amount of peroxidase to each test tube and measured the rate of each reaction at 23°C. The results of the experiment are represented in Figure 1.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.

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

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

Which of the following is an important difference between light-dependent and light-independent reactions of photosynthesis? A. The light-dependent reactions occur only during the day; the light-independent reactions occur only during the night. B. The light-dependent reactions occur in the cytoplasm; the light-independent reactions occur in chloroplasts. C. The light-dependent reactions utilize CO2 and H2O; the light-independent reactions produce CO2 and H2O. D. The light-dependent reactions depend on the presence of both photosystems I and II; the light-independent reactions require only photosystem I. E. The light-dependent reactions produce ATP and NADPH; the light-independent reactions use energy stored in ATP and NADPH.

The light-dependent reactions produce ATP and NADPH; the light-independent reactions use energy stored in ATP and NADPH. light reactions create ATP and NADPH --> calvin cycle create NADP+ and ADP

Which of the following statements best helps explain the reaction specificity of an enzyme? The free energy of the reactants is greater than the free energy of the products. The equilibrium constant of the reaction is much greater than 1. The shape and charge of the substrates are compatible with the active site of the enzyme. The concentration of the enzyme inside living cells is greater than the concentration of substrate.

The shape and charge of the substrates are compatible with the active site of the enzyme. In order to make a functional enzyme substrate complex, the substrate must fit (lock and key) into the enzyme.

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.

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, 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 man interested in losing weight and increasing his fitness followed a strict diet and exercise regimen for three months. Body fat analysis indicated that the man had lost 7 kg (about 15 pounds) of fat by following this exercise and diet program. What is the most likely form by which the fat left his body? a. It was released as CO2 and H2O. b. It was converted to heat, which was released to the environment. c. It was broken down to amino acids and eliminated from the body. d. It was converted to ATP, which weighs much less than fat.

a. It was released as CO2 and H2O. products of cellular respiration since respiration increases when exercising bc more oxygen

Which kind of metabolic poison would most directly interfere with glycolysis? a. an agent that closely mimics the structure of glucose but is not metabolized b. an agent that binds to pyruvate and inactivates it c. an agent that reacts with oxygen and depletes its concentration in the cell d. an agent that reacts with NADH and oxidizes it to NAD+

a. an agent that closely mimics the structure of glucose but is not metabolized Glycolysis starts with glucose but if it cannot be metabolized, it cannot be broken down and perform respiration.

the synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of a. an endergonic reaction coupled to an exergonic reaction. b. allosteric regulation. c. active transport. d. a redox reaction.

a. an endergonic reaction coupled to an exergonic reaction. synthesis = building = endergonic oxidative phosphorylation = exergonic

In the presence of oxygen , the three carbon compound pyruvate can be catabolized in the citric acid cycle. First , however, the pyruvate 1)loses a carbon 2)is oxidized to form a two carbon compound , which 3) covalently bound to coenzyme A. these three steps result in the formation of

acetyl COa, NADH, H , CO2

Strenuous exercise lowers the blood pH, causing the curves for both hemoglobin and myoglobin to shift to the right. This shift results in

an unloading of O2 at higher partial pressures

A molecule that is phosphorylated a. has been reduced as a result of a redox reaction involving the loss of an inorganic phosphate. b. has increased chemical potential energy that may be used to do cellular work. c. has a decreased chemical energy and is less likely to provide energy for cellular work d. has been oxidized as a result of a redox reaction involving the gain of an inorganic phosphate.

b. has increased chemical potential energy that may be used to do cellular work. addition of phosphate group = synthesis = endergonic = increase energy

A noncompetitive inhibitor decreases the rate of an enzyme reaction by

changing the shape of the enzyme's active site

inside the active mitochondrion , most electrons follow which pathway

citric acid cycle - NADH - ETC - oxygen

in animal cells, glycolysis occurs in the

cytosol

Which of the following describes a metabolic consequence of a shortage of oxygen in muscle cells? a. No ATP production due to the absence of substrate-level phosphorylation b. A decrease in the oxidation of fatty acids due to a shortage of ATP c. An increase in blood pH due to the accumulation of lactic acid d. A buildup of lactic acid in the muscle tissue due to fermentation

d. A buildup of lactic acid in the muscle tissue due to fermentation shortage of oxygen = less respiration = more tired = more lactic acid

A young dog has never had much energy. He is brought to a veterinarian for help, and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can use only fatty acids and amino acids for cellular respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of the dog's condition? a. His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA. b. His cells cannot transport NADH from glycolysis into the mitochondria. c. His cells lack an essential enzyme in glycolysis so they cannot produce pyruvate. d. His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.

d. His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.

A chemical reaction that has a positive G best described as

endergonic

A type of anaerobic respiration that's purpose is to replenish NAD+ so that glycolysis can be continued. Produces either alcohol or lactic acid as a by product is... A. Fermentation B. Calvin Cycle C. Electron transport chain D. Glycolysis E. Krebs Cycle

fermentation = produces alcohol or lactic acid

where in the mitochondria is the enzyme ATP Synthase localized

inner membrane

where are the proteins of the electron transport chain located

inner mitochondrial membrane

A severe fever can result in death if not brought under control because

it may alter the tetiary structure of cellular enzymes

ATP serves as a common energy source for organisms because

its energy can be easily transferred to do cellular work

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. Graph 1. Effect of pH on peroxidase activity *peroxidase activity is greatest at 5 and decreases from there on If the experiment is repeated at pH 11, the observed activity level of the enzyme will most likely be

lower than the level at pH 9

According to the data, the crickets at 25oC have greater oxygen consumption per gram of tissue than do the crickets at 10oC. This trend in oxygen consumption is the opposite of that in the mice. The difference in trends in oxygen consumption among crickets and mice is due to their

mode of internal temperature regulation

what is the source of oxygen used to form water in the complete reactions of cellular respiration

molecular o2 oxygen is reduced

A student runs an experiment to test enzyme activity using catalase and peroxide. They soaked disks in catalase and timed how long it took to float in various concentrations of hydrogen peroxide. What do you predict the time to float would be if you performed the same experiment with catalase that had been boiled before starting? A. more than 30 seconds B. 30 seconds C. 10 seconds D. 5 seconds E. less than 1 second

more than 30 seconds higher temperatures disrupt the shape of activite site, reducing its activity

If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citrate in the citric acid cycle shown

oxaloacetate will accumulate and citrate will decrease

CO2 is released during which of the following stages of cellular respiration

oxidation of pyruvate to acetyl CoA and the citric acid cycle

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is

oxygen

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, 6, 8, and 10) were prepared and added to separate test tubes. Hydrogen peroxide (H2O2) was added to each test tube. Yeast was added, and the reactions were timed. After 1 minute the amount of oxygen gas released was determined by measuring the foam layer produced in each test tube. Figure 1 illustrates the experimental setup. 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? A) pH 4 buffer solution and hydrogen peroxide only B) All five pH buffer solutions combined hydrogen peroxide only C) Water, hydrogen peroxide, and yeast D) Water and yeast only

pH 4 buffer solution and hydrogen peroxide only a control would have no reaction, so yeast wouldn't be added

Chlorophyll absorbs ________________ light A. red B. red and blue C. green D. green and blue E. green and red

red and blue chlorophyll absorbs everything but green light since it reflects that. absorbs red (long) and blue (short wavelength)

when a molecule of NAD+ gains a hydrogen atom (not a proton ) The NAD+ molecule becomes

reduced gaining hydrogen = reduction

most co2 from catabolism is released during

the citric acid cycle

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is

the creation of a proton motive force

To test the hypothesis that a particular plant synthesizes storage lipids by using glyceraldehyde 3-phosphate (G3P) from photosynthesis, a researcher plans to use radiolabeled precursors to track the molecules through the biosynthetic pathway. Which of the following radiolabeled precursors is most appropriate for the researcher to use? A. 15N-labeled N2, because atmospheric nitrogen is fixed to amino acids by photosynthesis B. 32P-labeled phosphate, because lipids are stored in plants as phospholipids C. 14C-labeled CO2, because atmospheric carbon is fixed to carbohydrates by photosynthesis D. 35S-labeled methionine, because amino acids are incorporated into lipids during photosynthesis

14C-labeled CO2, because atmospheric carbon is fixed to carbohydrates by photosynthesis precursors = reactants co2 is the only option that is an actual reactant for photosynthesis and can be used to track the pathway

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. A substance that removes carbon dioxide gas B. A plant to produce oxygen C. A glucose reserve D. A valve to release excess water

A substance that removes carbon dioxide gas to measure oxygen consumption, oxygen has to be isolated out. therefore, co2 has to be removed

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? A) Function will be disrupted by adding the urea and regained by removing the urea. B) Function will be disrupted by adding the urea, but it will not be regained by removing the urea. C) Function will be gained by adding the urea and disrupted by removing the urea. D) Function will be unaffected by the addition and removal of the urea.

A) Function will be disrupted by adding the urea and regained by removing the urea. disrupted secondary and tertiary when urea was added regained secondary and tertiary when urea was removed

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, the researcher will measure the rate of product formation. A) It will provide a measurement of product formation in the absence of the substrate B) It will provide a measurement of product formation in the presence of a denatured enzyme C) It will show the effect of doubling the amount of substrate on the rate of product formation D) It will show the effect of increased enzyme activity on the rate of product formation

A) It will provide a measurement of product formation in the presence of a denatured enzyme Tube V has all boxes checked so it will measure the effect of product formation

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. *difference in group 1 and 2 is that 1 has actively reproducing bacteria while group 2 has heat-killed bacteria Which of the following statements best helps justify the inclusion of group 2 as one of the controls in the experiment? A) It will show whether the changes observed in group 1 depend on the metabolic activity of soil bacteria. B) It will show whether the changes observed in group 1 depend on the type of plants used in the experiment. C) It will show the average growth rate of seedlings that are maintained in a nonsterile environment. D) It will show the changes that occur in the roots of seedlings following an infection by soil bacteria.

A) It will show whether the changes observed in group 1 depend on the metabolic activity of soil bacteria. heat killed = dead = no metabolic activity

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. Graph 1. Relative activity of pepsin, trypsin, and chymotrypsin at pH 0 through 11 Which of the following best predicts how the structure and function of pepsin will change as it enters the small intestine? A) Pepsin will not change in shape and will continue to break down proteins in the small intestine. B) It contains hydrogen atoms. C) It is an ionic compound. D) It forms hydrogen bonds.

A) Pepsin will change in shape because of the basic environment of the small intestine; therefore, its enzymatic activity will decrease. According to the graph, enzyme activity actually increases as pepsin goes from pH of 2 to 8 so breakdown will continue to happen.

To study the effects of catalase on its substrate, hydrogen peroxide, students made solutions of different hydrogen peroxide concentrations. The activity of the enzyme was measured by the amount it took for disks covered in catalase to convert the hydrogen peroxide to oxygen and water and float to the surface on the bubbles. *Graph shows that as hydrogen peroxide concentration increases, the time it takes for disks to float decreases Which of the following experimental designs should be used as a control? A) Place a catalase-soaked disk in a beaker of water B) Drop the disks from different heights into the solution C) Poke the floating disks back down to the bottom of the beaker and retime the rise of the disks D) Shake the beakers during the time the disks are rising E) Dip the disks in the 5% solution before putting them in any other solution

A) Place a catalase-soaked disk in a beaker of water A beaker of water has no hydrogen peroxide, so it serves as control.

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. Which of the following statements correctly explains the observed effect of the acetylcholine concentration on the rate of the enzyme-catalyzed reaction? A) The active site of AChE is specific for acetylcholine, and only one substrate molecule can occupy the active site at a time. B) AChE begins converting product into substrate as the acetylcholine concentration changes from low to high. C) The AChE protein becomes denatured as the acetylcholine concentration changes from low to high. D) The substrate specificity of AChE changes as the acetylcholine concentration changes from low to high

A) The active site of AChEAChE is specific for acetylcholine, and only one substrate molecule can occupy the active site at a time. If it is one at a time, then reaction rate is slower at higher substrate concentrations and faster at lower substrate concentrations.

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? A) The initial concentration of the substrate B) the final concentration of the product C) the three-dimensional structure of the enzyme D) the temperature of the aqueous buffer solution

A) The initial concentration of the substrate Everything changes but that. The final concentration of product is DV, so that changes. Enzyme structure changes under temperature and temperature is the IV so that changes.

A researcher claims that some bacteria contain things the change the function of a particular enzyme. To test this, they will grow 2 different bacteria in separate cultures and isolate the contents of the cells from each. They will add different combinations of cell contents, substrate, and enzyme to test tubes at the optimal pH for the enzyme and then measure the rate of product formation. Which of the following statements best justifies the inclusion of test tubes 3 and 7 in the experiment? term-31 *Tube 3 and 7 have no enzyme added. A) They will show whether the isolated cellular contents have enzymatic activity B) They will show whether environmental pH affects the functioterm-9n of the enzyme C) They will show the rate of product formation in the absence of bacterial factors D) They will show the rate of product formation in the absence of the substrate

A) They will show whether the isolated cellular contents have enzymatic activity. Isolated = nothing

The energy required to run the Calvin cycle reactions of photosynthesis comes from which two substances produced during the light-dependent reactions? A. ADP and PO4 B. H+ and PO2 C. O2 and CO2 D. H2O and CO2 E. ATP and NADPH

ATP and NADPH calvin oxidizes ATP and NADPH from light dependent reactions to reduce co2 → build organic molecules

A researcher claims that the synthesis of ATP from ADP and inorganic phosphate (Pi) is essential to cellular function. Which of the following statements best helps justify the researcher's claim? A. ADP is a small molecule that some cells release into their environment as a way of communicating with other cells. B. ATP hydrolysis is an energy-releasing reaction that is often coupled with reactions that require an input of energy. C. Inorganic phosphate(Pi) is a substance that cells typically acquire from their environment. D. ATP synthase is a mitochondrial enzyme that catalyzes the conversion of ADP and Pi to ATP.

ATP hydrolysis is an energy-releasing reaction that is often coupled with reactions that require an input of energy. In order for ATP to convert to ADP (hydrolysis), one phosphate group must be broken, therefore releasing energy. breakdown = exergonic

Figure 1. ATP production by three metabolic pathways following the start of an intense period of exercise. Which of the following correctly uses the data to justify the claim that the phosphagen system is an immediate, short-term source of ATP for muscle cells?

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

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 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? A. Light-capturing pigment molecules in green plants absorb red, blue, and violet light but reflect green light. B. The energy of a photon of light is proportional to its frequency and inversely proportional to its wavelength. C. As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat. D. Captured energy is stored in the molecular bonds of organic molecules, including simple sugars and starch.

As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat. Not all light energy is used in photosynthesis

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? A. Atmospheric carbon dioxide is produced by the burning of fossil fuels, which are formed from the remains of living organisms such as plants. B. Atmospheric carbon dioxide is a byproduct of cellular respiration, which is a metabolic process that occurs in plants and other living organisms. C. Atmospheric carbon dioxide typically enters plant leaves through stomata, which plants rely on for regulating gas exchange with the atmosphere. D. Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds.

Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds. co2 is a reactant for photosynthesis to produce sugar in calvin cycle

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) The uncoupling protein in this tissue increases the production of ATP and causes more body heat to be produced to warm the animal. B) The uncoupling protein in this tissue reduces the proton gradient across the membrane and thus produces heat to warm the animal without ATP production. C) The uncoupling protein in this tissue causes an increase in the proton gradient, which causes more ATP to be produced that helps to warm the animal. D) The uncoupling protein in this tissue reduces the production of ATP and creates an increase in the proton gradient that allows more heat energy to be produced to warm the animal.

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

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 fterm-16or this experiment? A) A test tube containing no camera film B) A test tube containing only a piece of exposed camera film C) A test tube containing a piece of exposed camera film submerged in water D) A test tube containing a piece of exposed camera film and all three enzyme solutions

C) A test tube containing a piece of exposed camera film submerged in water The IV are the enzyme solutions, so the control would be where there is no enzyme solution. Therefore, it would just have a camera film.

In an experiment, a scientist isolates mitochondria from living cells and suspends them in two different buffered solutions. One solution is maintained at pH 4, while the other solution is maintained at pH 9. The scientist finds that mitochondria in the solution at pH 4 continue to produce ATP but those in the pH 9 solution do not. The results of the experiment can be used as evidence in support of which of the following scientific claims about mitochondrial activity? A) Mitochondria in a cell-free environment are unable to convert thermal energy into ATP. B) The electron transport chain pumps electrons from the cytosol to the mitochondrial matrix. C) ATP production in mitochondria requires a hydrogen ion gradient that favors movement of protons into the mitochondrial matrix. D) ATP synthase molecules change their orientation in relation to the proton gradient across the mitochondrial membrane.

C) ATP production in mitochondria requires a hydrogen ion gradient that favors movement of protons into the mitochondrial matrix. A is wrong because mitochondria are found in cells. B is wrong cause only glycolysis takes place in cytosol.

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? A) The amount of product will decrease until the reaction rate goes to zero. B) The amount of product will decrease until the reaction reaches its equilibrium point or until the enzyme is been used up by the reaction. C) The amount of product will increase until the reaction reaches its equilibrium point or until the substrate is used up by the reaction. D) The amount of product will increase without stopping because the enzyme will be unchanged by the reaction.

C) 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 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? A) Yeast cells produce protein kinases, which are enzymes that catalyze the transfer of phosphate groups from ATP to protein substrates. B) Yeast cells produce DNA polymerases, which are enzymes that catalyze the conversion of free nucleotides into strands of DNA. C) Yeast cells produce invertase, which is an enzyme that catalyzes the conversion of the disaccharide sucrose into glucose and fructose. D) Yeast cells produce catalase, which is an enzyme that catalyzes the conversion of hydrogen peroxide into water and oxygen gas.

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

The process that uses ATP and NADPH to power the fixation of carbon into sugars. A. Light Reactions B. Calvin Cycle C. Granum D. Krebs Cycle E. Electron transport chain

Calvin Cycle calvin cycle turns carbon dioxide into sugars. it oxidizes ATP and NADPH from light reactions to create ADP and NADP+

Alcohol dehydrogenase (ADH) is an enzyme that aids in the decomposition of ethyl alcohol (C2H5OH) into nontoxic substances. Methyl alcohol acts as a competitive inhibitor of ethyl alcohol by competing for the same active site on ADH. When attached to ADH, methyl alcohol is converted to formaldehyde, which is toxic in the body. Which of the following statements best predicts the effect of increasing the concentration of substrate (ethyl alcohol), while keeping the concentration of the inhibitor (methyl alcohol) constant?

Competitive inhibition will decrease because the proportion of the active sites occupied by substrate will increase. Substrate (ethyl) increases while inhibitor (methyl) stays the same, so the competitive inhibition (methyl) decreases.

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? A) A hydrophilic molecule interacts with nonpolar side chains in the enzyme's active site. B) A hydrophobic molecule interacts with polar side chains in the enzyme's active site. C) A molecule with positive charges interacts with positively charged side chains in the enzyme's active site. D) A molecule with negative charges interacts with positively charged side chains in the enzyme's active site.

D) A molecule with negative charges interacts with positively charged side chains in the enzyme's active site. Enzyme substrate complex forms when there are positive charges along the active site and negative charged on the substrate.

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? A) Some antibiotics inhibit the synthesis of bacterial cell walls. B) Some antibiotics inhibit protein synthesis in bacteria cells. C) Some plasmids cannot exist in a bacterial cell with certain other plasmids. D) Some plasmids contain antibiotic resistance genes

D) Some plasmids contain antibiotic resistance genes. observation: bacteria contains plasmids that are resistant claim: genetic variation provides organisms the ability to survive and reproduce plasmids contain genes that are antibiotic resistant

If an individual with diabetes consumes food that is high in simple carbohydrates, blood-sugar levels can rise above normal levels. Which of the following questions would provide the best direction for a researcher who wanted to study the impact of abnormally high blood-sugar levels on cellular homeostasis in diabetics? A. Are cells in diabetics larger in size than those in nondiabetics? B. Do the cells in diabetics have more potassium ion channels in the cell membrane than the cells in nondiabetics do? C. Does water move from cells into blood vessels more rapidly in diabetics than in nondiabetics when blood-sugar levels are higher than normal? D. Do the cells of diabetics use simple sugars as an energy source?

Does water move from cells into blood vessels more rapidly in diabetics than in nondiabetics when blood-sugar levels are higher than normal? sugar is being products since the levels rise to synthesize, the body needs water and carbs

New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and find it difficult to continue exercising. These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise. Which of the statements below is the best explanation of why athletes would need to monitor lactate levels? a. During aerobic respiration, muscle cells cannot produce enough lactate to fuel muscle cell contractions and muscles begin to cramp, thus athletic performance suffers. b. During fermentation muscle cells receive too little pyruvate, thus athletes experience cramping and fatigue. c. During aerobic respiration, muscles cells produce too much lactate which causes a rise in the pH of the muscle cells, thus athletes must consume increased amounts of sports drinks, high in electrolytes, to buffer the pH. d. During fermentation lactate levels increase, which indicates insufficient oxygen is reaching the muscles causing athletic performance to suffer.

During fermentation lactate levels increase, which indicates insufficient oxygen is reaching the muscles causing athletic performance to suffer. lactic acid is associated with fermentation because the body is tired and doesn't produce enough oxygen

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.

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? A. Elysia chlorotica will die if not exposed to light. B. Elysia chlorotica grows when exposed to light in the absence of other food sources. C. Elysia chlorotica grows faster when exposed to light than when placed in the dark. D. Elysia chlorotica grows in the dark when food sources are available.

Elysia chlorotica grows when exposed to light in the absence of other food sources. when exposed to sunlight, photosynthesis occurs. otherwise, the sea slug receives food via cellular respiration

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

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?

Glucose has the right shape and charge to cause hexokinase to undergo a structural change needed for catalysis, whereas water does not. Water leads to the wrong process. Hexokinase wants to turn glucose to glucose-6-phosphate, not ATP hydrolysis.

Which metabolic process is common to both aerobic cellular respiration and alcoholic fermentation?

Glycolysis

Phosphofructokinase (PFK) is an enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate during glycolysis, as represented in Figure 1. 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.

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the

H + concentration gradient across the membrane holding the ATP synthase

The O2 released during photosynthesis comes from A. H2O B. NADPH C. RuBP (RuDP) D. C6H12O6 E. CO2

H2O h2o is oxidized into h and o during light reactions and oxygen is released as a waste product

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.

Which of the following questions will best direct an investigation of the mechanism of ATP synthase? A. What is the source of the inorganic phosphate that is used to generate ATP from ADP? B. Is the phosphorylation of ADP by ATP synthase dependent on the formation of a proton gradient? C. Can ATP synthase use the energy released by phosphorylation of ADP to pump protons against a concentration gradient? D. Can oxidative phosphorylation be uncoupled from the electron transport chain?

Is the phosphorylation of ADP by ATP synthase dependent on the formation of a proton gradient? atp synthase involves moving h+ ions back into the matrix to create atp hydrogen ions go down concentration gradient

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? A) It changes the shape and charge of the substrate so that it becomes more compatible with ALAD's active site. B) It changes the amino acid sequence of the ALAD protein so that the enzyme catalyzes a different reaction. C) It changes the three-dimensional structure of the active site so that ALAD is no longer compatible with its substrate. D) It changes the enzyme-substrate complex so that the transition state is more stable and the reaction proceeds at a faster rate.

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

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? a. It increases the surface area for oxidative phosphorylation. b. It increases the surface area for glycolysis. c. It increases the surface area for substrate-level phosphorylation. d. It increases the surface area for the citric acid cycle.

It increases the surface area for oxidative phosphorylation. oxidative phosphorylation is found in the inner mitochondrial membrane

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. Which of the following statements best helps justify the inclusion of test tube 5 in the experiment? A) It will act as a control for test tube 4 by showing the effect of the presence or absence of the substrate. B) It will act as a control for test tube 4 by showing the effect of a change in environmental temperature. C) It will act as a control for test tube 6 by showing the effect of the presence or absence of the enzyme. D) It will act as a control for test tube 6 by showing the effect of a change in sodium chloride concentration.

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

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 best justifies the inclusion of test tube V as a control in the experiment? A) It will provide a measurement of amylase activity at an acidic pH B) It will provide a measurement of amylase activity at a basic pH C) It will show the color change that occurs in the absence of enzyme activity D) It will show the color change that occurs in the absence of the amylase protein

It will show the color change that occurs in the absence of enzyme activity At test tube V, the pH is 7 so A and B are wrong. At V, there is an amylase added, so D is wrong.

_______ finishes breaking down Acetyl CoA to create ATP and NADH. A. Fermentation B. Link Reaction C. Oxidative Phosphorylation D. Glycolysis E. Krebs Cycle

Krebs Cycle acetyl coA is produced from glycolysis which drives Krebs which creates ATP and NADH as byproducts

______ uses light energy to excite electrons in photosystem I and II, split water, and create ATP and NADPH. A. Fermentation B. Calvin Cycle C. Electron transport chain D. Glycolysis E. Light Reactions

Light Reactions

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.

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, the researchers added a hydrogen peroxide solution containing guaiacol to several identical test tubes and adjusted the solution in each test tube to a different pH. The researchers included the guaiacol because it caused the solutions to change color as the reactions proceeded, which the researchers relied on for measuring reaction rates. Finally, the researchers added the same amount of peroxidase to each test tube and measured the rate of each reaction at 23°C. The results of the experiment are represented in Figure 1. 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 can be used to determine the rate of enzyme-catalyzed reactions? Rate of disappearance of the enzyme Rate of disappearance of the substrate Rate of disappearance of the product Change in volume of the solution Increase in activation energy

Rate of disappearance of the substrate The substrate is what goes into the enzyme. When the enzyme binds to the substrate, it forms the enzyme-substrate complex so the substrate disappears to form the product.

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, salivary amylase, and arginase. The results of the experiment are represented in Figure 1. Figure 1. The effect of pH on three different enzymes Which of the following actions will provide the most appropriate negative control for the experiment?

Repeating the experiment with denatured enzymes