UNIT 3
The mean map distance between gene R and gene L is closest to which of the following?
28 map units
The mean number of fruit flies per student that are homozygous recessive for both genes is closest to which of the following?
29.0
How many degrees of freedom should be used when looking up the critical value for a chi-square analysis of the ratios of phenotypes observed among the F2 offspring versus the expected phenotypic ratio assuming independent assortment?
3
How many reduced dinucleotides would be produced with four turns of the citric acid cycle?
4 FADH2 and 12 NADH
If the woman and a man with normal clotting function have children, what is the probability of their children exhibiting hemophilia A?
50 percent for sons, 0 percent for daughters
Each time a molecule of glucose (C6H12O6 ) is completely oxidized via aerobic respiration, how many oxygen molecules (O2 ) are required?
6
Which of the following is closest to the calculated chi-square (χ2) value for the data presented in Table 1?
72.01
Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6 ) in cellular respiration?
76
Process found in both photosynthesis and cellular respiration
Chemiosmosis
Which test tubes are controls in the experiment?
Test tubes 1, 3, 5, and 7
When oxygen is released as a result of photosynthesis, it is a by-product of which of the following?
splitting the water molecules
The ATP made during fermentation is generated by which of the following?
substrate-level phosphorylation
What is the primary function of the Calvin cycle?
synthesize simple sugars from carbon dioxide
In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis translocates protons from
the stroma to the thylakoid space
Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?
the synthesis of ATP
Where are the molecules of the electron transport chain found in plant cells?
thylakoid membranes of chloroplasts
The students plan to use a significance level of p=0.01. Which of the following is the most appropriate critical value for the students to use in their chi-square goodness-of-fit test?
11.34
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?
14C-labeled CO2, because atmospheric carbon is fixed to carbohydrates by photosynthesis
Based on the data, the percent of the mitotic cells that were in metaphase is closest to which of the following?
18%
How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate?
2
Based on Table 1, what percent of the life cycle of yeast cells is spent in DNA replication?
25 percent
Which of the following steps in a signaling pathway typically occurs first once a chemical messenger reaches a target cell?
A ligand binds to a receptor.
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 molecule with negative charges interacts with positively charged side chains in the enzyme's active site.
What wavelength of light in the figure is most effective in driving photosynthesis?
A) 420 mm
What does the chemiosmotic process in chloroplasts involve?
A) establishment of a proton gradient
Where does the Calvin cycle take place?
A) stroma of the chloroplast
The ATP made during glycolysis is generated by
A) substrate-level phosphorylation.
The energy required to run the Calvin cycle reactions of photosynthesis comes from which two substances produced during the light-dependent reactions?
ATP and NADPH
Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
ATP and NADPH
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?
ATP hydrolysis is an energy-releasing reaction that is often coupled with reactions that require an input of energy.
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.
For this condition, which of the following modes of inheritance is most consistent with the observations?
Autosomal dominant
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?
ATP production in mitochondria requires a hydrogen ion gradient that favors movement of protons into the mitochondrial matrix.
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.
In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of
ATP, CO2 , and ethanol (ethyl alcohol).
Which of the following is most likely the immediate cause of the first appearance of Huntington's disease in a person?
An allele with more than 39 CAG repeats was inherited by the affected person.
Which of the following statements best justifies the claim that changes in the expression of ced−9 in C. elegans can affect regulation of apoptosis in the cell?
An experiment showed that a mutation in the ced−9ced−9 gene led to excessive cell death in C. elegans.
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.
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?
Atmosphere carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds
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.
Which of the following graphs best represents data from the experiment that will support the researcher's claim?
B
Which of the following tables best shows the expected values in the F2 generation for a chi-square goodness-of-fit test for a model of independent assortment?
B
In glycolysis, for each molecule of glucose oxidized to pyruvate
B) 2 molecules of ATP are used and 4 molecules of ATP are produced.
Photorespiration lowers the efficiency of photosynthesis by preventing the formation of
B) 3-phosphoglycerate molecules
Energy released by the electron transport chain is used to pump H+ ions into which location?
mitochondrial intermembrane space
Why are C4 plants able to photosynthesize with no apparent photorespiration?
B) They use PEP carboxylase to initially fix CO2 .
The oxygen consumed during cellular respiration is involved directly in which process or event?
B) accepting electrons at the end of the electron transport chain
The primary role of oxygen in cellular respiration is to
B) act as an acceptor for electrons and hydrogen, forming water.
Which of the following is likely to lead to an increase in the concentration of ATP in a cell?
B) an increase in a cell's catabolic activity
The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction
B) loses electrons and loses energy.
What is proton-motive force?
B) the transmembrane proton concentration gradient
During cellular respiration, acetyl CoA accumulates in which location?
mitochondrial matrix
What are the products of linear photophosphorylation?
C) ATP and NADPH
When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a hydrogen ion) the molecule becomes
C) reduced.
Figure 10.1 shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?
D) Other pigments absorb light in addition to chlorophyll a.
Process in which CO2 is released as a by-product of oxidation-reduction reactions
Calvin cycle (light-independent reactions of photosynthesis)
Which of the following justifies the claim that differences in components of cell signaling pathways explain the different responses to epinephrine?
Cell signaling depends on the ability to detect a signal molecule. Not all cells have receptors for epinephrine. Only cells with such receptors are capable of responding.
Which of the following best describes the role of cell-to-cell communication during a response to an invasion of antigens?
Chemicals that are secreted from antigen-presenting cells then activate helper T cells.
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
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.
The reactions of glycosis occur in the
Cytosol
In a plant cell, where are the ATP synthase complexes located?
D) A and C....thylakoid membrane & plasma membrane
Which statement describes the functioning of photosystem II?
D) The electron vacancies in P680 are filled by electrons derived from water.
Which of the following is an example of potential rather than kinetic energy?
D) a food molecule made up of energy-rich macromolecules
In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + Pi to ATP?
D) energy released from movement of protons through ATP synthase
Which metabolic pathway is common to both cellular respiration and fermentation?
D) glycolysis
Which statement best predicts why a cell's progression through the cell cycle might be halted at the G1/S checkpoint?
Damage occurred to DNA when it was being copied in G1.
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?
Based on Figure 1, which of the following questions could best be addressed?
Does synapsis of homologous chromosomes in the parent cell contribute to an increase in genetic diversity in the daughter cells?
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?
Does water move from cells into blood vessels more rapidly in diabetics than in nondiabetics when blood-sugar levels are higher than normal?
The chemical reaction for photosynthesis is 6 CO2 + 12 H2O + light energy -> C6H12O6 + 6 CO2 + 6 H20 If the input water is labeled with a radioactive isotope of oxygen, 180, then the oxygen gas released as the reaction proceeds is also labeled with 180. Which of the following id the most likely explaination?
During the light reactions of photosynthesis, water is split, removing electrons and protons, and oxygen gas is released.
During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?
E) FADH2
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?
Elysia chlorotica grows when exposed to light in the absence of other food sources.
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
Warfarin is a drug used to treat certain blood clots. Warfarin blocks the formation of the active form of vitamin K-dependent clotting factors. Based on the model, which of the following best predicts the effects of warfarin on a patient?
Factor X will not be activated, which will prevent thrombin from forming.
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.
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.
Process in which sugar is oxidized to pyruvic acid
Glycolysis
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 O2 released during photosynthesis comes from
H20
Which of the following sequences correctly represents the flow of electrons during photosynthesis?
H2O → NADPH → Calvin cycle
Which of the following best predicts the effect of the chromosomal segregation error shown in Figure 1?
Half of the resulting gametes will have the correct number of chromosomes, and the other half will have an incorrect number of chromosomes.
Which of the following best explains a distinction between metaphase I and metaphase II?
Homologous pairs of chromosomes are aligned during metaphase I, but individual chromosomes are aligned during metaphase II.
Which statement provides the evidence to justify the claim that signal transduction may result in an altered phenotype?
If the SRY gene is absent or nonfunctional, the embryo will exhibit female sexual development.
Which of the following best predicts what will happen to the blood glucose level if the person has another meal at 5 p.m.?
Immediately after the meal, the blood glucose level will increase, and then insulin will be secreted to counter the increase.
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 best predicts the effect of a mutation that causes EGFR to be active in the absence of a growth factor?
Increased cell division will lead to the formation of a tumor.
Which of the following questions will be 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?
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?
A compound that prevents the separation of the homologous chromosomes in anaphase I is being studied. Which of the following questions can be best answered during this study?
Is there a pattern to the movement of homologous chromosomes in the presence of this compound?
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?
It changes the three-dimensional structure of the active site so that ALAD is no longer compatible with its substrate.
Which of the following best describes an advantage of the phenotypic plasticity displayed by the tadpoles?
It gives the tadpoles increased versatility with respect to diet.
Which of the following best describes the component that metformin represents in a signal transduction pathway that regulates glucose production in the liver?
It is a ligand that activates the signal transduction pathway of the activation of AMPK.
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.
Process in which carbon from CO2 is incorporated into organic molescules
Krebs cycle (citric acid cycle)
Which of the following best explains how the leaves from the same plant can have different stomatal densities when exposed to an elevated carbon dioxide level?
Leaf growth is promoted through increased photosynthesis, but the genetically regulated rate of stomatal production is not altered, leading to a decrease in stomatal density.
Process in which O2 is released as a by-product of oxidation-reduction reaction
Light-dependent reactions of photosynthesis
Which of the following best explains how the sweet pea plants in the parental generation produce F1 offspring with 14 chromosomes?
Meiosis I and II lead to the formation of cells with 7 chromosomes. During meiosis II, homologous chromosomes separate. During meiosis II, sister chromatids separate. Two cells combine during fertilization to produce offspring with 14 chromosomes.
Based on the sample means, which of the following conclusions about the cells in the growing root tips of Zea mays seedlings is best supported by the results of the experiment?
More cells are produced per unit of time in the root tips growing in compact sand than in the root tips growing in loose sand.
An intermediate electron acceptor for oxidation that occur in both glycolysis and Krebs cycle reactions
NAD+
Which of the following statements describes NAD+
NAD+ is reduced to NADH during both glycolysis and the citric acid cycle.
In addition to ATP, what are the end products of glycolysis?
NADH and pyruvate
Oxygen consumption can be used as a measure of metabolic rate because oxygen is
Necessary for ATP synthesis by oxidative phosphorylation
A researcher found a mutation that resulted in the PFK enzyme being unable to bind ATP to the allosteric site. Which of the following best predicts the effect of the mutation?
Negative feedback regulation does not occur, so the enzyme will be active when glycolysis is not needed.
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.
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.
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 statements best describes the relationship between photosynthesis and respiration?
Photosynthesis stores energy in complex organic molecules, while respiration releases it.
Which of the following best predicts the effect of adding this inhibitor to a culture of plant cells?
Plant cells will be unable to perform glycolysis due to the inhibitor and will die.
Carbohydrate-synthesizing reactions of photosynthesis directly require
Products of the light reactions
Two types of these molecules are produced from glucose during glycolysis
Pyruvate
Which of the following can be used to determine the rate of enzyme-catalyzed reactions?
Rate of disappearance of the subtrate
Which of the following actions will provide a negative control for the investigation?
Repeating the experiment using heat-denatured peroxidase
Which of the following actions will provide the most appropriate negative control for the experiment?
Repeating the experiment with denatured enzymes
For sexually reproducing diploid parent cells, which of the following statements best explains the production of haploid cells that occurs in meiosis but not in mitosis?
Separation of chromatids occurs once, and there are two rounds of cell division in meiosis.
Which of the following most accurately describes an observation and an effect of the viral infection indicated by the data in Table 1?
Seventy-five percent of the virus-infected cells are found in mitosis. The virus stimulates frequent cell division.
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.
Based on Figure 1, which of the following statements correctly links a stage of the cell cycle with the event occurring at that stage?
Synthesis of sufficient DNA for two daughter cells occurs in stage II
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?
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.
In addition to be the pigments commonly associated with photosynthesis, a certain photosynthesis 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 photosynthesis species are?
The additional pigments allow the species containing them to harvest energy from wavelengths of light that the other photosynthetic species cannot use
Based on the data in Figure 1, which of the following is the best prediction of the mode of inheritance of red eyes in Japanese koi?
The allele for red eyes is inherited in an autosomal dominant pattern.
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.
The researchers calculated a chi-square value of 29.25. If there are three degrees of freedom and the significance level is p=0.05, which of the following statements best completes the chi-square test?
The critical value is 7.82, and the null hypothesis can be rejected because the calculated chi-square value is greater than the critical value.
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?
The dilution of ammonia by direct excretion into freshwater conserves energy.
Which of the following statements best explains how the fur color can be different in Himalayan rabbits raised under different temperature conditions?
The environment determines how the genotype is expressed.
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.
One of the researchers proposes using oxygen gas production to measure reaction rates. Which of the following statements best justifies the use of the proposed modification as a way of creating an appropriate control for the investigation?
The experiment can be repeated without guaiacol, which will reveal the effect of guaiacol on the reaction rates.
The sugar that results from three "turns" of the Calvin cycle is glyceraldehyde-3-phosphate (G3P). Which of the following is a consequence of this?
The formation of starch in plants involves assembling many G3P molecules, with or without further rearrangements.
Which of the following best explains a possible mechanism that would enable the hormone to efficiently reach all of the target cells in the body?
The hormone is released into the bloodstream where it can be transported to all cells with the correct receptors.
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
Which of the following changes in the FGFR signaling pathway is most likely to result in uncontrolled cell proliferation?
The irreversible association of FGFRFGFR proteins
Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?
The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, Pi , and NADP+ to the light reactions
Which of the follow indicates the mean number per cross of F2 plants producing medium-red grain and correctly explains the distribution of the phenotypes?
The mean number of medium-red phenotypes per cross is 20.8. The distribution of phenotypes suggests that multiple genes are involved in grain color determination.
Which of the following outcomes will most likely result from the inactivation of the beta-2 adrenergic receptor?
The rate of glycogen synthesis in the cell will increase.
Which of the events listed below occur in the light reactions of photosynthesis?
light is absorbed and funneled to reaction-center chlorophyll a.
Which of the following statements best helps explain the reaction specificity of an enzyme?
The shape and charge of the substrate are compatible with the active site of the enzyme
Which of the following statements best predicts the effect of a loss of function of the insulin receptor's intracellular domain?
The storage of GLUT4 in vesicles inside the cell will increase.
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
Which of the following statements is consistent with the data in Figure 1?
There is a change from 3 to 6 picograms of DNA because DNA is replicated before each round of cell division.
Which of the following statements best describes a primary function of plasmodesmata?
They allow the movement of molecules from one cell to another, enabling communication between cells.
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.
P680+ is said to be the strongest biological oxidizing agent. Why?
This molecule results from the transfer of an electron to the primary electron acceptor of photosystem II and strongly attracts another electron
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
Which of the following will most likely result from a loss of p53 function?
Uncontrolled cell proliferation
Which of the following questions would be most useful to researchers trying to determine the role of meiosis in the F2 phenotypic frequencies?
What is the recombination frequency between the genes for petal shape and pollen shape?
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.
Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon (CO2 ) from one molecule of pyruvate?
acetyl CoA
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
. Synthesis of ATP by the chemiosmotic mechanism occurs during
both photosynthesis and respiration.
Generation of proton gradients across membranes occurs during
both photosynthesis and respiration.
Which of the following describes a critical role of cAMP during the transduction stage of a G protein signal transduction pathway?
cAMP results in the activation of an enzyme that amplifies the signal by acting on many substrate molecules.
Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
catabolism
Cellular respiration harvests the most chemical energy from which of the following?
chemiosmotic phosphorylation
Inside an active mitochondrion, most electrons follow which pathway?
citric acid cycle → NADH → electron transport chain → oxygen
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 gradient.
As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find 30,000 molecules of ATP consumed, but only 20,000 molecules of NADPH. Where did the extra ATP molecules come from?
cyclic electron flow
Where does glycolysis takes place?
cytosol
Where are the proteins of the electron transport chain located?
mitochondrial inner membrane
CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they
fix CO2 into organic acids during the night.
During aerobic respiration, electrons travel downhill in which sequence?
food → NADH → electron transport chain → oxygen
Which of the following normally occurs whether or not oxygen (O2 ) is present?
glycolysis
Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?
glycolysis
In the thylakoid membranes, what is the main role of the antenna pigment molecules?
harvest photons and transfer light energy to the reaction-center chlorophyll
A molecule that is phosphorylated
has an increased chemical reactivity; it is primed to do cellular work
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
The splitting of carbon dioxide to form oxygen gas and carbon compounds occurs during
neither photosynthesis nor respiration
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
Reduction of NADP+ occurs during
photosynthesis.
During respiration, most ATP is formed as a direct result of the net movement of
protons down a concentration gradient
Which of the following are directly associated with photosystem I?
receiving electrons from plastocyanin
In the process of carbon fixation, RuBP attaches a CO2 to produce a 6 carbon molecule, which is then
regeneration of rubisco
