ap bio real study guide for midterm
Which of the following best describes the formation of the bond shown in Figure 1 ?
A covalent bond is formed between a carbon atom and a nitrogen atom along with the formation of H2OH2O .
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. hich 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
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.
Muscle contraction depends on ATP hydrolysis. During periods of intense exercise, muscle cells rely on the ATP supplied by three metabolic pathways: glycolysis, mitochondrial respiration, and the phosphagen system. Figure 1 shows the rates at which the three metabolic pathways produce ATP 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 or muscle cells?
ATP production by the phosphagen system increases and decreases rapidly following the start of the exercise period.
A study was conducted to understand the factors controlling the rate at which molecules or ions travel across cell membranes. An artificial membrane was created that was composed of a phospholipid bilayer only. The speed at which various substances crossed this membrane was measured. Some substances can pass through an actual cell membrane much faster than they passed through the artificial membrane in this study. Which of the following statements best explains this finding?
Actual cell membranes have a variety of proteins embedded in the membrane that are absent in the artificial membrane.
Which of the following best describes the numbered areas?
Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules.
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 magnesium sulfate solution taken orally can cause a net movement of water into the large intestine, which results from water molecules diffusing through aquaporins embedded in the cells of the intestinal lining. By which of the following mechanisms do the water molecules most likely move into the large intestine?
By passive transport from an area of low osmolarity to an area of high osmolarity
Aldosterone (a steroid hormone) is a small, nonpolar, hydrophobic molecule that enters a target cell by moving across the plasma membrane, down a concentration gradient. Based on the information presented, how does aldosterone most likely enter target cells?
By simple diffusion because aldersterone can enter a cell by moving across the plasma membrane and moving down the concentration gradient.
The cell membrane is selectively permeable due to its structure. Thus, the internal environment of the cell is distinct from the external environment of the cell. One biologist hypothesizes that small nonpolar molecules readily pass through the membrane. Another biologist alternatively hypothesizes that these types of molecules require channel and transport proteins that are embedded in the membrane in order to move across the membrane. Which of the following data would best refute this alternative hypothesis?
CO2 and N2 movement in and out of cells is unaffected when membrane protein activity is blocked.
Some cells, such as intestinal cells, exchange a lot of material with their surroundings. The surface-to-volume ratio of these cells affects the efficiency of material exchange. The table provides measurements of four different eukaryotic cells. Based on the data, which cell is likely to be most effective in the exchange of materials?
Cell 2
Researchers have proposed a model of chloroplast evolution. According to the model, chloroplasts evolved from a small prokaryotic organism that was engulfed by an ancestral eukaryote. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host. Which of the following observations best supports the model?
Chloroplasts and some prokaryotes share similar photosynthetic reactions.
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 ADHADH. 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 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.
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 ATPATP 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.
Figure 1 is a diagram of water molecules at the air-water interface at the surface of a pond.Based on Figure 1, which of the following best describes how the properties of water at an air-water interface enable an insect to walk on the water's surface?
Hydrogen bonds between molecules at the surface of the water provide surface tension, which allows the water surface to deform but not break under the insect.
Some viral infections can lead to the rupture of the lysosome membrane. Which prediction of the effect of this disruption of cellular compartmentalization is most likely correct?
Hydrolytic enzymes will be released, which will cause cell death.
Water is constantly diffusing into the cytosol of freshwater single-celled organisms. In order to maintain the proper solute concentrations in the cytosol, contractile vacuoles pump out the excess water. An experimenter placed single-celled organisms into various saline concentrations and recorded the ATP used by the contractile vacuole. The data are shown in the graph.Of the following, which additional investigation can be used to determine when the cells are in an isotonic solution?
Increasing the salinity of the environment a little at a time until the ATP usage reaches a minimum
The transport of a substance across a plasma membrane of a specific organelle requires energy. The rate at which the transport takes place also depends on temperature. A scientist isolated the specific organelle and then used the following treatments to determine the conditions that will result in the maximal transport. All treatments contained the extracted organelle and were maintained at 25°C The data from this experiment indicate that maximal rate of transport of protein X at 25°C occurs at an ATP concentration of 1.0μm/mL Which procedure should be done next to gather data needed to meet the scientist's objective?
Incubate samples containing 1.0μm/mL of ATP at four temperatures other than 25°C
Researchers investigate the transport of a certain protein into cells by endocytosis. In an experiment, the researchers incubate the cells in the presence of the protein and measure the amount of the protein that is absorbed into the cells over a five-minute period. Based on their observations, what should the researchers do to further clarify how the availability of the protein outside the cells affects the rate of endocytosis of the protein?
Incubate the cells in the presence of several different concentrations of the protein.
In an experiment, researchers compared the growth of two different plants, plant X and plant Y The researchers maintained the plants under nearly identical conditions and observed that plant X grew faster than plant Y. The researchers also observed that the inner mitochondrial membranes of plant X had more folds than did those of plant Y. Which of the following conclusions about increasing the number of folds in the inner mitochondrial membrane is best supported by the results of the experiment?
It increases the surface area available for ATP production, which results in faster cell growth.
Euglenids are single-cell eukaryotes that live in aquatic environments. The chloroplasts found inside euglenids are enveloped by three membranes, as represented in Figure 1. The inner membrane of euglenid chloroplasts resembles the thylakoid membrane. Figure 1. Simplified diagram of a euglenid, showing the structure of the chloroplast envelope Which of the following claims about the origin of the euglenid chloroplast is best supported by the three-membrane structure of the envelope?
It originated from the incorporation of a photosynthetic prokaryote into a eukaryotic cell by two endosymbiotic events.
Polypeptides are continuously being formed and degraded. One of these processes is shown. Which statement is the most accurate description of the reaction shown in Figure 1?
It represents a polypeptide chain that is broken down through a hydrolysis reaction.
In an experiment, researchers provided a radiolabeled amino acid to living plant cells. After one hour, the researchers determined the amount of the radiolabeled amino acid that was in each of several subcellular compartments. The results of the experiment are represented in the table. Which of the following conclusions about the radiolabeled amino acid is best supported by the results of the experiment?
It was mostly incorporated into proteins that regulate and manage metabolic reactions.
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. 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.
Amylase is a protein that catalyzes the conversion of starch to simple sugars. Amylase activity in an aqueous solution can be measured by using iodine as a starch indicator. A solution containing iodine and starch will have a dark-blue color, whereas a solution containing iodine but no starch will have a light-brown color. The color change of an iodine solution from dark blue to light brown can be used to measure the rate at which starch is converted to simple sugars. A student designs an experiment to investigate the effect of environmental pH on amylase function. The design of the experiment is presented in Table 1. Which of the following statements best justifies the inclusion of test tube VV as a control in the experiment?
It will show the color change that occurs in the absence of enzyme activity.
Figure 1. Change in energy over the course of four chemical reactions Based on the data in Figure 1, which of the following most likely represents the change in energy that occurs when ATP hydrolysis is coupled with the phosphorylation of a substrate?
Line 1 represents ATP hydrolysis, and line 4 represents phosphorylation of a substrate.
Which of the following observations best supports the claim that mitochondria evolved from once-free-living prokaryotic cells by the process of endocytosis?
Mitochondria are surrounded by a double membrane.
Which of the following conclusions is most clearly supported by the representations of nucleic acid #1 and nucleic acid #2 ?
Nucleic acid #1 contains adenine-thymine base pairs, whereas nucleic acid #2 does not.
The molecular structures of linoleic acid and palmitic acid, two naturally occurring substances, are shown in the figure.Based on the molecular structures shown in the figure, which molecule is likely to be solid at room temperature?
Palmitic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely together.
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.
The figure shows a representation of a protein embedded in a cell membrane. The numbers indicate different structural regions of the protein. Based on the figure, which of the following statements best describes the relationship between regions 1 and 2 of the protein?
Region 1 is hydrophilic because it interacts with an aqueous environment, whereas region 2 is hydrophobic because it interacts with the interior of the membrane.
Intravenous (IV) therapy is used for fluid replacement in instances of dehydration in humans and other animals. One type of IV fluid is essentially a saltwater solution. To determine the best concentration for therapy in people, a team of students is researching the effects of solutions of different salt concentrations on red blood cells. The following observations were made from three different red blood cell samples viewed under a microscope. The team wants to extend the research project. What should the team of students do next to obtain data that are more conclusive?
Repeat the process with other salt concentrations.
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. Which of the following actions will provide the most appropriate negative control for the experiment?
Repeating the experiment with denatured enzymes
Some membrane proteins help maintain the concentrations of ions inside a cell by transporting the ions across the cell's plasma membrane. Other membrane proteins form pores in the plasma membrane through which the ions can diffuse. A model showing the influence of membrane proteins on the movement of sodium (Na+) and potassium (K+) ions across a plasma membrane is presented in Figure 1. Based on the model presented in Figure 1, which of the following changes will most likely result from a depletion of available ATP stores inside the cell?
The Na+ concentration inside the cell will increase.
DNA and RNA are nucleic acids that can store biological information based on the sequence of their nucleotide monomers. Figure 1 shows a short segment of each of the two types of nucleic acids. Which of the following best describes a structural difference between DNA and RNA?
The backbone of DNA contains deoxyribose, whereas the backbone of RNA contains ribose.
The carbohydrates glucose, galactose, and fructose have the same chemical formula (C6H12O6) but different structural formulas, as represented in the figure.Which of the following statements about glucose, galactose, and fructose is most likely true?
The carbohydrates have different properties because they have different arrangements of carbon, hydrogen, and oxygen atoms.
Which of the following cellular deficiencies would most likely be related to mutations in mitochondrial proteins?
The cell is unable to complete reactions related to electron transport and ATP production.
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 is an accurate description of the process shown in Figure 1 ?
The formation of a covalent peptide bond in a dehydration synthesis reaction
The model below shows the structure of a portion of a plasma membrane in an animal cell.Which statement best explains the orientation of the phospholipid molecules in this model?
The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments.
Figure 1 represents a nucleic acid fragment that is made up of four nucleotides linked together in a chain.Figure 1. Nucleic acid fragment Which of the following characteristics of Figure 1 best shows that the fragment is RNA and not DNA?
The identity of each nitrogenous base
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 best describes how amino acids affect the tertiary structure of a protein?
The interactions of the different RR-groups with other RR-groups and with their environment determine the tertiary structure of the protein.
Lysosomes digest food particles brought into a cell by endocytosis. After a vesicle containing food particles fuses with a lysosome, H+ ions are transported into the lysosome from the cytosol. This significantly lowers the pH of the lysosome relative to the cytosol and activates the enzymes that digest the particles. Which of the following best predicts what will happen to the lysosomal enzymes if the proteins that transport H+ ions from the cytosol into the lysosome are damaged?
The lysosomal enzymes will not become active, since there will be no active transport of H+ ions.
Gaucher disease is an inherited disorder in which cells of the body are unable to break down a particular type of lipid, resulting in a buildup of the lipid in some tissues and organs. Based on the information provided, Gaucher disease results most directly from a defect in the function of which of the following organelles?
The lysosome
Water and ammonia interact to form hydrogen bonds, as represented in the figure.Which statement best helps explain the formation of the hydrogen bond represented in the figure?
The nitrogen has a partial negative charge, and the hydrogen attached to the oxygen has a partial positive charge.
A certain type of specialized cell contains an unusually large amount of rough endoplasmic reticulum (ER). Which of the following functions is this cell type most likely specialized to perform?
The production and secretion of proteins
Stomata are pores on the surfaces of the leaves and stems of plants that regulate gas exchange between the plants and the atmosphere. Researchers found that the stomata density on the leaves of a species of plant change as the concentration of CO2 in the atmosphere changes. When grown at 350 ppm CO2 the plant has an average density of 300 stomata per mm2, but when grown at 400 ppm CO2 the plant has an average density of 250 stomata per mm2. Which of the following best describes how the ratio of the density of stomata (stomata per mm2 per CO2CO2 concentration (ppm CO2 changes as the CO2 concentration increases?
The ratio decreases from 0.86 to 0.63 because fewer stomata are needed at higher CO2 concentrations.
Hereditary spherocytosis (HS) is a disorder of red blood cells that causes the cells to be smaller and spherical instead of having the usual flattened, biconcave shape. The average diameter of normal red blood cells is 7.2μm and the average diameter of red blood cells in a person with HS was found to be 6.7μm The normal red blood cell has an average surface area of 136μm21and an average volume of 91μm39. Which of the following provides an accurate calculation of the surface area to volume ratio of an HS red blood cell, as well as a prediction of its effect on the efficient transferring of oxygen compared to a normal red blood cell?
The ratio is 0.89 and the cells are less efficient at transferring oxygen.
A scientist is studying the various prokaryotic and eukaryotic species found floating in a sample of water taken from a marine ecosystem. Which cellular component will be found in the widest range of organisms in the sample?
The ribosome, since all organisms need to synthesize proteins.
Which of the following statements best helps explain the reaction specificity of an enzyme?
The shape and charge of the substrates are compatible with the active site of the enzyme.
Which of the following transport mechanisms will be affected most directly by a temporary shortage of ATP molecules inside the cell?
The transport of glucose molecules against a concentration gradient
Researchers conducted an experiment to investigate the effects of a valinomycin treatment on skeletal muscle cells. Valinomycin is a naturally occurring substance that can be used as a drug. The results of the experiment are presented in the table. Which of the following claims about the effects of the valinomycin treatment is best supported by the data presented in the table?
The valinomycin treatment caused a decrease in the activity of the mitochondria.
Which of the following best describes the structures of carbohydrates?
They occur as monomers, chains of monomers, and branched structures.
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 pHpH 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.
Certain bacteria can use both ethyl alcohol and acetate as sources of nutrients. In an experiment where both nutrients are available to a bacterial population, the following results were obtained and graphed. What additional procedure would best help determine whether these movements are due to active transport or to passive transport?
Use two additional treatments, one containing only ethyl alcohol and one containing only acetate. Include a substance known to block ATP use by the plasma membrane. Compare the graphs of these two treatments to the original graph.
Beetroot cells contain a family of dark red pigments called betalains. The selectively permeable nature of the beetroot cells keeps the internal environment of the cell separate from the external environment of the cell. Researchers are interested in determining whether the selective permeability of beetroot cells is due to the cell membrane or if it is due to the cell wall. Exposure to cellulase is known to damage the structure of the cell wall. An experiment is set up in which beetroot cells are placed in an aqueous solution with cellulase and in one without cellulase. Which of the following results best refutes the alternative hypothesis that selective permeability is a consequence of the cell wall?
When beetroot cells are placed in a solution with cellulase, the solution remains clear.
Figure 1 shows a model of how a channel protein influences the movement of a particle across a cell's plasma membrane.Figure 1. A section of a cell's plasma membrane, showing a channel protein and a concentration gradient across the membrane An investigator wants to understand whether a newly found membrane protein is involved in membrane transport of a certain particle. Which investigation will help determine whether the new membrane protein is a channel protein involved in membrane transport?
dd more of the proteins to the plasma membrane and measure the rate of the particle movement.
A model of the plasma membrane showing several biological molecules, including a transmembrane protein, is shown in Figure 1.Which statement best explains why correct protein folding is critical in the transmembrane protein shown above?
nteractions of the hydrophobic and hydrophilic amino acids help to anchor the protein in the membrane.
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
ower than the level at ph 9
Testosterone is a small steroid hormone that is important in cell signaling. Which of the following describes where testosterone enters a cell and why it is able to cross at that point?
testosterone is nonpolar and can diffuse through the membrane.
