AP Bio test 2
Simple cuboidal epithelial cells line the ducts of certain human exocrine glands. Various materials are transported into or out of the cells by diffusion. (The formula for the surface area of a cube is 6 X S2, and the formula for the volume of a cube is S3, where S = the length of a side of the cube.) Which of the following cube-shaped cells would be most efficient in removing waste by diffusion?
10 micrometers
To model a plant cell, a permeable, nonflexible case is placed around each piece of dialysis tubing. The greatest pressure potential will develop within dialysis tube number
4
The contents of which dialysis tube are initially isotonic to the distilled water in the beaker?
5
A net movement of water into beaker in which beaker? Dialysis tubing is permeable to water molecules but not to sucrose. Four dialysis tubes are half filled with 5 percent, 10 percent, 20 percent, and 40 percent sucrose solutions, respectively, and two dialysis tubes are half filled with distilled water. The dialysis tubes are all sealed at both ends, and the initial masses are determined. Five dialysis tubes are placed into beakers containing distilled water, and the sixth dialysis tube, containing distilled water, is placed into a 40 percent sucrose solution. The masses of the dialysis tubes are recorded at 30-minute intervals for 90 minutes, as shown in the table below.
6
Based on the model, what will be the mean diameter of the phytoplankton cells that are found 25 kilometers from shore?
650 micrometers
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.
What is the most likely identity of protein X ?
An enzyme that participates in the degradation and recycling of cell components
In vascular plants, water flows from root to leaf via specialized cells called xylem. Xylem cells are hollow cells stacked together like a straw. A student explains that evaporation of water from the leaf pulls water up from the roots through the xylem, as shown in Figure 1. The figure presents a diagram of water flow through a plant. Arrows labeled Xylem Tissues Carry Water point from the roots into and up through the stem of the plant. Some of the arrows also point into a leaf. The leaf is shaded and labeled Water from the Soil. Arrows point out from the leaf into the air and are labeled Evaporation of Water from Leaves. A zoomed in portion of the stem shows the xylem in the stem, with dots representing water molecules and arrows pointing up through the xylem. A zoomed in portion of the leaf shows a cross section of the leaf with leaf cells on each side of a row of xylem-like cells that contain the dots that represent water. More dots are shown moving from the leaf into the air through an opening between the leaf cells. Figure 1. Model of water movement through the xylem, with magnified models of water movement in the stem and leaf. Which statement describes how water is pulled up through the xylem to the leaves of the plant?
As water exits the leaf, hydrogen bonding between water molecules pulls more water up from below.
Which of the following best describes a structural similarity between the two molecules shown in Figure 1 that is relevant to their function? The figure presents two molecules. Molecule 1 represents R N A, which is a single stranded helix. Nitrogenous bases are attached to a backbone. Molecule 2 represents D N A, which is a double stranded helix. Nitrogenous bases join the two strands together. Figure 1. Molecule 1 represents RNA, and molecule 2 represents DNA.
Both molecules contain nucleotides that form base pairs with other nucleotides, which allows each molecule to act as a template in the synthesis of other nucleic acid molecules.
Which of the following would most likely occur if cattle lost the ability to maintain a colony of microorganisms in their digestive tract?
Cattle would no longer be able to use cellulose as a primary source of glucose.
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. Cell 1 2 3 4 Total surface area (μm2) 40 60 80 100 Total volume (μm3) 20 10 30 20 Based on the data, which cell is likely to be most effective in the exchange of materials?
Cell 2
Which of the following descriptions of cell type I and cell type II are most consistent with the data? Sticklebacks
Cell Type I Cell Type II Animal cell surrounded by a plasma membrane only Plant cell surrounded by a plasma membrane and a cell wall
A student wants to modify model 1 so that it represents an RNA double helix instead of a DNA double helix. Of the following possible changes, which would be most effective in making model 1 look more like RNA than DNA?
Changing the deoxyriboses to riboses by adding −OH groups
site of glucose synthesis
Chloroplast
Which two cellular organelles in eukaryotes have both electron transport systems and chemiosmotic mechanisms?
Chloroplasts and mitochondria
Which of the following correctly shows the order in which protein X moves through the cell?
Endoplasmic reticulum → Golgi apparatus → lysosomes
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. The figure presents a Euglenid. A chloroplast is labeled inside the euglenid. There is also an enlarged zoomed-in figure of a portion of the chloroplast. The three membranes of the envelope that surrounds the chloroplast are labeled Chloroplast Envelope, and the innermost membrane of the three is labeled Inner Membrane. The zoom-in also shows a portion of a thylakoid inside the chloroplast itself, and a label points to 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.
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. RELATIVE AMOUNTS OF RADIOLABELED AMINO ACID Nucleus Mitochondria Endoplasmic Reticulum Cytosol 2.1 2.7 1.9 1 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.
If, instead of the bag, a potato slice were placed in the beaker of distilled water, which of the following would be true of the potato slice?
It would gain mass.
Which of the following processes is most likely to occur as a result of an animal cell receiving a signal to initiate apoptosis?
Lysosomes will release digestive enzymes into the cytosol.
The figure shows a representation of a protein embedded in a cell membrane. The numbers indicate different structural regions of the protein. The figure presents a cell membrane lipid bilayer. A protein is embedded in one half of the bilayer. The exposed surface of the protein that protrudes from the membrane is labeled 1, and the part of the protein that associates with the fatty acid tails in the interior of the membrane is labeled 2. 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 figure presents three blood cells. The left cell is swollen, the middle cell is of normal disc shape, and the right cell is shrunken and irregular. 0.3% Saline (Cells swell) 0.9% Saline (Cells unchanged) 1.5% Saline (Cells shrink) 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.
The salinity of a small inland lake has recently started to increase. Researchers are planning to study the lake over several decades to investigate how freshwater organisms survive significant changes in their natural habitat. Which of the following physiological mechanisms will the researchers most likely observe among the surviving organisms in the lake?
Single-celled organisms will use various mechanisms to counteract the increased flow of water from cells to the environment.
Based on Figure 1, which of the following best compares the atomic structures of starch and cellulose? Different polysaccharides are used by plants for energy storage and structural support. The molecular structures for two common polysaccharides are shown in Figure 1. Starch is used by plants for energy storage, and cellulose provides structural support for cell walls. The monomer used to construct both molecules is glucose.
Starch and cellulose are composed of repeating glucose monomers; however, in cellulose every other glucose monomer is rotated 180 degrees.
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.
The Na+ concentration inside the cell will increase.
Figure 1 shows three amino acids that are part of a polypeptide chain. Figure 2 shows the same section of the chain after a mutation has occurred. Two figures are presented. Figure 1 presents the Original Amino Acid Chain, with an aspartic acid on the left, followed by a cysteine, followed by a lysine. Aspartic acid has a negative 1 charge on its R group, cysteine has an uncharged R group composed of a carbon atom bonded to two hydrogen atoms and an S H group, and lysine has a positive 1 charge on its R group. Figure 2 presents the Mutated Amino Acid Chain, with an aspartic acid on the left, followed by a valine, followed by a lysine. Aspartic acid has a negative 1 charge on its R group, valine has an uncharged R group composed of a carbon atom bonded to one hydrogen atom and two C H 3 groups, and lysine has a positive 1 charge on its R group. How might this change affect the structure and function of the protein?
The R-group of the new amino acid, valine, has different chemical properties than the R-group of cysteine. This will cause the protein to misfold and not function properly in the cell.
A polypeptide is polymer of amino acids held together by peptide bonds. The process of dehydration synthesis creates these peptide bonds, as shown in Figure 1. The figure presents the chemical reaction that links two amino acids. The two amino acids are identical except for their R groups. The central atom in each amino acid is a carbon atom. The left side of each amino acid is an N H 2 group in which a nitrogen atom is bonded to two hydrogen atoms, and the right side of each amino acid is a C O O H group in which a carbon atom is double bonded to an oxygen atom and single bonded to the oxygen atom of an O H group. The R group of the first amino acid is labelled R prime, and the R group of the second amino acid is labelled R double prime. The two amino acids are joined by a peptide bond, and a molecule of water is produced. The peptide bond consists of a bond between a carbon and a nitrogen atom. The carbon atom in the peptide bond is also bonded to the carbon atom that bears the R prime group and double bonded to an oxygen atom. The nitrogen atom in the peptide bond is also bonded to the carbon atom that bears the R double prime group and to a hydrogen atom. Figure 1. Amino acids are linked through the formation of peptide bonds. As shown in Figure 1, an amino acid must have which of the following properties in order to be incorporated into a polypeptide?
The ability to form a covalent bond with both its NH2 group and its COOH group
Which of the following best describes the condition expected after 24 hours?
The bag will contain more water than it did in the original condition
Paramecia are unicellular protists that have contractile vacuoles to remove excess intracellular water. In an experimental investigation, paramecia were placed in salt solutions of increasing osmolarity. The rate at which the contractile vacuole contracted to pump out excess water was determined and plotted against osmolarity of the solutions, as shown in the graph. Which of the following is the correct explanation for the data?
The contraction rate increases as the osmolarity decreases because the amount of water entering the paramecia by osmosis increases.
Based the information provided, which of the following statements best describes why starch and cellulose provide different functions in plants?
The differences in the assembly and organization of the monomers of these two polymers result in different chemical properties.
A student is using dialysis bags to model the effects of changing solute concentrations on cells. The student places one dialysis bag that contains 25 mL of distilled water into each of two beakers that are filled with 200 mL of distilled water. (Figure 1). The membrane of each dialysis bag membrane contains pores that allow small solutes such as monoatomic ions to pass through but are too small for anything larger to pass. After 30 minutes, 5 mL of a concentrated solution of albumin (a medium-sized, water-soluble protein) is added to one of the two beakers. Nothing is added to the other beaker. After two more hours at room temperature, the mass of each bag is determined. There is no change in the mass of the dialysis bag in the beaker to which no albumin was added. Which of the graphs below best represents the predicted change in mass over time of the dialysis bag in the beaker to which albumin was added?
The figure presents a graph in the coordinate plane. The horizontal axis is labeled Time, in minutes, and the numbers 0 through 150, in increments of 30, are indicated. The vertical axis is labeled Relative Mass of Dialysis Bag. The axis has an arrowhead at the top end, and no numbers are indicated along it. The graphed line begins at 0 minutes, about halfway up the vertical axis, and extends horizontally to the right until 30 minutes. A label indicates Albumin Added at 30 minutes. The graphed line starts to move downward and to the right at 30 minutes until it ends at 150 minutes, just above the horizontal axis.
Cholesterol is a naturally occurring substance that helps regulate the fluidity of a cell's plasma membrane. A cholesterol molecule can be represented as having a polar head and a nonpolar region, as shown in the figure. The figure presents a cholesterol molecule. A black dot indicates the polar head, which is attached to a nonpolar region that is represented by a sequence of four hexagons or a pentagon, each of which shares one side with the previous and/or next component of the region. Which of the following models shows how cholesterol molecules most likely interact with the phospholipid bilayer of a cell's plasma membrane?
The figure presents a phospholipid bilayer and cholesterol molecules. The polar head of each cholesterol molecule is situated between the heads of the phospholipids, and the nonpolar region extends into the interior of the membrane between the phospholipid tails.
Researchers have proposed a model of the process by which a newly synthesized protein is transported to the plasma membrane and secreted into the extracellular space. The model is represented in Figure 1. Figure 1 presents a diagram of a cell. The following parts are labeled: nucleus, endoplasmic reticulum, ribosomes, cytosol, and new protein in transport vesicle. The transport vesicle containing a new protein is shown in two positions: a start point and an end point. It starts out adjacent to the endoplasmic reticulum, and an arrow is drawn upward from the transport vesicle toward an unlabeled component. The unlabeled component appears to be a series of stacked flat sacs. A second arrow is drawn upward from this unlabeled component toward the plasma membrane, where the transport vesicle with new protein is shown at its end point just inside the plasma membrane. Figure 1. A model of the intracellular transport of a newly synthesized secreted protein Based on the model, the newly synthesized protein is transported directly from the endoplasmic reticulum to which of the following?
The golgi complex
Which of the following statements is most consistent with the data in the table?
The kidneys of reptiles and birds are highly efficient because little water is needed to excrete uric acid.
Which feature of model 1 best illustrates how biological information is coded in a DNA molecule?
The linear sequence of the base pairs
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
Phosphorous (P) is an important nutrient for plant growth. Figure 1 shows Arabidopsis thaliana plants grown under phosphorus‐sufficient (left) and phosphorus‐starved (right) conditions for six weeks. The figure presents two potted plants. The plant on the left is labeled Phosphorus Sufficient, and is large. The plant on the right is labeled Phosphorus Starved, and is small. Figure 1. Arabidopsis thaliana plants grown for six weeks. Which of the following is the most likely reason for the difference in leaf growth?
The phosphorus-starved plant was unable to synthesize both the required nucleic acids and lipids, limiting growth.
From the initial conditions and results described, which of the following is a logical conclusion?
The pores of the bag are larger than the glucose molecules but smaller than the starch molecules.
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 136μm2 and an average volume of 91μm3. 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.
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. Relative Rates of ATP Production Time after Treatment Untreated Cells Valinomycin-Treated Cells 5 minutes 1.0 0.3 10 minutes 7.7 2.7 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.
The figure presents a lake covered by a layer of ice. The air above the ice is negative 5 degrees Celsius. Immediately below the ice, the temperature of the lake water is 0 degrees Celsius. The water deeper in the lake is 4 degrees Celsius. There is a fish in this deeper water. As shown in the diagram, when environmental temperatures drop below freezing, a layer of ice typically forms on the surface of bodies of freshwater such as lakes and rivers. Which of the following best describes how the structure of ice benefits the organisms that live in the water below?
The water molecules in ice are farther apart than those in liquid water, so the ice floats, maintaining the warmer, denser water at the lake bottom.
Which of the following best predicts which diagrammed microscope view the laboratory worker would see and best explains why?
They have highly folded membranes.
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. The figure presents two curves in the first quadrant of a coordinate plane, titled "Movement of Nutrients into Bacterial Cells." The horizontal axis is labeled Concentration Outside Cells, in milimolarity, and the numbers 0.1, 1.0, 10.0, and 100.0 are indicated at equal intervals. The vertical axis is labeled Rate of Entry of Substance, in micromoles per minute, and the numbers 10, 100, and 1,000 are indicated at equal intervals. The first curve, labeled Acetate, is a straight line that begins at the point 0.1 milimolar, 1.5 micromoles per minute, and moves upward and to the right, passing through the point 1.0 milimolar, 10.4 micromoles per minute. The curve then passes through the point 10.0 milimolars, 107 micromoles per minute, and ends at the point 100.0 milimolars, 1,020 micromoles per minute. The second curve, labeled Ethyl Alcohol, begins at the point 0.1 millimolar, 7 micromoles per minute, and moves gradually upward and to the right, passing through the point 1.0 millimolar, 20 micromoles per minute. It then passes through the point 10.0 millimolar, 35 micromoles per minute, and ends at the point 100.0 milimolar, 50 micromoles per minute. 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.
The last part of the metamorphosis of a tadpole to an adult frog results in the disappearance of the tail. This stage of development most likely occurs by
cells of the tail dying and the nutrients being absorbed and reused by the body
The figure above shows a series of microscope images taken over time of ovalbumin production in chick oviduct cells in response to stimulation with estrogen. The ovalbumin protein was detected using a fluorescent dye as shown by the white areas in the time-lapse sequence. The microscope images indicate that ovalbumin
crosses the endoplasmic reticulum membrane as it is translated, then moves to the Golgi apparatus, then to vesicles from which it is secreted
In an experiment, the efficiency of oxygen exchange across the plasma membrane is being assessed in four artificial red blood cells. The table above lists some properties of those artificial cells. Other conditions being equal, which artificial cell is predicted to be the most efficient in exchanging oxygen with the environment by diffusion?
cuboidal cell
The same procedure was repeated with a second protein (protein Y). If the function of Y is protein processing and packaging, the most radioactivity would be found in the
golgi apparatus
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
Site of conversion of chemical energy of glucose to ATP
mitochondria
In graphing the data from this experiment, the sampling time would be shown on the x-axis because
sampling time is the independent variable
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?
simple diffusion
Site of modification and packaging of proteins and lipids prior to export from the cell
smooth ER
