Bio AP Classroom Questions
The approximate molarity of the solution in which the mass of the plant pieces would not change is 0.0 M 0.1 M 0.3 M 0.5 M 0.7 M
0.3M
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 2 3 4 5 6
4 (mass increased the most)
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. The contents of which dialysis tube are initially isotonic to the distilled water in the beaker? 1 2 3 4 5
5 (Mass remained constant)
Based on Table 1, which of the following percentages is closest to the solute concentration of the grape? 0.0% 1.3% 5.5% 10.1%
5.5%
A net movement of water into the beaker occurs in which of the following dialysis tubes? 2 3 4 5 6
6 (mass decreased most b/c water entered the dialysis tubing)
The student prepared identical samples of beet root tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beet root cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above. Question Which of the following graphs is the most appropriate representation of the experimental data?
A (bar graph with error bars)
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? Add small nonpolar molecules to the extracellular space and measure the direction of particle movement of the molecules. Measure the rate of extracellular fluid movement into the intracellular space. Add more of the proteins to the plasma membrane and measure the rate of the particle movement. Remove ATP from the intracellular space and measure the rate of the particle movement into the intracellular space.
Add more of the proteins to the plasma membrane and measure the rate of the particle movement.
Which of the following best describes the numbered areas? Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules. Area 2 is polar, since water has been excluded from this area of the membrane. Areas 1 and 3 are hydrophilic, since membrane molecules formed covalent bonds with water. Area 2 is nonpolar, since hydrogen bonds between the adjacent lipids hold the membrane together.
Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules.
The illustration above is a model of a typical beet root cell. Based on the experimental results, which of the following best represents the effect of acetone on the permeability of cellular membranes?
B (one with dashed lines in the after)
A pathogenic bacterium has been engulfed by a phagocytic cell as part of the nonspecific (innate) immune response. Which of the following illustrations best represents the response?
C has black circles (lysosomes) in it
Intact cells of two unknown cell types were placed into solutions with different concentrations of NaCl. Type I cells swelled and burst in the solution with the lowest concentration of NaCl. Type II cells swelled but did not burst in the solution with the lowest concentration of NaCl. Which of the following descriptions of cell type I and cell type II are most consistent with the data?
Cell type 1- animal cell surrounded by a plasma membrane only Cell type 2- plant cell surrounded by a plasma membrane and a cell wall
Which of the following data would support the alternative hypothesis? Cells with functional aquaporins exhibit low turgor pressure and are hypertonic. Cells with functional aquaporins exhibit high turgor pressure and are hypotonic. Cells with mutated aquaporins exhibit an absence of turgor pressure and are completely plasmolyzed. Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.
Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.
Which of the following describes the most likely location of cholesterol in an animal cell? Embedded in the plasma membrane Dissolved in the cytosol Suspended in the stroma of the chloroplast Bound to free ribosomes
Embedded in the plasma membrane
Carbon dioxide most likely enters a cell through which of the following processes? Simple diffusion through the membrane Facilitated diffusion through membrane proteins Active transport through membrane proteins Active transport through aquaporins
Facilitated diffusion through membrane proteins
Which of the following best predicts the effect of not having ATP available to supply energy to this process? H+ ions will stop moving through the protein. H+ ions will move in the other direction through the protein. H+ ions will continue to move through the protein in the original direction but at a slower rate. H+ ions will begin to move through the phospholipid portion of the membrane in the original direction.
H+ ions will stop moving through the protein.
Of the following, which additional investigation can be used to determine when the cells are in an isotonic solution? Decreasing the salinity of the environment a little at a time until the ATP usage reaches a maximum Decreasing the salinity of the environment a little at a time until ATP usage reaches a minimum Increasing the salinity of the environment a little at a time until ATP usage reaches a maximum Increasing the salinity of the environment a little at a time until the ATP usage reaches a minimum
Increasing the salinity of the environment a little at a time until the ATPATP usage reaches a minimum
The active transport pump used to move sodium ions across the membranes of gill cells in a freshwater fish has each of the following characteristics EXCEPT: It uses osmosis to carry sodium ions into the cells. It requires energy. It has a specific binding site for ATP. It has a specific binding site for sodium ions. It is a protein.
It uses osmosis to carry sodium ions into the cells.
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. It would neither gain nor lose mass. It would absorb solutes from the surrounding liquid. It would lose water until water potential inside the cells is equal to zero. The cells of the potato would increase their metabolic activity.
It will gain mass
Which of the following accurately describes one of the movements taking place? Glucose is transported into the cell by active transport. Na+ is transported into the cell by active transport. The movement of glucose through the membrane requires ATP hydrolysis. Na+ transport out of the cell requires ATP hydrolysis.
Na+ transport out of the cell requires ATP hydrolysis.
Based on Table 1, which of the following best explains the difference in water potential between certain solutions and the grapes? NaCl and tap water have a lower water potential because these two solutions caused the grape to gain water. Grape soda and NaCl have a lower water potential because these two solutions caused the grape to lose water. Tap water and grape juice have a lower water potential because these two solutions caused the grape to lose water. Grape soda and grape juice have a lower water potential because these two solutions caused the grape to gain water.
NaCl and tap water have a lower water potential because these two solutions caused the grape to gain water.
If ATP breakdown (hydrolysis) is inhibited, which of the following types of movement across cell membranes is also inhibited? Movement of oxygen into a cell Movement of water through aquaporins Passage of a solute against its concentration gradient Facilitated diffusion of a permeable substance
Passage of a solute against its concentration gradient
Which of the following statements best explains the processes of passive and active transport? Passive transport is the net movement of substances down a concentration gradient that requires metabolic energy. Active transport is the movement of substances up a concentration gradient that does not require energy. Passive transport is the net movement of substances down a concentration gradient that does not require metabolic energy. Active transport is the movement of substances up a concentration gradient that requires energy. Passive transport is the net movement of substances up a concentration gradient that requires metabolic energy. Active transport is the movement of substances down a concentration gradient that does not require metabolic energy. Passive transport is the net movement of substances up a concentration gradient that does not require metabolic energy. Active transport is the movement of substances down a concentration gradient that requires energy.
Passive transport is the net movement of substances down a concentration gradient that does not require metabolic energy. Active transport is the movement of substances up a concentration gradient that requires energy.
A student placed a semipermeable membrane inside a U-shaped channel with two chambers, as shown. The membrane permits the movement of water but not salt. The student wants to vary the rate of osmosis that occurs across the membrane. Which of the following experimental designs will result in the fastest net rate of water movement into chamber A? Placing salt water in chamber A and distilled water in chamber B Placing distilled water in both chambers Placing distilled water in chamber A and salt water in chamber B Placing salt water in both chambers
Placing salt water in chamber A and distilled water in chamber B
Which of the following components of the cell membrane is responsible for active transport? Phospholipid Protein Lipid Phosphate Cholesterol
Proteins
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? Prokaryotic organisms will use various mechanisms to counteract swelling of cells as a result of increased water uptake. Single-celled organisms will use various mechanisms to counteract the increased flow of water from cells to the environment. Eukaryotic organisms will use various mechanisms to counteract the diffusion of positively charged ions across the cell membrane. Multicellular organisms will use various mechanisms to counteract the loss of cell adhesion as a result of calcium deficiencies.
Single-celled organisms will use various mechanisms to counteract the increased flow of water from cells to the environment.
Assuming a negligible pressure potential, which of the following best predicts the net movement of the small diffusible solutes and water in the second experiment (Table 2) ? Small diffusible solutes will diffuse into the grape cells, followed by water. Small diffusible solutes will diffuse out of the grape cells and water will diffuse into the cells. Small diffusible solutes will diffuse out of the grape cells, followed by water. Small diffusible solutes will diffuse into the grape cells and water will diffuse out of the cells.
Small diffusible solutes will diffuse into the grape cells, followed by water.
Which of the following is the dependent variable in the experiment? The percent by volume of isopropanol in the treatment solutions The percent by volume of water in the treatment solutions The length of time each sample was incubated in the treatment solutions The absorbance of 460 nm light by the treatment solutions
The absorbance of 460 nm light by the treatment solutions
Based on the information presented, which of the following is the most likely explanation for a buildup of cholesterol molecules in the blood of an animal? The animal's body cells are defective in exocytosis. The animal's body cells are defective in endocytosis. The animal's body cells are defective in cholesterol synthesis. The animal's body cells are defective in phospholipid synthesis.
The animal's body cells are defective in endocytosis.
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. The contents of the bag will have the same osmotic concentration as the surrounding solution. Water potential in the bag will be greater than water potential in the surrounding solution. Starch molecules will continue to pass through the bag. A glucose test on the solution in the bag will be negative.
The bag will contain more water than it did in the original condition.
Intravenous (IV) solutions administered to patients are normally isotonic. Which of the following is most likely if an IV of distilled water is administered to a patient? The cells that are exposed to hypotonic solutions will shrink as a result of salt moving into the blood. The liver will secrete additional bile salts into the blood to raise the tonicity of the administered fluid. The cells that are exposed to hypotonic solutions will expand as water moves osmotically into the cells from the blood. The patient's respiration rate will slow to compensate for the higher levels of circulating blood.
The cells that are exposed to hypotonic solutions will expand as water moves automatically into the cells from the blood.
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? At higher osmolarity, lower rates of contraction are required because more salt diffuses into the paramecia. The contraction rate increases as the osmolarity decreases because the amount of water entering the paramecia by osmosis increases. The contractile vacuole is less efficient in solutions of high osmolarity because of the reduced amount of ATP produced from cellular respiration. In an isosmotic salt solution, there is no diffusion of water into or out of the paramecia, so the contraction rate is zero.
The contraction rate increases as the osmolarity decreases because the amount of water entering the paramecia by osmosis increases.
Which of the following, if true about the drug, best supports the alternative hypothesis that the new drug will exhibit simple diffusion across plasma membranes? The drug is a small nonpolar molecule. The drug is a small charged molecule. The drug is a large polar molecule. The drug is a large charged molecule.
The drug is a small nonpolar molecule.
Mercurial sulfhydryl is an inhibitor of aquaporins. Which of the following is the most likely effect of adding mercurial sulfhydryl to the distilled water solution? The grape cells will burst because of excess water entering by active transport. The grape cells will gain more water because of the activation of the transport protein. The grape cells will shrink because active transport has been inhibited. The grape cells will gain water more slowly because of a lack of facilitated diffusion.
The grape cells will gain water more slowly because of a lack of facilitated diffusion.
Which statement best explains the orientation of the phospholipid molecules in this model? The nonpolar portions of the phospholipid molecules are attracted to the internal and external environments. The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments. The embedded proteins attract the fatty acid tails of the phospholipids, so the tails point away from the internal and external aqueous environments. The fatty acid tails of the phospholipid molecules are hydrophilic and are repelled by the internal and external aqueous environments.
The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments.
Based on the data in Table 1, which of the following best evaluates the student's hypothesis? The hypothesis is supported because the mass of the grape decreased in the grape juice. The hypothesis is supported because the grape juice has a greater solute potential than the grape has. The hypothesis is not supported because the grape was isotonic to the grape juice. The hypothesis is not supported because the mass of the grape increased in the grape juice.
The hypothesis is not supported because the mass of the grape increased in the grape juice.
Which of the following best explains how molecules such as O2O2 and CO2CO2 can move across the membrane of a cell? The majority of the cell membrane contains protein channels that allow this type of molecule into the cell. The majority of the cell membrane is nonpolar, which allows small, nonpolar molecules to freely cross. The phospholipids of the membrane are tightly packed, so only small molecules and ions can fit between phospholipids. ATP is hydrolyzed to provide energy to help O2 and CO2 move against their concentration gradient and across the membrane.
The majority of the cell membrane is nonpolar, which allows small, nonpolar molecules to freely cross.
A student used a microscope to observe a wet-mount slide of red onion epidermal cells that were suspended in a 1% NaCl solution. The student then added a 15% NaCl solution to the slide and observed the changes that occurred. The student's observations are represented in Figure 1. Figure 1. Student's observations of onion cells Which of the following most directly explains the changes in the cells? The degradation of DNA in the nuclei of the cells The lysis of chloroplasts in the cells The movement of water from the central vacuoles of the cells into the solution The movement of NaCl from the solution into the cytoplasm of the cells
The movement of water from the central vacuoles of the cells into the solution
If ADH secretion is inhibited, which of the following would initially result? The number of aquaporins would increase in response to the inhibition of ADH. The person would decrease oral water intake to compensate for the inhibition of ADH. Blood filtration would increase to compensate for the lack of aquaporins. The person would produce greater amounts of dilute urine.
The number of aquaporins would increase in response to the inhibition of ADH.
Which of the following best explains how the phospholipid bilayer of a transport vesicle contributes to cellular functions? The phospholipid bilayer allows the vesicle to fuse with the Golgi apparatus and the plasma membrane, allowing the exocytosis of proteins. The phospholipid bilayer physically connects the nuclear envelope to the rough endoplasmic reticulum, thus increasing the rate of transcription and translation. The phospholipid bilayer of a transport vesicle contains chemicals that digest the proteins made in the rough endoplasmic reticulum. The phospholipid bilayer contains enzymes that catalyze the conversion of hydrogen peroxide to water and oxygen.
The phospholipid bilayer allows the vesicle to fuse with the Golgi apparatus and the plasma membrane, allowing the exocytosis of proteins.
The following questions refer to an experiment in which a dialysis-tubing bag is filled with a mixture of 3% starch and 3% glucose and placed in a beaker of distilled water, as shown below. After 3 hours, glucose can be detected in the water outside the dialysis-tubing bag, but starch cannot. From the initial conditions and results described, which of the following is a logical conclusion? The initial concentration of glucose in the bag is higher than the initial concentration of starch in the bag. The pores of the bag are larger than the glucose molecules but smaller than the starch molecules. The bag is not selectively permeable. A net movement of water into the beaker has occurred. The molarity of the solution in the bag and the molarity of the solution in the surrounding beaker are the same.
The pores of the bag are larger than the glucose molecules but smaller than the starch molecules.
Which of the following statements best explains the observations represented in Figure 1 ? There was a net movement of sucrose out of the cell suspended in the sugar solution and a net movement of sucrose into the cell suspended in the distilled water. There was a net movement of sucrose into the cell suspended in the sugar solution and a net movement of sucrose out of the cell suspended in the distilled water. There was a net movement of water out of the cell suspended in the sugar solution and a net movement of water into the cell suspended in the distilled water. There was a net movement of water into the cell suspended in the sugar solution and a net movement of water out of the cell suspended in the distilled water.
There was a net movement of water out of the cell suspended in the sugar solution and a net movement of water into the cell suspended in the distilled water.
The student analyzed the data from the investigation and concluded that the estimate of the mean of one treatment group was unreliable. Which of the following identifies the treatment group most likely to have provided an unreliable estimate of the mean, and correctly explains why the estimate appears unreliable? Treatment group II; it has a lower than expected mean absorbance and the largest standard error of the mean. Treatment group III; it has a higher than expected mean absorbance and the largest standard error of the mean. Treatment group III; it has a higher than expected mean absorbance and the largest standard error of the mean. Treatment group IV; it has a higher than expected mean absorbance and the smallest standard error of the mean. Treatment group V; it has a lower than expected mean absorbance and the smallest standard error of the mean.
Treatment group II; it has a lower than expected mean absorbance and the largest standard error of the mean.
A scientist designed an experiment to test an artificial membrane that mimics the phospholipid bilayer of a cell. The scientist built a tube that was divided by an artificial membrane and filled with distilled water. The scientist put a known amount of a protein into the water on one side of the membrane. After some time, the scientist measured the concentration of the protein on either side of the membrane but found that there had been no change. Which of the following experimental changes would allow the scientist to observe transport of a solute across the artificial membrane? Increase the solute concentration in the solution Use a small, nonpolar solute instead of a protein Increase the temperature of the solution Add artificial aquaporins to the membrane
Use a small, nonpolar solute instead of a protein
Which of the following best predicts which diagrammed microscope view the laboratory worker would see and best explains why? View 1 because RBC membranes are freely permeable to water View 2 because the RBCs use energy to allow sodium entry and to pump water out View 2 because the rate of water movement into the RBCs equals the rate of water movement out of the cells View 3 because the sodium-potassium pumps in the RBC membranes use energy to keep the sodium out but allow water to freely flow into the cells
View 2 because the rate of water movement into the RBCs equals the rate of water movement out of the cells
Which statement best describes the effect on water transport across the cell membrane if the aquaporin in the figure ceases to function? Water molecules will no longer be able to move across the cell membrane. Water molecules will no longer be able to move across the cell membrane. Water molecules will still be able to move across the cell membrane but at a slower rate. Water molecules will only be able to enter the cell by active transport. Water molecules will move across the cell membrane at a faster rate without the aquaporin regulating their flow.
Water molecules will still be able to move across the cell membrane but at a slower rate.
Which of the following scientific questions is most relevant to the model represented in the figure above? Is ATP required for the transportation of sugars across the outer mitochondrial membrane? Do the types of phospholipids in a membrane affect the rate at which molecules enter a cell by passive diffusion? Which molecular substance is actively transported across the plasma membrane? How does temperature affect the movement of molecules into lysosomes?
Which molecular substance is actively transported across the plasma membrane?
Based on the data from the investigation, which of the following is the best scientific question about organisms living in water that is polluted with organic solvents? Do organisms without pigments have a selective advantage in polluted environments? Will organisms living in polluted environments exhibit detrimental effects from an increased permeability of their cellular membranes? Will organic solvents from the environment become incorporated into the cell membranes of organisms living in polluted environments? Should governments place more stringent restrictions on the release of organic solvents into aquatic ecosystems?
Will organisms living in polluted environments exhibit detrimental effects from an increased permeability of their cellular membranes?
Simple diffusion and facilitated diffusion are related in that both require protein carriers depend on a concentration gradient occur via contractions of cytoskeletal elements attached to membrane proteins are endergonic processes and thus require the hydrolysis of ATP occur in eukaryotic cells but not in prokaryotic cells
depend on a concentration gradient
Water enters and leaves the plant cells primarily by endocytosis phagocytosis osmosis active transport facilitated diffusion
osmosis
A common laboratory investigation involves putting a solution of starch and glucose into a dialysis bag and suspending the bag in a beaker of water, as shown in the figure below. The investigation is aimed at understanding how molecular size affects movement through a membrane. Which of the following best represents the amount of starch, water, and glucose in the dialysis bag over the course of the investigation?
y-axis: relative amount in dialysis bag x-axis: time line 1: starch (straight line in middle of graph) line 2: water (positive slope that crosses line 1 and levels out above line 1) line 3: glucose (negative slope that does the inverse of line 2)