Ap bio

4. Which of the following best describes the numbered areas? A- Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules. B- Area 2 is polar, since water has been excluded from this area of the membrane. C- Areas 1 and 3 are hydrophilic, since membrane molecules formed covalent bonds with water. D- Area 2 is nonpolar, since hydrogen bonds between the adjacent lipids hold the membrane together.

A- Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules.

10. The illustration shows the active transport of hydrogen ions through a membrane protein. Which of the following best predicts the effect of not having ATP available to supply energy to this process? A- H+ ions will stop moving through the protein. B- H+ ions will move in the other direction through the protein. C- H+ ions will continue to move through the protein in the original direction but at a slower rate. D- H+ ions will begin to move through the phospholipid portion of the membrane in the original direction.

A- H+ ions will stop moving through the protein.

6. Figure 1. Phospholipid bilayer with transmembrane protein Which statement best explains why correct protein folding is critical in the transmembrane protein shown above? A- Interactions of the hydrophobic and hydrophilic amino acids help to anchor the protein in the membrane. B- Interactions of the peptide bonds of the protein with the membrane will affect the rate at which substances can cross the membrane. C- Interactions of the protein and phospholipids increase membrane fluidity. D- Interactions of the quaternary structure of the protein will increase hydrogen bonding in the membrane and make the membrane less fluid.

A- Interactions of the hydrophobic and hydrophilic amino acids help to anchor the protein in the membrane.

22. Cholesterol is an important component of animal cell membranes. Cholesterol molecules are often delivered to body cells by the blood, which transports the molecules in the form of cholesterol-protein complexes. The complexes must be moved into the body cells before the cholesterol molecules can be incorporated into the phospholipid bilayers of cell membranes. 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? A- The animal's body cells are defective in exocytosis. B- The animal's body cells are defective in endocytosis. C- The animal's body cells are defective in cholesterol synthesis. D- The animal's body cells are defective in phospholipid synthesis.

A- The animal's body cells are defective in exocytosis.

8. A team of biologists develop a new drug, and one team member hypothesizes that the drug is incapable of freely passing across the plasma membrane and requires the help of membrane proteins to enter cells. Alternatively, another biologist on the team hypothesizes that the drug can diffuse passively across the plasma membrane like O2 and CO2 can. 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? A- The drug is a small nonpolar molecule. B- The drug is a small charged molecule. C- The drug is a large polar molecule. D- The drug is a large charged molecule.

A- The drug is a small nonpolar molecule.

13. Muscle cells have high ATP demands. Which of the following is a scientific claim about how the structure of the mitochondria in muscle cells should be different than it is in other cells because of the high energy demands of mitochondria? A- The inner membrane of the mitochondria in muscle cells should have more folds to increase the surface area, allowing more ATP to be synthesized. B- The inner membrane of the mitochondria in muscle cells should be more permeable to large enzymes, allowing the same reactions to occur in both compartments of the mitochondria. C- The outer membrane of the mitochondria in muscle cells should be thicker, allowing more rapid diffusion of molecules into the mitochondria. D- The outer membrane of the mitochondria of muscle cells should have more folds, increasing the surface area for faster diffusion of molecules from the cytoplasm.

A- The inner membrane of the mitochondria in muscle cells should have more folds to increase the surface area, allowing more ATP to be synthesized.

14. Which of the following claims is scientifically accurate and consistent with an observation that a decrease in lysosome production within a cell leads to a decline in mitochondrial activity? A- A lack of lysosomes will cause a decrease in the synthesis of enzymes necessary for cellular respiration. B- Fewer lysosomes will be available to break down macromolecules to provide the necessary nutrients for cellular respiration. C- Fewer lysosomes will be available to store materials required for the functioning of the mitochondria. D- Lysosomes will not be available to modify proteins so that they are targeted to the mitochondria.

B- Fewer lysosomes will be available to break down macromolecules to provide the necessary nutrients for cellular respiration.

9. Plant cell walls are composed of cellulose, while fungal cell walls are composed of chitin. A group of scientists hypothesize that this difference means the cell wall has largely different functions in plant cells and fungal cells. Alternatively, another group of scientists hypothesize that despite their biochemical differences, plant and fungal cell walls serve similar functions. Which of the following observations would best support the alternative hypothesis described above? A- Plant cell walls are found just outside the plasma membrane, while fungal cell walls are found just beneath the plasma membrane. B- In both plant cells and fungal cells, the cell wall surrounds the outside of the cell membrane. C- Some plant cells have secondary cell walls that confer additional rigidity, while fungal cells do not. D- Photosynthesis occurs in plant cells, but it does not occur in fungal cells.

B- In both plant cells and fungal cells, the cell wall surrounds the outside of the cell membrane.

23. Which of the following statements best explains the processes of passive and active transport? A- 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. B- 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. C- 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. D- 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.

B- 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.

5. 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? A- The nonpolar portions of the phospholipid molecules are attracted to the internal and external environments. B- The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments. C- The embedded proteins attract the fatty acid tails of the phospholipids, so the tails point away from the internal and external aqueous environments. D- The fatty acid tails of the phospholipid molecules are hydrophilic and are repelled by the internal and external aqueous environments.

B- The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments.

2. Which of the following outcomes will most likely result from a loss of ion pump function in the cell's lysosomes? A- The internal pH of the lysosomes will decrease, which will prevent the activation of hydrolytic enzymes and interfere with the intracellular digestion of food. B- The internal pH of the lysosomes will increase, which will prevent the activation of hydrolytic enzymes and interfere with the intracellular digestion of food. C- The internal pH of the lysosomes will decrease, which will activate hydrolytic enzymes and enhance the intracellular digestion of food. D- The internal pH of the lysosomes will increase, which will activate hydrolytic enzymes and enhance the intracellular digestion of food.

B- The internal pH of the lysosomes will increase, which will prevent the activation of hydrolytic enzymes and interfere with the intracellular digestion of food.

12. A cell's membrane potential is maintained by the movement of ions into and out of the cell. A model showing the influence of membrane proteins on the movement of sodium (Na+) and potassium (K) ions across the plasma membrane is presented in Figure 1. Figure 1. Section of a cell's plasma membrane, showing ion concentrations and membrane proteins Based on the model presented in Figure 1, which of the following outcomes will most likely result from a loss of protein X function? A- The membrane potential will be disrupted by an increase in Nat concentration inside the cell. B- The membrane potential will be disrupted by an increase in K+ concentration inside the cell. C- The membrane potential will be maintained by the Nat K+ ions into the cell. pump moving more K+ D- The membrane potential will be maintained by the diffusion of Nations into the cell.

B- The membrane potential will be disrupted by an increase in K+ concentration inside the cell.

25. Organelles such as mitochondria and the endoplasmic reticulum have membranes that compartmentalize reactions and other metabolic processes. To function properly, the organelles must move substances across their membranes. Which of the following statements describes a feature shared by mitochondria and the endoplasmic reticulum that increases the efficiency of their basic functions? A- They have rigid, nonfluid membranes. B- They have highly folded membranes. C- They have membranes composed of many carbohydrates. D- They have double membranes, with one membrane enclosed within the other.

B- They have highly folded membranes.

11. Which statement best describes the effect on water transport across the cell membrane if the aquaporin in the figure ceases to function? A- Water molecules will no longer be able to Imove across the cell membrane. B- Water molecules will still be able to move across the cell membrane but at a slower rate. C- Water molecules will only be able to enter the cell by active transport. D- Water molecules will move across the cell membrane at a faster rate without the aquaporin regulating their flow.

B- Water molecules will still be able to move across the cell membrane but at a slower rate.

3. Which of the following statements best predicts the effect of increasing the permeability of the mitochondrial membranes to large molecules? A- ATP production will increase because of an increase in the rate at which proteins diffuse out of mitochondria. B- ATP production will increase because of an increase in the mixing of mitochondrial and cytosolic substances. C- ATP production will decrease because of an increase the occurrence of uncontrolled chemical reactions. D- ATP production will decrease because of an increase in the surface area of the mitochondrial membranes.

C- ATP production will decrease because of an increase the occurrence of uncontrolled chemical reactions.

19. 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? A- Add small nonpolar molecules to the extracellular space and measure the direction of particle movement of the molecules. B- Measure the rate of extracellular fluid movement into the intracellular space. C- Add more of the proteins to the plasma membrane and measure the rate of the particle movement. D- Remove ATP from the intracellular space and measure the rate of the particle movement into the intracellular space.

C- Add more of the proteins to the plasma membrane and measure the rate of the particle movement.

18. The endosymbiont theory proposes a model for the evolution of mitochondria. According to the model, an ancestral eukaryote engulfed a small, free-living prokaryotic organism. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host. Which of the following observations best supports the A- Prokaryotes and eukaryotes acquire nutrients from the surrounding environment. B- Organelles such as mitochondria and the endoplasmic reticulum have membranes composed of phospholipids. C- Mitochondria and some prokaryotes share similar metabolic reactions that produce ATP. D- Eukaryotes evolved after prokaryotes and have more complex structures.

C- Mitochondria and some prokaryotes share similar metabolic reactions that produce ATP.

16. 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. 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? A- The nucleus B- The plasma membrane C- The Golgi complex D- The extracellular space

C- The Golgi complex

15. Researchers claimed that a particular organelle originated from a free-living prokaryotic cell that was engulfed by a larger cell, as shown in Figure 1. Figure 1. A model showing a cell engulfing a smaller cell Which of the following provides evidence to best support the researchers' claim? A- The organelle has a phospholipid membrane. B- The organelle has protein in the membrane. C- The organelle has a double membrane. D- The organelle has an internal aqueous environment that is similar to the cytosol of the larger cell.

C- The organelle has a double membrane.

7. Aquaporins are channel proteins that facilitate the transport of water across the cell membrane. One group of researchers hypothesizes that without functional aquaporins, no water will be able to enter the cell. A different group proposes an alternative hypothesis, stating that even with nonfunctional aquaporins, a small amount of water will still cross the cell membrane. An experiment is set up in which plant cells with mutated (nonfunctional) aquaporins and plant cells with normally functioning aquaporins are both placed in distilled water. Which of the following data would support the alternative hypothesis? A- Cells with functional aquaporins exhibit low turgor pressure and are hypertonic. B- Cells with functional aquaporins exhibit high turgor pressure and are hypotonic. C- Cells with mutated aquaporins exhibit an absence of turgor pressure and are completely plasmolyzed. D- Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.

D- Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.

20. 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? A- Decreasing the salinity of the environment a little at a time until the ATP usage reaches a maximum B- Decreasing the salinity of the environment a little at a time until ATP usage reaches a minimum C- Increasing the salinity of the environment a little at a time until ATP usage reaches a maximum D- Increasing the salinity of the environment a little at a time until the ATP usage reaches a minimum

D- Increasing the salinity of the environment a little at a time until the ATP usage reaches a minimum

1. Changing the shape or morphology of the mitochondrial inner membrane can change the efficiency of mitochondrial function. Which of the following outcomes will most likely result from a change in the shape of the mitochondrial inner membrane from a highly folded surface to a smooth, flat surface? A- Mitochondria will become more efficient because the inner mitochondrial membrane will become more permeable to ions. B- Mitochondria will become more efficient because the total volume of the mitochondria will increase. C- Mitochondria will become less efficient because the inner mitochondrial membrane will become less permeable to large molecules. D- Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease.

D- Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease.

17. Which of the following statements best supports the claim that certain organelles within eukaryotic cells evolved from free-living prokaryotic cells? A- The cytoplasm of both eukaryotes and prokaryotes is surrounded by a plasma membrane. B- Eukaryotes and prokaryotes both contain ribosomes, but the ribosomes of eukaryotes are more complex in structure than those of prokaryotes. C- Eukaryotes exchange segments of internal membranes between the endoplasmic reticulum and Golgi apparatus, but prokaryotes have no such internal membranes. D- Some organelles contain their own DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell's nucleus.

D- Some organelles contain their own DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell's nucleus.

24. In an experiment, cells were isolated from an aquatic plant and suspended in pond water, a sucrose sugar solution, or distilled water. All of the cells were then viewed under a microscope. Compared with the cell in the pond water, the cell in the sugar solution appeared shriveled, and the cell in the distilled water appeared inflated. The results of the experiment are represented in Figure 1. Figure 1. The results of an experiment using aquatic plant cells Which of the following statements best explains the observations represented in Figure 1 ? A- 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. B- 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. C- There was a net movement of water out of the cell suspended in the sugar solution an a net movement of water into the cell suspended in the distilled water. D- 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.

D- 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.

21. 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 1.0 μm/mL. 0.2 μm/mL ATP 1.0 μm/mL ATP 2.0 um/mL ATP 5.0 μm/mL ATP Figure 1. The four ATP concentrations used in the experiment Which procedure should be done next to gather data needed to meet the scientist's objective? Opt 1- Incubate samples with the same four ATP concentrations at 30°C. Opt 2- Incubate samples containing 5.0 μm/mL of ATP at four temperatures other than 25˚C. Opt 3- Incubate samples containing 1.0 μm/mL of ATP at four temperatures other than 25˚C. Opt 4- Incubate samples containing 1.0 μm/mL of ATP at 25°C and determine the rate o transport for four other proteins.

Opt 3- Incubate samples containing 1.0 μm/mL of ATP at four temperatures other than 25˚C.