AP Biology MCQ Practice

Researchers propose a model to explain variation in phytoplankton cell sizes in a marine environment. They base their model on the idea that smaller cells absorb nutrients more efficiently. The researchers predict that the mean diameter of phytoplankton cells will change by 50 micrometers for every 5-kilometer increase in distance from the shore because of a gradual decrease in nutrient availability. To test their model, the researchers determine that the phytoplankton cells found closest to shore have a mean diameter of 900 micrometers. Based on the model, what will be the mean diameter of the phytoplankton cells that are found 25 kilometers from shore? A. 650 micrometers B. 875 micrometers C. 925 micrometers D. 1150 micrometers

A. 650 micrometers

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? A. By passive transport from an area of low osmolarity to an area of high osmolarity B. By passive transport from an area of high osmolarity to an area of low osmolarity C. By active transport from an area of low osmolarity to an area of high osmolarity D. By active transport from an area of high osmolarity to an area of low osmolarity

A. By passive transport from an area of low osmolarity to an area of high osmolarity

Two different models of a living cell are represented in the figure. Of the two cells represented in the figure, which would likely be more efficient at exchanging substances with the surrounding environment? A. Cell A, because it has the larger surface-area-to-volume ratio. B. Cell A, because it has the smaller surface-area-to-volume ratio. C. Cell B, because it has the larger surface-area-to-volume ratio. D. Cell B, because it has the smaller surface-area-to-volume ratio.

A. Cell A, because it has the larger surface-area-to-volume ratio.

All eukaryotic cells contain at least one Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum. Which of the following best describes a process that occurs within the Golgi complex? A. Enzymatic modification of newly synthesized integral membrane proteins B. Synthesis of cytosolic proteins based on the nucleotide sequences of mRNAs C. Degradation of proteins by hydrolytic enzymes contained within the complex D. Synthesis of various types of lipids

A. Enzymatic modification of newly synthesized integral membrane proteins

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.

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? A. Repeat the process with other salt concentrations. B. Develop a model to explain why the cells react differently to different salt concentrations. C. Repeat the process using red blood cells from other animals. D. Develop an experimental procedure that uses a stain that makes the organelles of red blood cells more visible.

A. Repeat the process with other salt concentrations.

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.

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.

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.

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? A. It was mostly incorporated into nucleic acids that store the biological information. B. It was mostly incorporated into proteins that regulate and manage metabolic reactions. C. It was mostly incorporated into lipids that help separate cells from their surrounding environment. D. It was mostly incorporated into carbohydrates that form protective structures outside the cells.

B. It was mostly incorporated into proteins that regulate and manage metabolic reactions.

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.

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.

B. The animal's body cells are defective in endocytosis.

The figure shows a process by which a cell might absorb food from its surrounding environment and break it down for use as a source of energy and matter. The process involves lysosomes, which are membrane-bound organelles that contain hydrolytic enzymes. Activation of the hydrolytic enzymes requires an acidic pH, and lysosomes maintain an internal acidic pH by using ion pumps. 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.

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. 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 Na+ 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 Na+−K+ pump moving more K+ ions into the cell. D. The membrane potential will be maintained by the diffusion of Na+ ions into the cell.

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

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? A. The chloroplast, since all organisms need a source of energy. B. The ribosome, since all organisms need to synthesize proteins. C. The mitochondrion, since all organisms need to break down glucose. D. The cell wall, since all marine organisms need them for support.

B. The ribosome, since all organisms need to synthesize proteins.

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

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 move 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.

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 in 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 in the occurrence of uncontrolled chemical reactions.

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.

Which procedure should be done next to gather data needed to meet the scientist's objective? A. Incubate samples with the same four ATP concentrations at 30°C. B. Incubate samples containing 5.0μm/mL of ATP at four temperatures other than 25°C. C. Incubate samples containing 1.0μm/mL of ATP at four temperatures other than 25°C. D. Incubate samples containing 1.0μm/mL of ATP at 25°C and determine the rate of transport for four other proteins.

C. Incubate samples containing 1.0μm/mL of ATP at four temperatures other than 25°C.

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. 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

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? A. The ratio is 0.45, and the cells are more efficient at transferring oxygen. B. The ratio is 1.12, and the cells are less efficient at transferring oxygen. C. The ratio is 0.89, and the cells are less efficient at transferring oxygen. D. The ratio is 141, and the cells are more efficient at transferring oxygen.

C. The ratio is 0.89, and the cells are less efficient at transferring oxygen.

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. 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 and 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.

C. 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.

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.

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

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. Which of the following claims about the origin of the euglenid chloroplast is best supported by the three-membrane structure of the envelope? A. It originated from the spontaneous assembly of organic molecules into a lipid bilayer inside a free-living prokaryote. B. It originated from the fusion of the plasma membranes of two different free-living photosynthetic prokaryotes. C. It originated from the incorporation of a photosynthetic prokaryote into a eukaryotic cell by a single endosymbiotic event. D. It originated from the incorporation of a photosynthetic prokaryote into a eukaryotic cell by two endosymbiotic events.

D. It originated from the incorporation of a photosynthetic prokaryote into a eukaryotic cell by two endosymbiotic events.

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.

Cells contain smaller components called organelles that are necessary for a cell's survival. Organelle functions have often been compared to components of larger systems. Which of the following functional differences between the rough and smooth endoplasmic reticulum (ER) is explained by the structural differences between them? A. Rough ER breaks down toxic substances, and smooth ER only transports them out of the cell. B. Rough ER can synthesize and package lipids for export, and smooth ER cannot. C. Rough ER can produce ATP, and smooth ER cannot. D. Rough ER can synthesize and package proteins for export, and smooth ER cannot.

D. Rough ER can synthesize and package proteins for export, and smooth ER cannot

A spherical bacterial cell has a radius of 3μm. The human egg cell has a radius of 100μm. Which statement correctly indicates the cell that is able to more efficiently exchange materials with the external environment and provides a correct explanation? A. The egg cell, because it has the smallest surface-to-volume ratio. B. The egg cell, because it has the largest surface-to-volume ratio. C. The bacterial cell, because it has the smallest surface-to-volume ratio. D. The bacterial cell, because it has the largest surface-to-volume ratio.

D. The bacterial cell, because it has the largest surface-to-volume ratio.

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? A. The production and secretion of steroids B. The destruction of toxic materials produced in other cells of the organism C. The synthesis of polysaccharides for energy storage D. The production and secretion of proteins

D. The production and secretion of proteins