A group of mutations, known as MT-ND1, have been identified in mitochondrial DNA. These mutations are associated with a number of debilitating diseases stemming from the production of nonfunctional proteins in the mitochondria. Show
A-The cell is unable to synthesize most proteins required for normal cell functions. D-The cell is unable to complete reactions related to electron transport and ATP production. Figure
1. Simplified diagram of a euglenid, showing the structure of the chloroplast envelope A-It originated from the spontaneous assembly of organic molecules into a lipid bilayer inside a free-living prokaryote. D-It originated from the incorporation of a photosynthetic prokaryote into a eukaryotic cell by two endosymbiotic events. Testosterone is a small steroid hormone that is important in cell signaling. Which of the following indicates where testosterone enters a cell and why it is able to cross at that point? A- 1, because testosterone is nonpolar and can diffuse through the membrane. A- 1, because testosterone is nonpolar and can diffuse through the membrane. Beetroot cells contain a family of dark red pigments called betalains. The selectively permeable nature of the beetroot cells keeps the internal environment of the cell separate from the external environment of the cell. Researchers are interested in determining whether the selective permeability of beetroot cells is due to the cell membrane or if
it is due to the cell wall. A-When beetroot cells are placed in a solution with cellulase, the solution turns dark red. B-When beetroot cells are placed in a solution with cellulase, the solution remains clear. Stomata are pores on the surfaces of the leaves and
stems of plants that regulate gas exchange between the plants and the atmosphere. A-The ratio decreases from 0.860.86 to 0.630.63, because fewer stomata are needed at higher CO2CO2 concentrations. A-The ratio decreases from 0.860.86 to 0.630.63, because fewer stomata are needed at higher CO2CO2 concentrations Which of the following transport mechanisms will be affected most directly by a temporary shortage of ATPATP molecules inside the cell? A-The movement of water molecules through aquaporins C-The transport of glucose molecules against a concentration gradient Hereditary spherocytosis (HS)(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 7.2μm7.2μm, and the average diameter of red blood cells in a person with HSHS was found to be 6.7μm6.7μm. The normal red blood cell has an average surface area of 136μm2136μm2 and an average volume of 9.1μm 391μm3. A-The ratio is 0.45, and the cells are more efficient at transferring oxygen. C-The ratio is 0.89, and the cells are less efficient at transferring oxygen. 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. A-Repeat the original experiment, but at three different temperatures. Compare the transport rates among the three temperatures. D-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. A scientist is studying the various prokaryotic and eukaryotic species found floating in a sample of water taken from a marine ecosystem. A-The chloroplast, since all organisms need a source of energy. B-The ribosome, since all organisms need to synthesize proteins. 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. 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. 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. A-The valinomycin treatment caused an increase in the activity of the rough endoplasmic reticulum. ... Lysosomes digest food particles brought into a cell by endocytosis. After a vesicle containing food particles fuses with a lysosome, H+ ions are transported into the
lysosome from the cytosol. This significantly lowers the pHpH of the lysosome relative to the cytosol and activates the enzymes that digest the particles. A-The lysosomal enzymes will not become active, since there will be no active transport of H+ ions. A-The lysosomal enzymes will not become active, since there will be no active transport of H+ ions. The figure shows a representation of a protein embedded in a
cell membrane. The numbers indicate different structural regions of the protein. A-Region 1 is hydrophilic because it interacts with the interior of the membrane, whereas region 2 is hydrophobic because it interacts with an aqueous environment. B-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. 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. A-By passive transport from an area of low
osmolarity to an area of high osmolarity A-By passive transport from an area of low osmolarity to an area of high osmolarity 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. A-The smooth endoplasmic reticulum C-The lysosome 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. A-Actual cell
membranes have a much thicker phospholipid bilayer than the artificial membrane does. B-Actual cell membranes have a variety of proteins embedded in the membrane that are absent in the artificial membrane. Which of the following observations best supports the claim that mitochondria evolved from once-free-living prokaryotic cells by the process of endocytosis? A-Mitochondria produce ATP. D-Mitochondria are surrounded by a double membrane. 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. A-By simple diffusion A-By simple diffusion Researchers have proposed a model of chloroplast evolution. According to the model, chloroplasts evolved from a small prokaryotic organism that was engulfed by an ancestral eukaryote. The engulfed prokaryote then formed an endosymbiotic relationship with the
eukaryotic host. A-Chloroplasts are separated from other subcellular compartments by semipermeable membranes. D-Chloroplasts and some prokaryotes share similar photosynthetic reactions. 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. A-Cell 1 B-Cell 2 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. A-The Na+ concentration outside the cell will increase. B-The Na+concentration inside the cell will increase.
The cell membrane is selectively permeable due to its structure. Thus, the internal environment of the cell is distinct from the external environment of the cell. One biologist hypothesizes that small nonpolar molecules readily pass through the membrane. Another biologist alternatively hypothesizes that these types of molecules require channel and transport proteins that are embedded in the membrane in order to move across the membrane. A-Ethanol is found in the cytosol of cells when they are briefly exposed to a ten percent ethanol solution. C-CO2 and N2 movement in and out of cells is unaffected when membrane protein activity is blocked. 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. A-Repeat the process with other salt concentrations. A-Repeat the process with other salt concentrations. Some viral infections can lead to the rupture of the lysosome membrane. Which prediction of the effect of this disruption of cellular compartmentalization is most likely correct? A-Enzymes will be released that will specifically target the virus. C-Hydrolytic enzymes will be released, which will cause cell death. A certain type of specialized cell contains an unusually large amount of rough endoplasmic reticulum (ER). A-The production and secretion of steroids D-The production and secretion of proteins In an experiment, researchers compared the growth of two different
plants, plant X and plant Y. The researchers maintained the plants under nearly identical conditions and observed that plant X grew faster than plant Y. The researchers also observed that the inner mitochondrial membranes of plant X had more folds than did those of plant Y. A-It increases the efficiency of photosynthesis, which
results in faster cell growth. B-It increases the surface area available for ATP production, which results in faster cell growth. 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. A-Incubate the cells in the absence of the protein. C-Incubate the cells in the presence of several different concentrations of the protein. Liver cells manufacture glycoproteins, while adipose cells store fat. Which of the following subcellular structures is likely to be more prominent in liver cells than in adipose cells? A-Nucleus B-Golgi apparatus Trypsinogen is split by the enzyme enterokinase to form an activated molecule of the protease trypsin. Which of the following would confirm that the activation of trypsin is an example of how a positive feedback mechanism can amplify a biological process? A-The activated trypsin enzyme can use enterokinase as a substrate B-The trypsin produced by the reaction is capable of splitting and activating additional trypsinogen molecules Which of the following statements is true regarding the movement of substances across cell membranes? A-Ions are unable to move through the phospholipid bilayer because the nonpolar tail regions of the phospholipids are hydrophobic A-Ions are unable to move through the phospholipid bilayer because the nonpolar tail regions of the phospholipids are hydrophobic If ATP breakdown (hydrolysis) is inhibited, which of the following types of movement across cell membranes is also inhibited? A-Movement of oxygen into a cell C-Passage of a solute against its concentration gradient Which of the following statements most directly supports the claim that different species of organisms use different metabolic strategies to meet their energy requirements for growth, reproduction, and homeostasis? D-Plants generally use starch molecules for storage while animals use glycogen and fats for storage 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 D-The production and secretion of proteins Membrane-bound organelles have been an important component in the evolution of complex, multi-cellular organisms. Which of the following best summarizes an advantage of eukaryotic cells having internal membranes? A-Eukaryotic cells are able to reproduce faster because of the presence of organelles C-Organelles isolate specific reactions increasing metabolic efficiency Hydrolysis is involved in which of the following? A-formation of starch, a polysaccharide, from monomers of glucose D-The digestion of sucrose, a disaccharide to its monomers of glucose and fructose Various macromolecules can be found embedded within the phospholipid bilayer. Which of the following uses passive transport without the help of proteins to move materials across the cell membrane? A-the
depolarization of a muscle cell D-the movement of carbon dioxide across the cell membrane What is the likely origin of chloroplasts?Mitochondria and chloroplasts likely evolved from engulfed prokaryotes that once lived as independent organisms. At some point, a eukaryotic cell engulfed an aerobic prokaryote, which then formed an endosymbiotic relationship with the host eukaryote, gradually developing into a mitochondrion.
Which of the following are the two main components of cellular membranes?What are two main components of a cell (plasma) membrane? Two main components are the phospholipid bilayer and the proteins.
Which of the following results best refutes the alternative hypothesis that selective permeability is a consequence of the cell wall?Which of the following results best refutes the alternative hypothesis that selective permeability is a consequence of the cell wall? When beetroot cells are placed in a solution with cellulase, the solution remains clear.
Which of the following represents the digestion center of the cell responsible for breakdown macromolecules and worn out organelles?Intercellular Junctions. |
Which of the following claims about the origin of the Euglena chloroplast is best supported by the three membrane structure of the envelope?
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