front 1 Which is a major function of the plasma membrane? a. Storing calcium ions b. Storing organic chemicals for metabolism c. Providing genetic information d. Generating ATP e. Regulating the passage of molecules into and out of the cell | back 1 e. Regulating the passage of molecules into and out of the cell |
front 2 The cell membrane is composed mainly of a. cytosol. b. phospholipids and proteins. c. phospholipids and nucleic acids. d. water. e. proteins and glycocalyx. | back 2 b. phospholipids and proteins. |
front 3 Which organelles would you expect to be especially numerous in cells such as muscle cells that have a tremendous demand for energy in the form of ATP? a. Peroxisomes b. Endosomes c. Lysosomes d. Ribosomes e. Mitochondria | back 3 e. Mitochondria |
front 4 Which is true about the structure and function of a gene? a. It is an uncoiled protein that contains information necessary for the synthesis of other proteins. b. It is a sequence of nucleotides in DNA that acts as an enzyme to digest proteins. c. It is composed of many molecules of DNA and contains information needed to make RNA. d. It is a sequence of nucleotides in DNA that contains information necessary for the synthesis of proteins. | back 4 d. It is a sequence of nucleotides in DNA that contains information necessary for the synthesis of proteins. |
front 5 RNA synthesis from a DNA template a. is called translation of the message. b. requires DNA polymerase. c. is called transcription of the message. d. occurs in the nucleolus. e. occurs in the cytoplasm | back 5 c. is called transcription of the message. |
front 6 What is the term for the segments of primary RNA that are cleaved and discarded by spliceosomes? a. Codons b. Introns c. Exons d. Anticodons e. Genes | back 6 b. Introns |
front 7 Which is the best definition of the term ligand? a. A receptor composed of protein b. A molecule or ion that binds to a protein c. Any molecule found in the intracellular fluid d. Any molecule found in the extracellular fluid e. A carbohydrate molecule that binds weakly to membrane phospholipids | back 7 b. A molecule or ion that binds to a protein |
front 8 What is the defining characteristic of an allosteric protein? a. They contain two polypeptide chains, with each being an exact mirror image of the other. b. They contain only one ligand-binding site, but because the specificity is low, many different ligands can bind to it. c. They contain two ligand-binding sites, one that activates the protein when a ligand binds, and the other that inactivates the protein when the same ligand binds. d. They contain more than one ligand-binding site, and noncovalent binding of a ligand to one site alters the shape of other ligand-binding sites. e. They contain no binding sites of their own, but act by modulating the activity of other proteins. | back 8 d. They contain more than one ligand-binding site, and noncovalent binding of a ligand to one site alters the shape of other ligand-binding sites. |
front 9 Which of these covalently modifies proteins by phosphorylation? a. Enzymes called protein phosphatases b. Other proteins called allosteric proteins c. Any ligand that can bind to specific binding sites d. Enzymes called protein kinases e. Metal ions, such as Fe2+ | back 9 d. Enzymes called protein kinases |
front 10 How does a chemical catalyst increase the rate of a reaction? a. By acting as one of the reactant molecules b. By decreasing the energy of activation c. By increasing the energy content of the product molecules d. By increasing the temperature of a solution e. By phosphorylating a reactant | back 10 b. By decreasing the energy of activation |
front 11 What is a coenzyme? a. An organic cofactor that directly participates as one of the substrates in an enzymatic reaction b. A metal, such as zinc, that participates in enzymatic reactions c. A term regarding enzymatic reactions that is synonymous with "cofactor" d. Any ligand that binds to a specific site on a protein receptor e. An inorganic molecule that catalyzes enzymatic reactions | back 11 a. An organic cofactor that directly participates as one of the substrates in an enzymatic reaction |
front 12 A certain protein receptor is capable of binding the neurotransmitter epinephrine but does not bind to the neurotransmitters dopamine, glutamate, or serotonin. This is because the receptor displays what characteristic? a. Saturation b. Inhibition c. Specificity d. Acclimatization e. Accommodation | back 12 c. Specificity |
front 13 Which of the following is true concerning the rate-limiting step in a metabolic pathway? a. It is likely to be the slowest reaction in the pathway, and it is always the last step in a metabolic pathway. b. It is likely to be the fastest reaction in the pathway, and it is always the last step in a metabolic pathway. c. It is always the first step in the pathway, and may be subject to end-product inhibition. d. It is likely to be the slowest reaction in the pathway, and it may be subject to end-product inhibition. e. It is likely to be the fastest reaction in the pathway, and it may be subject to end-product inhibition. | back 13 d. It is likely to be the slowest reaction in the pathway, and it may be subject to end-product inhibition. |
front 14 ATP is a. formed during the hydrolysis of ADP. b. used by cells for the storage of energy. c. used to transfer energy within a cell. d. a protein. e. a molecule with less total energy content than ADP. | back 14 c. used to transfer energy within a cell. |
front 15 ATP is a. a nucleotide. b. a lipid. c. an amino acid. d. a carbohydrate. e. a steroid. | back 15 a. a nucleotide. |
front 16 Which is a series of reactions by which fatty acid catabolism occurs? a. Glycolysis b. Lipogenesis c. Beta-oxidation d. Glycogenolysis e. Phosphorylation | back 16 c. Beta-oxidation |
front 17 Which describes the action of a ligand's competitive antagonist? a. It decreases the amount of ligand required to activate the protein. b. It blocks the binding of the ligand to its binding site and prevents activation of the protein. c. It binds to a different binding site on the protein, altering the protein shape so that a ligand cannot bind. d. When present, it increases the binding of a ligand to its receptor. | back 17 b. It blocks the binding of the ligand to its binding site and prevents activation of the protein. |
front 18 You are learning about an integral membrane protein. This protein has a region that is exposed to the extracellular fluid, a region that spans the membrane, and another region that is exposed to the intracellular fluid. Which of the following is likely TRUE of this protein? a. It is a polar molecule. b. It is a nonpolar molecule. c. It is an amphipathic molecule. | back 18 c. It is an amphipathic molecule. |
front 19 Macrophages are cells that engulf and digest bacteria and cell debris. To perform the digestive function, macrophages tend to have more __________ than other cells. a. peroxisomes b. endosomes c. lysosomes d. ribosomes e. mitochondria | back 19 c. lysosomes |
front 20 A solution containing proteins of a particular type is exposed to the same concentrations of ligands X and Y, but the percent saturation of molecule X is greater than the percent saturation of molecule Y. Which is most likely to be a true statement? a. The binding sites for ligand X are 100% saturated. b. The binding sites for ligand X have greater specificity than the binding site for ligand Y. c. Ligand X must be a competitive inhibitor of ligand Y. d. Both ligands must bind to the same binding site on the protein. e. The protein has a higher affinity for ligand X than for ligand Y. | back 20 e. The protein has a higher affinity for ligand X than for ligand Y. |
front 21 Two receptors, A and B, can bind the same chemical signaling molecules but the concentration of those molecules required to reach 50% saturation is twice as great for receptor B. Therefore, the receptors have the same __________, but different __________. a. specificity; affinity b. specificity; saturation c. affinity; specificity d. affinity; competition e. competition; affinity | back 21 a. specificity; affinity |
front 22 Many popular diet trends involve severe reductions in dietary carbohydrates so that the body must utilize fats and lipids as energy sources. Under these conditions, which of the following would be an enhanced entry pathway in cellular respiration? a. Glycolysis b. Krebs cycle c. Oxidative phosphorylation d. Cellular respiration could begin with any of these processes. | back 22 b. Krebs cycle |
front 23 Macrophages are cells that engulf and digest bacteria and cell debris. To perform the digestive function, macrophages tend to have more __________ than other cells. a. peroxisomes b. endosomes c. lysosomes d. ribosomes e. mitochondria | back 23 c. lysosomes |
front 24 Two receptors, A and B, can bind the same chemical signaling molecules but the concentration of those molecules required to reach 50% saturation is twice as great for receptor B. Therefore, the receptors have the same __________, but different __________. a. specificity; affinity b. specificity; saturation c. affinity; specificity d. affinity; competition e. competition; affinity | back 24 a. specificity; affinity |
front 25 You are learning about an integral membrane protein. This protein has a region that is exposed to the extracellular fluid, a region that spans the membrane, and another region that is exposed to the intracellular fluid. Which of the following is likely TRUE of this protein? a. It is a polar molecule. b. It is a nonpolar molecule. c. It is an amphipathic molecule. | back 25 c. It is an amphipathic molecule. |
front 26 Macrophages are motile cells that crawl within tissues of the cells. Hepatocytes are stationary cells that are anchored in place within the tissue. Compared to hepatocytes, macrophages would likely have more of which cytoskeletal filament? a. Actin filaments b. Intermediate filaments c. Microtubules d. Myosin filaments e. Cilia | back 26 a. Actin filaments |
front 27 You’re researching a steroid hormone that binds to a receptor inside the cell. Once the receptor binds to its hormone, the receptor moves into the nucleus of the cell. The result of hormone-receptor binding is that new mRNA molecules are made. The receptor is also a a. ribosome. b. transcription factor. c. tRNA molecule. d. promoter. e. splicosome. | back 27 b. transcription factor. |
front 28 Cyanide is a molecule that binds irreversibly to and acts as an allosteric inhibitor for one of the cytochromes in the electron transport chain. Which of the following molecules would you see increased in the cells of a person suffering from cyanide poisoning? a. ATP b. Glucose c.. Pyruvate d. NAD+ e. NADH | back 28 e. NADH |
front 29 Many popular diet trends involve severe reductions in dietary carbohydrates so that the body must utilize fats and lipids as energy sources. Under these conditions, which of the following would be an enhanced entry pathway in cellular respiration? a. Glycolysis b. Krebs cycle c. Oxidative phosphorylation d. Cellular respiration could begin with any of these processes. | back 29 b. Krebs cycle |
front 30 Tamoxifen is a breast-cancer drug that binds to the estrogen receptor. When in the body, tamoxifen binds to the estrogen receptor for much longer than the patient’s own estrogen. Tamoxifen stays bound for so long that it prevents the binding of circulating estrogen to its receptor. Tamoxifen must have a higher __________ for the estrogen receptor than estrogen. a. saturation b. inhibition c. specificity d. affinity e. accommodation | back 30 d. affinity |