BIO -CHEM -Exam 1 Quiz -Self Study Exam with Complete Solutions

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A bacterium that normally grows at room temperature (~ 25 °C) suddenly finds itself in a hot spring that is 75 °C? Which of the following is most likely to be true for that bacterium? A) Its prote... ins will lose their primary structure. B) Its nucleic acid strands will lose their polarity. C) Its peptide bonds will likely break. D) Its proteins will lose their quaternary structure. E) Its membranes will be covalently linked together for stabilization. - ANSWER D Which of the following statements about the nuclear envelope are true? A) It is continuous with the endomembrane system. B) It is made of a single membrane with nuclear pores. C) It is continuous with the nucleolus. D) It is connected to the plasma membrane. - ANSWER A In looking at the following molecules, which would contain polar covalent bonds? 1. COOH 2. O2 3. HCN 4. CH3 5. NH3 A) 1, 2, 3, and 5 only B) 1, 3, and 5 only C) 1 and 3 only D) 2, 3, and 5 only E) 2 and 4 only - ANSWER B A hydrolysis reaction: A) Usually results in increased entropy. B) Is rarely an enzyme-mediated reaction in cells. C) Tends to occur slowly in a humid environment. D) Is a reaction in which the products have more free energy than the reactants. E) Tends to happen more efficiently at lower temperatures. - ANSWER A Which statement about diffusion is false? A) Diffusion is an example of passive transport B) Diffusion results in a net movement of molecules from high to low concentrations. C) Diffusion does not require an input of energy. D) All types of molecules are able to diffuse across the plasma membrane. - ANSWER D Louis Pasteur sterilized a flask of media and then extended the neck of the flask so that bacteria and other organisms could not fall into the media. Which part of cell theory was he testing? A) That all prokaryotic cells are related to other prokaryotic cell and eukaryotic cells are related to other eukaryotic cells B) That all cells are fundamentally similar to each other C) That all cells come from pre-existing cells D) That some organisms are single-celled microbes while others are multi-cellular E) That cells are the functional unit of life and can do all the things necessary to support life - ANSWER C Which of the following is NOT, or does NOT contain a monosaccharide? A) Cellulose B) Triglycerides C) Deoxyribose D) RNA E) Peptidoglycan - ANSWER B Which of the following statements about competitive inhibitors is false? A) A competitive inhibitor often resembles the natural substrate. B) A competitive inhibitor decreases the Vmax of a reaction. C) A competitive inhibitor binds to the active site. D) A competitive inhibitor increases the Km of the reaction. - ANSWER B You are running an enzyme catalyzed reaction. The Vmax for the reaction is 60 mM/min and the Km is 20 nm substrate. You double the enzyme concentration and run the experiment again. What would you expect your Vmax and Km values to be with increased enzyme? A) Vmax: 60; Km: 20 B) Vmax: 120; Km: 20 C) Vmax:60; Km: 40 D) Vmax:120; Km: 40 E) Vmax: 120; Km:10 - ANSWER B Which of the following correctly matches an organelle with its function? A) Ribosome; lipid synthesis B) Lysosome; movement C) Nucleus; glycosylation D) Rough endoplasmic reticulum; protein synthesis E) Central vacuole; photosynthesis - ANSWER D Phospholipids can form lipid bilayers whereas fatty acids do not. What characteristic of phospholipids allows them to form lipid bilayers? A) Phospholipids are largely hydrophobic. B) Phospholipids contain polar head groups. C) Phospholipids contain a long hydrocarbon chain. D) Phospholipids can be unsaturated or saturated. - ANSWER B Which one of the following is not a function of carbohydrates? A) Energy storage B) Catalysis C) Energy source - ANSWER B An enzyme is able to metabolize two similar sugars. The Km for sugar A is 15 mM while the Km for sugar B is 20 mM. Which statement is true about this information? A) The enzyme has a higher affinity for sugar B. B) The enzyme is more efficient at metabolizing sugar B than sugar A. C) The concentration of sugar A needed to reach Vmax is 15 mM. D) The enzyme is more efficient at metabolizing sugar A than sugar B. - ANSWER D There are 3 major domains of life. Cells from which domain(s) have membranes made from phospholipids? A) Bacteria B) Eukarya C) Archaea, Bacteria, and Eukarya D) Mammals E) Archaea - ANSWER C What types of secondary structures are commonly found in proteins? A) α helix and β pleated sheet B) α helix and secondary hydrogen bonding C) β pleated sheet and secondary hydrogen bonding D) Hydrogen bonding and quaternary interactions - ANSWER A Which of the following reactions could be coupled to ATP hydrolysis to make it energetically favorable or spontaneous? ("to" is equivalent to an arrow) A) Glucose-1 phosphate + H2O to glucose + Pi ΔG= -5.0 B) Creatine phosphate + H20 to creatine + Pi ΔG = -3.0 C) Glucose + Pi to glucose-6 phosphate + H20 ΔG= +9.4 D) Glutamic acid + NH3 to glutamine ΔG=+3. - ANSWER D Which of the following is a similarity between desmosomes and tight junctions? A) Proteins are involved that link cells together. B) They allow the passage of large molecules from one cell to another. C) They are only found in epithelial cells. D) They allow the passage of small molecules from one cell to another. - ANSWER A If an atom has a charge of +2, which of the following must be true? A) It has at least three valence electrons B) It has less protons than it has electrons C) It has two more protons than neutrons D) It has less electrons than it has protons - ANSWER D Non-competitive inhibitors A) bind to the enzyme at the active site. B) can decrease the energy of activation. C) can activate an enzyme. D) bind to an enzyme at a site different than the active site. - ANSWER D Which statement is true about a protein's quaternary structure? A) The primary amino acid sequence of a protein is referred to as its quaternary structure B) More than one polypeptide subunit is required. C) Quaternary structures refers to a protein's two dimensional shape D) All polypeptides involved in quaternary structure must be the same - ANSWER B Which of the following is true of nucleic acid molecules? A) In a double stranded DNA molecule purines hydrogen bond to pyrimidines B) The ribose sugar never has a 2' OH C) A DNA molecule that contains mostly A-T pairs would be more heat resistant than a DNA molecule that contains mostly G-C pairs D) Phosphodiester bonds are formed by hydrolysis reactions for both DNA and RNA E) If you know the amount of adenine in a single strand of RNA, you can determine the amount of thymine in that same strand - ANSWER A You are studying a metabolic enzyme that is found in organisms living at extremely high temperatures and an acidic environment. You carry out your reactions on your lab bench at room temperature in water and find that the reaction is quite slow, even though you are able to reach a Vmax. Which of the following is not a good way to increase the rate of the reaction? A) Add more enzyme to the reaction. B) Increase substrate concentration. C) Decrease the pH of the reaction solution. D) Increase the temperature. - ANSWER B Students taking Bio 173, are studying an enzyme catalyzed reaction where the enzyme polyphenoloxidase binds to the substrate catechol and catalyzes the formation of the product ortho-quinone. If a competitive inhibitor "X" was added, which of the following is true? A) "X" binds to the regulatory site of polyphenoloxidase B) "X" binds to polyphenoloxidase by ionic interactions C) The Vmax of the reaction is lower in the presence of "X" D) Inhibition by "X" is decreased by increasing catechol concentration E) The Km of polyphenoloxidase is the same for catechol and "X" - ANSWER D Which of the following is an example of primary active transport? A) A small hydrophobic molecule diffuses across the lipid bilayer. B) Water moves down its concentration gradient through aquaporins. C) ATP directly transfers energy to the Na+/K+ pump to transport ions across the membrane. D) Glucose enters a cell using facilitated diffusion. - ANSWER C If all of the actin proteins in a cell were to become permanently denatured, which of the following would be directly affected? A) Tight junction formation B) Cytoplasmic streaming C) Production of ATP by mitochondria D) Primary structure of integrin E) Chaperone production - ANSWER B Which of the following is part of cell theory? A) Most organisms are multicellular B) All cells contain DNA C) All cells have unique metabolic strategies D) All cells have phospholipid bilayers surrounding their nucleus E) Unicellular organisms can spontaneously arise - ANSWER B Exergonic reactions A) have a negative ∆G. B) consume energy. C) have a positive ∆G. D) do not occur spontaneously. - ANSWER A Which of the following best summarizes the relationship between condensation reactions and hydrolysis reactions? A) condensation reactions break covalent bonds, hydrolysis breaks hydrogen bonds B) condensation assembles polymers and hydrolysis breaks down polymers C) hydrolysis creates monomers and condensation reactions break down polymers D) condensation reactions are the same as hydrolysis reactions - ANSWER B When cytosine makes a basepair, three hydrogen bonds are formed. When adenine makes a base pair, 2 hydrogen bonds are formed. In a DNA molecule that contains 8 total basepairs, three of which are guanine bases, how many total hydrogen bonds would be holding the 2 strands of DNA together? A) 16 B) 9 C) 24 D) 19 E) 0 - ANSWER D Which of the following statements is true about allosteric enzymes? A) Allosteric enzymes are regulated when a substance B) Allosteric enzymes can be both negatively and positively regulated. C) Allosteric enzymes can only be negatively regulated. D) Allosteric enzymes can only be positively regulated. - ANSWER B In a small stretch of a double stranded DNA molecule, there are a total of 8 nucleotide base pairs. If 3 of the bases were guanines and 5 of the bases were adenines, how many hydrogen bonds would be holding this molecule together? A) 16 B) 21 C) 8 D) 19 - ANSWER D At room temperature, how does cholesterol affect the plasma membrane? A) It reduces the mobility of phospholipids. B) It increases membrane fluidity. C) It decreases the phospholipid head groups from interacting with water. D) It increases the Van der Waals forces between hydrocarbon tails. - ANSWER A Which of the following is NOT a function of the endomembrane system? A) Phagocytosis B) Digestion of damaged organelles C) Protein modification D) ATP production E) Protein export - ANSWER D A common delivery method for getting drugs into cells is to surround the drug with a lipid bilayer called a liposome. How do you think this allows the drugs to enter the cell? A) The liposome cuts a hole in the cell and allows the drug to enter the cell B) The entire liposome and drug complex move into the cell by simple diffusion C) The liposome fuses with the phospholipid bilayer of cells that results in the drug being delivered into the cell D) The drug breaks down the liposome and diffuses into the cell E) The liposome is moved into the cell via active transport using a transporter that all cells have - ANSWER C If a red blood cell is placed in a hypertonic solution, what will happen? A) The red blood cell transports ions out of the cell. B) Nothing C) The red blood cell will shrink. D) The red blood cell will swell - ANSWER C Which of the following organelles harnesses energy in a eukaryotic cell? A) Cytoskeleton B) Golgi apparatus C) Mitochondrion D) Lysosome - ANSWER C What is the correct pairing between nucleotide bases? A) A-T and G-U B) A-G and T-C C) A-T and G-C D) A-C and G-T - ANSWER C In polymerization of nucleic acids, the next incoming nucleotide is added to the _____________ of the previous nucleotide A) 2'-OH B) 3'-phosphate C) 3'-OH D) 5'-phosphate - ANSWER C All of the following are true of protein denaturation except that it A) can be caused by changes in temperature B) can be caused by changes in pH C) results in a change in protein conformation D) is always irreversible - ANSWER D Which functional group is not found in proteins? A) Carboxyl B) Carbonyl C) Phosphate D) Amino - ANSWER C Which statement about a chemical reaction's transition state is false? A) The transition state is highly unstable. B) An input of energy is required for reactants to reach the transition state. C) During the transition state, chemical bonds are breaking and new ones are forming. D) Enzymes do not affect the energy required to reach the transition state. - ANSWER D Which of the following is NOT part of cell theory? A) Unicellular organisms arise from preexisting cells B) New cells come from preexisting cells C) Most organisms on Earth are multicellular D) Cells are the functional unit of life E) All organisms are composed of cells - ANSWER C Which of the following statements is true? A) Spontaneous reactions have a negative ∆G. B) Spontaneous reactions occur at a rapid rate. C) Endergonic reactions have a negative ∆G. D) Non-spontaneous reactions only need enzymes for them to proceed forward. - ANSWER A Hydrogen bonds are formed in each of the following situations EXCEPT A) Between purines and pyrimidines in a DNA molecule B) In the formation of alpha helical secondary structure of a protein [Show More]

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