Biochemistry - Exam 1 Practice Questions

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Biochemistry - Exam 1 Practice Questions In a bacterial cell, the DNA is in the: A) cell envelope. B) cell membrane. C) nucleoid. D) nucleus. E) ribosomes. - ✔✔nucleoid A major change occu ... rring in the evolution of eukaryotes from prokaryotes was the development of: A) DNA. B) photosynthetic capability. C) plasma membranes. D) ribosomes. E) the nucleus - ✔✔the nucleus In eukaryotes, the nucleus is enclosed by a double membrane called the: A) cell membrane. B) nuclear envelope. C) nucleolus. D) nucleoplasm. E) nucleosome. - ✔✔nuclear envelope The dimensions of living cells are limited, on the lower end by the minimum number of biomolecules necessary for function, and on the upper end by the rate of diffusion of solutes such as oxygen. Except for highly elongated cells, they usually have lengths and diameters in the range of: A) 0.1 µm to 10 µm. B) 0.3 µm to 30 µm. C) 0.3 µm to 100 µm. D) 1 µm to 100 µm. E) 1 µm to 300 µm - ✔✔0.3 µm to 100 µm The bacterium E. coli requires simple organic molecules for growth and energy—it is therefore a: A) chemoautotroph. B) chemoheterotroph. C) lithotroph. D) photoautotroph. E) photoheterotroph - ✔✔chemoheterotroph Which one of the following has the cellular components arranged in order of increasing size? A) Amino acid < protein < mitochondrion < ribosome B) Amino acid < protein < ribosome < mitochondrion C) Amino acid < ribosome < protein < mitochondrion D) Protein < amino acid < mitochondrion < ribosome E) Protein < ribosome < mitochondrion < amino acid - ✔✔Amino acid < protein < ribosome < mitochondrion The three-dimensional structure of macromolecules is formed and maintained primarily through noncovalent interactions. Which one of the following is not considered a noncovalent interaction? A) carbon-carbon bonds B) hydrogen bonds C) hydrophobic interactions D) ionic interactions E) van der Waals interactions - ✔✔carbon-carbon bonds Which one of the following is not among the four most abundant elements in living organisms? A) Carbon B) Hydrogen C) Nitrogen D) Oxygen E) Phosphorus - ✔✔Phosphorus The four covalent bonds in methane (CH4) are arranged around carbon to give which one of the following geometries? A) linear B) tetrahedral C) trigonal bipyramidal D) trigonal planar E) trigonal pyramidal - ✔✔tetrahedral The macromolecules that serve in the storage and transmission of genetic information are: A) carbohydrates. B) lipids. C) membranes. D) nucleic acids. E) proteins - ✔✔nucleic acids Stereoisomers that are nonsuperimposable mirror images of each other are known as: A) anomers. B) cis-trans isomers. C) diastereoisomers. D) enantiomers. E) geometric isomers - ✔✔enantiomers The enzyme fumarase catalyzes the reversible hydration of fumaric acid to l-malate, but it will not catalyze the hydration of maleic acid, the cis isomer of fumaric acid. This is an example of: A) biological activity. B) chiral activity. C) racemization. D) stereoisomerization. E) stereospecificity. - ✔✔stereospecificity Humans maintain a nearly constant level of hemoglobin by continually synthesizing and degrading it. This is an example of a(n): A) dynamic steady state. B) equilibrium state. C) exergonic change. D) free-energy change. E) waste of energy - ✔✔dynamic steady state If heat energy is absorbed by the system during a chemical reaction, the reaction is said to be: A) at equilibrium. B) endergonic. C) endothermic. D) exergonic. E) exothermic - ✔✔endothermic If the free energy change ∆G for a reaction is -46.11 kJ/mol, the reaction is: A) at equilibrium. B) endergonic. C) endothermic. D) exergonic. E) exothermic - ✔✔exergonic The major carrier of chemical energy in all cells is: A) acetyl triphosphate. B) adenosine monophosphate. C) adenosine triphosphate. D) cytosine tetraphosphate. E) uridine diphosphate - ✔✔adenosine triphosphate Enzymes are biological catalysts that enhance the rate of a reaction by: A) decreasing the activation energy. B) decreasing the amount of free energy released. C) increasing the activation energy. D) increasing the amount of free energy released. E) increasing the energy of the transition state - ✔✔decreasing the activation energy Energy requiring metabolic pathways that yield complex molecules from simpler precursors are: A) amphibolic. B) anabolic. C) autotrophic. D) catabolic. E) heterotrophic - ✔✔anabolic Hereditary information (with the exception of some viruses) is preserved in: A) deoxyribonucleic acid. B) membrane structures. C) nuclei. D) polysaccharides. E) ribonucleic acid. - ✔✔deoxyribonucleic acid When a region of DNA must be repaired by removing and replacing some of the nucleotides, what ensures that the new nucleotides are in the correct sequence? A) DNA cannot be repaired and this explains why mutations occur. B) Specific enzymes bind the correct nucleotides. C) The new nucleotides base-pair accurately with those on the complementary strand. D) The repair enzyme recognizes the removed nucleotide and brings in an identical one to replace it. E) The three-dimensional structure de [Show More]

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