BCH 3025 EXAM QUESTIONS AND CORRECT ANSWERS VERIFIED 2025

BCH 3025 EXAM QUESTIONS AND CORRECT ANSWERS VERIFIED 2025 In a bacterial cell, the DNA is in the: A) cell envelope. B) cell membrane. C) nucleoid. D) nucleus. E) ribosomes. - ANS-C) nucleoid. A major change occurring in the evolution of eukaryotes from prokaryotes was the development of: A) DNA. B) photosynthetic capability. C) plasma membranes. D) ribosomes. E) the nucleus. - ANS-E) 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. - ANS-B) 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 m to 10 m. B) 0.3 m to 30 m. C) 0.3 m to 100 m. D) 1 m to 100 m. E) 1 m to 300 m. - ANS-C) 0.3 m to 100 m. Which group of single-celled microorganisms has many members found growing in extreme environments? A) Bacteria B) Archaea BCH 3025 BCH 3025 BCH 3025 C) Eukaryotes D) Heterotrophs E) None of the above - ANS-B) Archaea 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. - ANS-B) 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 - ANS-B) 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 - ANS-A) 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 - ANS-E) Phosphorus The four covalent bonds in methane (CH4) are arranged around carbon to give which one of the following geometries? A) Linear BCH 3025 B) Tetrahedral C) Trigonal bipyramidal D) Trigonal planar E) Trigonal pyramidal - ANS-B) Tetrahedral What functional groups are present on this molecule? A) Ether and aldehyde B) Hydroxyl and aldehyde C) Hydroxyl and carboxylic acid D) Hydroxyl and ester E) Hydroxyl and ketone - ANS-B) Hydroxyl and aldehyde The macromolecules that serve in the storage and transmission of genetic information are: A) carbohydrates. B) lipids. C) membranes. D) nucleic acids. E) proteins. - ANS-D) 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. - ANS-D) 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. - ANS-E) 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. BCH 3025 BCH 3025 BCH 3025 B) equilibrium state. C) exergonic change. D) free-energy change. E) waste of energy. - ANS-A) 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. - ANS-C) 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. - ANS-D) 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. - ANS-C) 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. - ANS-A) decreasing the activation energy. Energy requiring metabolic pathways that yield complex molecules from simpler precursors are: A) amphibolic. B) anabolic. C) autotrophic. D) catabolic. BCH 3025 BCH 3025 E) heterotrophic. - ANS-B) 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. - ANS-A) 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 basepair 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 determines the order of nucleotides. - ANS-The new nucleotides basepair accurately with those on the complementary strand. The three-dimensional structure of a protein is determined primarily by: A) electrostatic guidance from nucleic acid structure. B) how many amino acids are in the protein. C) hydrophobic interaction with lipids that provide a folding framework. D) modification during interactions with ribosomes. E) the sequence of amino acids in the protein. - ANS-E) the sequence of amino acids in the protein. According to Oparin's theory for the origin of life, the prebiotic atmosphere: A) already contained some primitive RNA molecules. B) basically was very similar to the atmosphere of today. C) contained many amino acids. D) had an abundance of methane, ammonia, and water. E) was rich in oxygen. - ANS-D) had an abundance of methane, ammonia, and water. To possess optical activity, a compound must be: A) a carbohydrate. B) a hexose. C) asymmetric. D) colored. E) D-glucose. - ANS-C BCH 3025 Which of the following monosaccharides is not an aldose? A) erythrose B) fructose C) glucose D) glyceraldehyde E) ribose - ANS-B The reference compound for naming D and L isomers of sugars is: A) fructose. B) glucose. C) glyceraldehyde. D) ribose. E) sucrose. - ANS-C When two carbohydrates are epimers: A) one is a pyranose, the other a furanose. B) one is an aldose, the other a ketose. C) they differ in length by one carbon. D) they differ only in the configuration around one carbon atom. E) they rotate plane-polarized light in the same direction. - ANS-D Which of the following is an epimeric pair? A) D-glucose and D-glucosamine B) D-glucose and D-mannose C) D-glucose and L-glucose D) D-lactose and D-sucrose E) L-mannose and L-fructose - ANS-B Which of following is an anomeric pair? A) D-glucose and D-fructose B) D-glucose and L-fructose C) D-glucose and L-glucose D) alpha-D-glucose and beta-D-glucose E) alpha-D-glucose and beta-L-glucose - ANS-D When the linear form of glucose cyclizes, the product is a(n): A) anhydride. B) glycoside. C) hemiacetal. D) lactone. BCH 3025 BCH 3025 E) oligosaccharide. - ANS-C Which of the following pairs is interconverted in the process of mutarotation? A) D-glucose and D-fructose B) D-glucose and D-galactose C) D-glucose and D-glucosamine D) D-glucose and L-glucose E) alpha-D-glucose and beta-D-glucose - ANS-E Which of the following is not a reducing sugar? A) Fructose B) Glucose C) Glyceraldehyde D) Ribose E) Sucrose - ANS-E Which of the following monosaccharides is not a carboxylic acid? A) 6-phospho-gluconate B) gluconate C) glucose D) glucuronate E) muramic acid - ANS-C D-Glucose is called a reducing sugar because it undergoes an oxidation-reduction reaction at the anomeric carbon. One of the products of this reaction is: A) D-galactose. B) D-gluconate. C) D-glucuronate. D) D-ribose. E) muramic acid. - ANS-B Hemoglobin glycation is a process where is attached to hemoglobin. A) glycerol; covalently B) glucose; enzymatically C) glucose; non-enzymatically D) N-acetyl-galactosamine; enzymatically E) galactose; non-enzymatically - ANS-C From the abbreviated name of the compound Gal(1 4)Glc, we know that: A) C-4 of glucose is joined to C-1 of galactose by a glycosidic bond. BCH 3025 BCH 3025 B) the compound is a D-enantiomer. C) the galactose residue is at the reducing end. D) the glucose is in its pyranose form. E) the glucose residue is the beta anomer. - ANS-A Starch and glycogen are both polymers of: A) fructose. B) glucose1-phosphate. C) sucrose. D) alpha-D-glucose. E) beta-D-glucose. - ANS-D Which of the following statements about starch and glycogen is false? A) Amylose is unbranched; amylopectin and glycogen contain many (alpha1→ 6) branches. B) Both are homopolymers of glucose. C) Both serve primarily as structural elements in cell walls. D) Both starch and glycogen are stored intracellularly as insoluble granules. E) Glycogen is more extensively branched than starch. - ANS-C Which of the following is a heteropolysaccharide? A) Cellulose B) Chitin C) Glycogen D) Hyaluronate E) Starch - ANS-D The basic structure of a proteoglycan consists of a core protein and a: A) glycolipid. B) glycosaminoglycan. C) lectin. D) lipopolysaccharide. E) peptidoglycan. - ANS-B In glycoproteins, the carbohydrate moiety is always attached through the amino acid residues: A) asparagine, serine, or threonine. B) aspartate or glutamate. C) glutamine or arginine. D) glycine, alanine, or aspartate. E) tryptophan, aspartate, or cysteine. - AN