Bio-chemistry Test bank (All 23 chapters complete, Questions and Answers)

1) Which elements account for more than 97% of the weight of most organisms? A) C, H, N, Mg, O, S B) C, H, N, O, P, S C) C, H, N D) Fe, C, H, O, P E) Ca2+, K+, Na+, Mg2+, ClAnswer: B Page Ref: Section 2 2) Proteins in biological membranes may be A) porous. B) attached to the membrane surface. C) span the membrane. D) All of the above E) B and C only Answer: D Page Ref: Section 3 3) Which statement about cellulose is false? A) It is the most abundant polysaccharide in nature. B) Its monomers are joined by glycosidic bonds. C) It is present in the stems of flowering plants. D) The hydroxyl groups of neighboring cellulose molecules interact to form strong, insoluble fibers. E) It is a branched polymer of glucose. Answer: E Page Ref: Section 3 1 4) When Keq of a reaction = 1, then A) the forward reaction is faster than the reverse reaction. B) the reverse reaction is faster than the forward reaction. C) the forward and reverse reaction rate constants are equal. D) more products are formed than reactants. E) fewer products are formed than reactants. Answer: C Page Ref: Section 4 5) Which statement is true about a reaction with an equilibrium constant, Keq, equal to 1000? A) The forward rate constant is 1000 times greater than the reverse rate constant. B) The forward rate constant is 3 times greater than reverse rate constant. C) The forward rate constant is 1000 times smaller than the reverse rate constant. D) The forward rate constant is 3 times smallerthan the reverse rate constant. E) There is not enough information given to compare the forward and reverse rate constants. Answer: A Page Ref: Section 4 6) The study of the energy changes during metabolic reactions is called ________. A) bioinformatics B) metabodynamics C) thermometrics D) bioenergetics E) biological heat dynamics Answer: D Page Ref: Section 4 7) A spontaneous chemical reaction always has a ________ change. A) positive Gibbʹs free energy B) negative Gibbʹs free energy C) positive enthalpy D) negative enthalpy E) positive entropy Answer: B Page Ref: Section 4 2 8) Prokaryotes are valuable tools for biochemists because A) E. coli is well-studied and typical of prokaryotes. B) they contain as many genes as eukaryotic cells. C) many of their chromosomes are sequenced. D) they are not very diverse organisms. E) All of the above Answer: C Page Ref: Section 6 9) Which cellular component carries out oxidation reactions, some of which produce hydrogen peroxide? A) peroxisomes B) mitochondria C) chloroplasts D) lysosomes E) vacuoles Answer: A Page Ref: Section 8 10) Why is it important that the enzymes in lysosomes are more active at acidic pH than at neutral pH? A) Since lysosomes are primarily found in the stomach acid of mammals, their pH dependence allows for maximum efficiency for the digestion of foodstuffs. B) It prevents their diffusion out of the lysosomes. C) It maximizes the interaction with their substrates which are always bases. D) It prevents them from accidentally degrading the macromolecules in the cytosol. E) It allows for regulation of their uptake by the mitochondria. Answer: D Page Ref: Section 8