🦠 Microbiology Solved MCQs with Answers

Practice 1927 approved 🦠 Microbiology questions with verified answers from the 🧬 Medical Science subject for Pakistan exams.

1927 solved MCQs

To a living organism, which of the following has the greatest amount of available energy per molecule?Answer: ATP Which of the following is the best evidence for the lock and key theory of enzyme action?Answer: Compounds similar in structure to the substrate inhibit enzyme activity The fact that β-oxidation of fatty acids, occurs in the mitochondria whereas fatty acid synthesis occurs in the cytoplasmic matrix, is an example of regulation of enzymatic activity by the __________ mechanism.Answer: repression The affinity of an enzyme for its substrate, when the enzyme has a Km of 0.50 M will be __________ than the affinity of an enzyme for its substrate when the enzyme has a Km of 0.05 M.Answer: lesser Anthranilate synthase, the first enzyme of tryptophan biosynthesis after the branch point shows feedback inhibition and repression due toAnswer: L-tryptophan A substrate binds to its enzyme at a location called the __________ site.Answer: active Hydrogen and oxygen release enormous amounts of energy when they react. Yet, hydrogen and oxygen can be mixed together in a balloon and nothing will happen. Why?Answer: Competitive inhibitors are blocking the reaction from occurring in the active site Adenosine triphosphate is a type ofAnswer: nucleotide An enzyme that is always produced, regardless of the presence of substrates or the end products, is calledAnswer: a constitutive enzyme The ability of CTP to bind to aspartate carbamoyltransferase and shut down the synthesis of more CTP is an example ofAnswer: feedback inhibition of enzyme activity Oxidation is theAnswer: loss of electron Denaturation of an enzyme refers to theAnswer: loss of the enzymes proper shape About 7.3 kcal/mole are released whenAnswer: Glucose is converted to CO₂ and H₂O In the reaction,C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O+ energy, which component is being oxidized?Answer: C₆H₁₂O₆ During the carboxylation phase of the Calvin cycle, CO₂ combines withAnswer: ribulose 1,5 - bisphosphate In the passive diffusion, solute molecules cross the membrane as a result ofAnswer: concentration difference In an oxygenic photosynthesis, the green and the purple bacteria do not use which of the following one as an electron source?Answer: H₂O Radioisotopes are frequently used in the study of cells. Assume a culture of E. coli is grown in a culture medium containing radioactive phosphorous. At the end of 48 hours, it is expected to find the radioactive label located inAnswer: all of these Assimilatory sulfate reduction involves the nucleotide __________ during the incorporation of H₂S in the production of __________ .Answer: ATP; cytosine The chlorophyll molecules used by eucaryotes and cyanobacteria absorb radiant energy in the____________portion(s) of the visible spectrum.Answer: red and blue In aerobic respiration, the terminal electron acceptor isAnswer: oxygen Which of the following statement is correct?Answer: Phosphate repression can not be eliminated by optimization of nutrient medium, deregulated medium must be used as production strains The acquisition energy by glucose fermentation requiresAnswer: substrate-level phosphorylation High energy transfer compounds are capable ofAnswer: transferring large amounts of free energy Dolichol phosphate isAnswer: the anchor on which sugars assemble before transfer to proteins The reactions of the cell that are carried out for capturing energy are calledAnswer: catabolism In establishing proton gradient for chemiosmotic ATP generation by aerobic respiration the terminal electron acceptor isAnswer: oxygen If ΔG of a chemical reaction is positive in value and Kₑq is less than 1 then the chemical reaction willAnswer: proceed in reverse direction The reaction, where small precursor molecules are assembled into larger organic molecules is referred asAnswer: anabolism Which of the following nucleoside diphosphates is used most often in carbohydrate anabolism?Answer: Uridine diphosphate