Molecular Biology,Molecular Genetics & Microbial-Biochemistry MCQs

--- ### *SECTION A: MULTIPLE CHOICE QUESTIONS (MCQs) (35 MARKS)* *Answer ALL questions.* #### *Question 1* *The larvae of the following helminths enter the human body by penetrating the intact skin:*A. Ancylostoma duodenale and Strongyloides stercoralis B. Trypanosoma brucei gambienseC. Trypanosoma brucei rhodesienseD. Toxoplasma gondii and Plasmodium speciesE. Giardia lamblia and Trichomonas vaginalis *Answer:* *A* (Ancylostoma duodenale and Strongyloides stercoralis) --- #### *Question 2* *Which two protozoa may infect the human fetus transplacentally?*A. Toxoplasma gondii and Plasmodium species B. Giardia lamblia and Trichomonas vaginalisC. Ancylostoma duodenale and Strongyloides stercoralisD. Trypanosoma brucei gambienseE. Trypanosoma brucei rhodesiense *Answer:* *A* (Toxoplasma gondii and Plasmodium species) --- #### *Question 3* *In aerobic respiration, the terminal electron acceptor is:*A. Oxygen B. NitrogenC. HydrogenD. NitrateE. a and b *Answer:* *A* (Oxygen) --- #### *Question 4* *Which of the following are NOT examples of a terminal electron acceptor in anaerobic respiration?*A. NitrateB. Hydrogen sulfideC. Iron hydroxideD. H₂ E. Sulfate *Answer:* *D* (H₂) --- #### *Question 5* *When acetate is the sole source of carbon for some microorganisms, the cycle used is called:*A. Pentose phosphate pathwayB. Glycolytic pathwayC. Glyoxylate pathway D. Oxaloacetate pathwayE. Both C and D *Answer:* *C* (Glyoxylate pathway) --- #### *Question 6* *Most of the energy in aerobic respiration of glucose is captured by:*A. Substrate-level phosphorylationB. Electron transport of electrons from NADH C. Long-chain fatty acid oxidationD. The enzyme formic-hydrogen lyaseE. Both C and D *Answer:* *B* (Electron transport of electrons from NADH) --- #### *Question 7* *The role of bacteriochlorophyll in anoxygenic photosynthesis:*A. Reduce ferredoxin directlyB. Reduce NADP directlyC. Use light energy to energize an electron D. Transfer electrons to an intermediate in the sulfide oxidation pathwayE. A and B *Answer:* *C* (Use light energy to energize an electron) --- #### *Question 8* *Entner-Doudoroff pathway is NOT found in:*A. Aerobic prokaryotesB. Anaerobic prokaryotesC. Both (a) and (b)D. Eukaryotes E. Atypical viral agents *Answer:* *D* (Eukaryotes) --- #### *Question 9* *Which process could result in the net movement of a substance into a cell if the substance is more concentrated in the cell than in the surroundings?*A. Active transport B. DiffusionC. OsmosisD. Facilitated diffusionE. None of the above *Answer:* *A* (Active transport) --- #### *Question 10* *Which is NOT a function of the plasma membrane? The plasma membrane:*A. Has receptors for chemical messagesB. Plays a role in signal transductionC. Is involved in self-recognitionD. Is the control center of the cell E. Forms a selective barrier around the cell *Answer:* *D* (Is the control center of the cell) --- #### *Question 11* *The following substance is used in Gram staining:*A. IodineB. Crystal violet C. AlcoholD. SafraninE. Congo red *Answer:* *B* (Crystal violet) --- #### *Question 12* *This disinfecting agent does NOT act on microbial membrane structures:*A. Cationic detergents (e.g., quaternary ammonium compounds)B. Phenol compounds (e.g., cresol, hexachlorophene)C. ChlorhexidineD. Alcohols (ethanol, isopropanol) E. None of the above *Answer:* *D* (Alcohols) --- #### *Question 13* *The name of the compound shown (pyrimidine base) is:* CLICK TO VIEW A. UracilB. ThymineC. Cytosine D. AdenineE. Guanine *Answer:* *C* (Cytosine) --- #### *Question 14* *What makes the Watson and Crick model of DNA most plausible?*A. It explains DNA structureB. It explains the base ratios in DNAC. It explains how DNA can be packaged in the cellD. It explains DNA structure and its replication E. It won a Nobel prize *Answer:* *D* (It explains DNA structure and its replication) --- #### *Question 15* *A chromosomal aberration where a chromosome arm is lost and replaced by an exact mirror image is called:*A. DuplicationB. TranslocationC. Isochromosome D. InversionE. Deletion *Answer:* *C* (Isochromosome) *The base sequence of the DNA template strand is GATCTAC. What is the RNA product?*A. CTAGATGB. GTAGATCC. GAUCUAC D. GUAGUACE. CUAGAUG *Answer:* *C* (GAUCUAC) --- ### *Question 17* *A mutation where a changed base introduces a stop codon is:*A. Nonsense mutation B. Missense mutationC. Silent mutationD. Deletion mutationE. None of the above *Answer:* *A* (Nonsense mutation) --- ### *Question 18* *What is a tandem repeat?*A. Variation in a single nucleotide positionB. Short DNA sequences repeated in a row, dispersed throughout the genomeC. DNA sequences with varied restriction sitesD. DNA sequences showing length polymorphisms after restrictionE. Short DNA sequences repeated in a row *Answer:* *E* (Short DNA sequences repeated in a row) --- ### *Question 19* *Which does NOT have introns