--- SECTION A: MULTIPLE CHOICE QUESTIONS (MCQs) (35 MARKS) Answer ALL questions. Question 1 The larvae of the following helminths enter the human body by penetr
--- 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? A. DNAB. mRNA transcriptC. mRNAD. tRNA E. miRNA Answer: D (tRNA) --- Question 20 The following conditions are caused by recessive genetic defects. Which one is NOT? A. AlbinismB. Neurofibromatosis C. GalactosemiaD. Tay-Sachs diseaseE. Duchenne Muscular Dystrophy Answer: B (Neurofibromatosis) --- Question 21 If the molar amount of T in DNA is 30%, what is the molar amount of C? A. 20% B. 30%C. 40%D. 60%E. 50% Answer: A (20%) --- Question 22 Why is a sex-linked trait likely passed to male grandchildren from the grandfather through his female offspring? A. Daughters inherit two X chromosomes from their fatherB. Male child inherits one X chromosome from their mother C. Male child inherits one X chromosome with the defective trait from his grandfatherD. Males are prone to inherit defective characters due to their Y chromosomeE. Males inherit only one X chromosome Answer: B (Male child inherits one X chromosome from their mother) --- Question 23 Which statement is NOT true? A. DNA replication occurs in the nucleusB. DNA replication begins at the replication forkC. DNA replication is catalyzed by DNA polymeraseD. DNA replication occurs prior to cell divisionE. DNA replication is catalyzed by RNA polymerase Answer: E (DNA replication is catalyzed by RNA polymerase) --- Question 24 Which enzyme is NOT involved in replication? A. DNA polymeraseB. RNA polymerase C. LigaseD. HelicaseE. Primase Answer: B (RNA polymerase) --- Question 25 Which process requires an RNA primer? A. TranscriptionB. TranslationC. Replication D. PCRE. C and D Answer: C (Replication) --- Question 26 In eukaryotes, transcription and translation occur in: A. Both occur in the cytosolB. Cytosol and nucleus respectivelyC. Ribosome and nucleus respectivelyD. Nucleus and cytosol respectively E. Nucleus and ribosome respectively Answer: D (Nucleus and cytosol respectively) --- Question 27 The function of tRNA is to: A. Transfer an amino acid to the ribosome from the cytosolB. Carry an amino acid from the cytosol to the ribosome C. Carry an amino acid from the ribosome to the cytosolD. Transfer an amino acid from the ribosome to the cytosolE. A and B Answer: B (Carry an amino acid from the cytosol to the ribosome) --- Question 28 Which is true about Xeroderma pigmentosum? A. It occurs due to a missense mutationB. It occurs due to a frameshift mutationC. It increases kidney cancer riskD. It is not inheritedE. It leads to reduced ability to repair UV-induced DNA damage Answer: E (It leads to reduced ability to repair UV-induced DNA damage) --- Question 29 Which is important in maintaining DNA replication fidelity? A. DNA polymerase 3'–5' proofreading B. RNA polymerase 3'–5' proofreadingC. Thymine dimer exonucleaseD. NoneE. B and C Answer: A (DNA polymerase 3'–5' proofreading) --- Question 30 Which is NOT a type of mutation? A. SubstitutionB. FrameshiftC. Macro lesionsD. Micro lesionsE. Multiple lesions Answer: E (Multiple lesions) --- Question 31 PCR is catalyzed by: A. DNA polymeraseB. RNA polymeraseC. Taq DNA polymerase D. Taq RNA polymeraseE. Topoisomerases Answer: C (Taq DNA polymerase) --- Question 32 Which is true about recombinant DNA technology? A. It is important for the synthesis of DNAB. It involves the combination of a target DNA to a host DNA C. It occurs naturally in higher organismsD. It i