39 Year 2: Parasitology exam questions on Medical Bacteriology and Entomology Exam 2020/2021 for medical students. Includes MCQs, answers, explanations and writ
This MCQ set contains 39 questions on Medical Bacteriology and Entomology Exam 2020/2021 in the Year 2: Parasitology unit. Each question includes the correct answer and a detailed explanation for active recall and exam preparation.
Correct answer: D – Thelazia species
Vibrio cholerae , Entamoeba histolytica , and Rotavirus are all transmitted through the fecal-oral route (contaminated water/food). Thelazia species (eyeworms) are transmitted by flies that feed on lacrimal secretions, making it the odd one out.
Correct answer: D – Glossina species
Larviparous insects give birth to live larvae rather than laying eggs. Tsetse flies ( Glossina species) are larviparous, producing one larva at a time that pupates immediately after birth.
Correct answer: E – Multiple hosts
Argasid (soft) ticks are multi-host ticks that can feed on different hosts throughout their life cycle and can take multiple blood meals at each life stage.
Correct answer: A – One
Ixodid (hard) ticks have a single nymphal stage in their life cycle: egg → larva → nymph → adult.
Correct answer: A – Black and white colors
Aedes mosquitoes are attracted to contrasting black and white patterns. Ovitrap designs often use black containers with white interiors or black and white striped patterns.
Correct answer: B – Black and blue colors
Tsetse flies ( Glossina species) are attracted to blue and black colors. Standard tsetse traps use blue cloth with black panels to attract the flies effectively.
Correct answer: B – Anopheles species
Blackwater fever is a severe complication of falciparum malaria characterized by massive hemolysis and dark urine. It's associated with Plasmodium falciparum infection transmitted by Anopheles mosquitoes.
Correct answer: A – Cimex species
While not definitively proven, bed bugs ( Cimex species) have been investigated as potential mechanical vectors for Hepatitis B virus, though human-to-human transmission remains the primary route.
Correct answer: A – Echinostoma ilocanum
Echinostoma ilocanum uses snails as both first and second intermediate hosts in its complex life cycle, unlike other flukes that use different intermediate hosts.
Correct answer: B – Spraying defensive secretions
Millipedes defend themselves by secreting toxic chemicals (hydrogen cyanide, quinones) that can cause skin irritation, burns, and eye damage in humans.
Correct answer: C – 4 life stages
Holometabolous insects undergo complete metamorphosis with four distinct stages: egg, larva, pupa, and adult. Examples include flies, beetles, and butterflies.
Correct answer: B – Aedes species
Rift Valley fever virus is primarily transmitted by Aedes mosquitoes, particularly Aedes mcintoshi and Aedes ochraceus in flood-water breeding sites.
Correct answer: A – Lay eggs without mating
Autogenous insects can develop their first batch of eggs without taking a blood meal, using nutrient reserves from their larval stage. This is different from anautogenous insects that require blood meals.
Correct answer: A – Asexual reproduction in which offspring develops from unfertilized egg
Parthenogenesis is a form of asexual reproduction where offspring develop from unfertilized eggs, essentially creating genetic clones of the parent.
Correct answer: A – Cockroaches
Order Blattaria (now called Blattodea) includes cockroaches and termites. Lice belong to Phthiraptera, flies to Diptera, and beetles to Coleoptera.
Correct answer: D – Integrated vector management
Integrated vector management combines multiple control strategies (bed nets, treatment, environmental management, etc.) and is considered the most effective approach for sustainable malaria control.
Correct answer: A – Mixed normal gastrointestinal flora
Diverticular abscesses typically contain mixed anaerobic and aerobic bacteria from normal colonic flora, including Bacteroides , E. coli , Enterococcus , and other enteric bacteria.
Correct answer: D – Clostridium difficile
C. difficile is relatively resistant to many antibiotics and can overgrow when normal flora is suppressed. It produces toxins A and B that cause antibiotic-associated colitis.
Correct answer: E – Group B streptococci
Streptococcus agalactiae (Group B Strep) is normal vaginal flora in ~25% of women but can cause serious infections in newborns, including meningitis, pneumonia, and sepsis.
Correct answer: A – Biofilm formation
Dental plaque is a classic example of biofilm formation where bacteria adhere to tooth surfaces and produce extracellular matrix, leading to periodontal disease.
Correct answer: B – Streptococcus mutans
S. mutans is the primary causative agent of dental caries. It produces acids from sugar metabolism that demineralize tooth enamel and produces sticky glucans that help it adhere to teeth.
Correct answer: B – Nasopharynx
S. pneumoniae commonly colonizes the nasopharynx asymptomatically. Colonization rates are highest in children and can lead to invasive disease under certain conditions.
Correct answer: B – Urethra
The distal urethra contains resident flora, primarily Staphylococcus epidermidis and other coagulase-negative staphylococci. The other sites listed are normally sterile.
Correct answer: D – Synovial fluid
Synovial fluid in healthy joints is sterile. The other sites normally contain resident flora, though the lungs have minimal flora in healthy individuals.
Correct answer: D – Candida albicans
The description of ovoid organisms reproducing by budding describes yeast. Candida albicans commonly causes catheter-related bloodstream infections, especially in patients on broad-spectrum antibiotics.