Medical Bacteriology and Entomology Exam OmpathStudy

Medical Bacteriology and Entomology Exam 2020/2021 --- SECTION A: Answer ALL Questions (35 marks) Question 1 Which of the following is the odd one out in terms of its mode of transmission? A) Vibrio cholerae B) Entamoeba histolytica C) Rotavirus D) Thelazia species E) None of the above Answer: D) Thelazia species Explanation: 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. --- Question 2 Which one of the following is larviparous? A) Phlebotomus species B) Lutzomyia species C) Triatomine bugs D) Glossina species E) Dermacentor species Answer: D) Glossina species Explanation: 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. --- Question 3 Argasid ticks have: A) One host B) Two hosts C) Three hosts D) Four hosts E) Multiple hosts Answer: E) Multiple hosts Explanation: 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. --- Question 4 Ixodid ticks have how many nymphal stages? A) One B) Two C) Three D) Four E) Multiple Answer: A) One Explanation: Ixodid (hard) ticks have a single nymphal stage in their life cycle: egg → larva → nymph → adult. --- Question 5 Traps for Aedes mosquitoes are composed of: A) Black and white colors B) Black and blue colors C) White and blue colors D) White only E) Black only Answer: A) Black and white colors Explanation: 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. --- Question 6 Traps for Glossina species are composed of: A) Black and white colors B) Black and blue colors C) White and blue colors D) Blue only E) Black only Answer: B) Black and blue colors Explanation: 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. --- Question 7 Blackwater fever is due to presence of which species in the environment? A) Simulium species B) Anopheles species C) Culicoides species D) Lutzomyia species E) Musca species Answer: B) Anopheles species Explanation: 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. --- Question 8 Hepatitis B virus has been associated with: A) Cimex species B) Xenopsylla species C) Pthirus species D) Tabanids species E) Glossina species Answer: A) Cimex species Explanation: 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. --- Question 9 Snails are both first and second intermediate hosts of: A) Echinostoma ilocanum B) Fasciola hepatica C) Fasciolopsis buski D) Hymenolepis nana E) Paragonimus westermanii Answer: A) Echinostoma ilocanum Explanation: Echinostoma ilocanum uses snails as both first and second intermediate hosts in its complex life cycle, unlike other flukes that use different intermediate hosts. --- Question 10 How can millipedes cause medical problems? A) Stinging B) Spraying defensive secretions C) Transmitting viruses D) Laying eggs under skin E) None of the above Answer: B) Spraying defensive secretions Explanation: Millipedes defend themselves by secreting toxic chemicals (hydrogen cyanide, quinones) that can cause skin irritation, burns, and eye damage in humans. --- Question 11 Holometabolous insects have: A) 2 life stages B) 3 life stages C) 4 life stages D) 1 life stage E) None of the above Answer: C) 4 life stages Explanation: Holometabolous insects undergo complete metamorphosis with four distinct stages: egg, larva, pupa, and adult. Examples include flies, beetles, and butterflies. --- Question 12 Rift Valley fever is mainly transmitted by: A) Culex species B) Aedes species C) Anopheles species D) Toxorhynchites species E) None of the above Answer: B) Aedes species Explanation: Rift Valley fever virus is primarily transmitted by Aedes mosquitoes, particularly Aedes mcintoshi and Aedes ochraceus in flood-water breeding sites. --- Question 13 Autogenous insects: A) Lay eggs without mating B) Mate but do not lay eggs C) Are blood seekers D) Are sugar feeders E) None of the above Answer: A) Lay eggs without mating Explanation: 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. --- Question 14 Parthenogenesis is a type of: A) Asexual re