BACHELOR OF MEDICINE AND BACHELOR OF SURGERY (MBChB) DEGREE UNIT CODE: MDBS 3101 UNIT TITLE: Parasitology / Entomology / Bacteriology YEAR 3, PAPER 1 DATE: 3rd
BACHELOR OF MEDICINE AND BACHELOR OF SURGERY (MBChB) DEGREE UNIT CODE: MDBS 3101 UNIT TITLE: Parasitology / Entomology / Bacteriology YEAR 3, PAPER 1 DATE: 3rd July, 2018 – 8.00 a.m. TIME: 3 Hours --- INSTRUCTIONS: - Answer all questions in Sections A and B. - Answer any two (2) questions in Section C. - SECTION A: MULTIPLE CHOICE QUESTIONS Question 1 What kinds of roaches might you expect to encounter in Athens? A) German roaches B) American roaches C) Smokey brown roaches D) All of the above E) None of the above Answer: D) All of the above Explanation: Athens, with its Mediterranean climate and urban environment, supports multiple cockroach species including German roaches (most common indoor species), American roaches (prefer warm, moist areas), and Smokey brown roaches (outdoor species that enter buildings). --- Question 2 What is the main advantage of using larval control against mosquitoes? A) Control will supplement natural control B) Larvae are restricted to confined aquatic habitats that can be treated C) Larval habitats do not support sensitive other organisms D) All of the above E) None of the above Answer: B) Larvae are restricted to confined aquatic habitats that can be treated Explanation: Larval control is advantageous because mosquito larvae are confined to specific aquatic breeding sites (pools, containers, marshes) making them easier to target with larvicides or environmental management compared to flying adult mosquitoes that are widely dispersed. --- Question 2 If you found lice eggs (nits) in someone's clothing, what species would they most likely be from? A) Crab lice (Pthirus pubis) B) Head lice (Pediculus capitis) C) Body lice (Pediculus humanus) D) Hog lice E) All of the above Answer: C) Body lice (Pediculus humanus) Explanation: Body lice (Pediculus humanus corporis) are the only lice species that lay their eggs (nits) on clothing fibers, particularly along seams of garments. Head lice attach nits to hair shafts, while crab lice attach to coarse body hair. --- Question 3 What are effective non-pesticide ways to control problems from cockroaches? A) Store food in plastic containers B) Clean your kitchen counter tops nightly C) Seal up cracks and seams around pipes and cabinets D) All of the above E) A and C Answer: D) All of the above Explanation: Integrated pest management for cockroaches includes removing food sources (sealed containers), eliminating food residues (cleaning), and blocking entry points (sealing cracks). All these methods work together to make environments less suitable for cockroach survival and reproduction. --- Question 4 The pupal stage is found in: A) Incomplete metamorphosis B) Complete metamorphosis C) Both incomplete and complete metamorphosis D) Neither incomplete nor complete metamorphosis E) None of the above Answer: B) Complete metamorphosis Explanation: The pupal stage only occurs in complete metamorphosis (holometabolism) where insects go through egg → larva → pupa → adult stages. Incomplete metamorphosis (hemimetabolism) has only egg → nymph → adult stages with no pupal stage. --- Question 6 How does insecticide resistance develop? A) By using Integrated Pest Management practices B) By using low doses of insecticides C) By using high or prolonged doses of insecticide D) B and C E) None of the above Answer: D) B and C Explanation: Insecticide resistance develops through both low doses (sub-lethal doses allow resistant individuals to survive and reproduce) and high/prolonged doses (intense selection pressure favors resistant genotypes). IPM actually helps prevent resistance by reducing selection pressure. --- Question 8 Ceratopogonidae larvae are found in: A) Freshwater marshes B) Salt marshes C) Wet muddy areas around cattle watering tanks D) All of the above E) A and B Answer: D) All of the above Explanation: Ceratopogonidae (biting midges/no-see-ums) larvae are semi-aquatic and found in various moist environments including freshwater marshes, salt marshes, and muddy areas around water sources. Different species adapt to different salinity and moisture conditions. --- Question 9 Integrated Pest Management: A) Relies solely on pesticides B) Relies solely on biological and natural control C) Considers the biology of the target pest D) A and B E) All of the above Answer: C) Considers the biology of the target pest Explanation: IPM is a comprehensive approach that considers pest biology, ecology, and behavior to develop sustainable control strategies. It integrates multiple control methods (biological, cultural, chemical, mechanical) rather than relying solely on any single approach. --- Question 11 Epidemic typhus and Chagas disease can both be vectored via: A) Saliva of a vector B) Feces (frass) of a vector C) Mosquitoes D) Cockroaches E) A and B Answer: B) Feces (frass) of a vector Explanation: Both epidemic typhus (Rickettsia prowazekii via body lice) and Chagas disease (Trypanosoma cruzi via triatomine bugs) are transmitted through contaminated vector feces rubbed into bite wounds or mucous membranes, not through vector saliva. --- Question 12 Which of the following groups of Glossina species is insignificant in the transmission of Trypanosoma brucei rhodesiense? A) Palpalis group B) Morsitans group C) Fusca group D) None of the above E) All of the above Answer: A) Palpalis group Explanation: The Palpalis group of tsetse flies primarily transmits T. b. gambiense (West African sleeping sickness), while the Morsitans and Fusca groups are the main vectors for T. b. rhodesiense (East African sleeping sickness). --- Question 13 Which of these habitats would be likely places for mosquito larvae to live? A) Clogged drainage ditch B) Fast flowing stream C) Lake or reservoir D) A and B E) All of the above Answer: E) All of the above Explanation: Different mosquito species have adapted to various aquatic habitats. Culex breeds in polluted water (drainage ditches), some Anopheles species in clean flowing water, and many species utilize large water bodies like lakes and reservoirs for breeding. --- Question 14 Which of the above does NOT attract host seeking mosquitoes? A) Carbon dioxide B) Host odors C) The color white D) A and C E) All of these attract mosquitoes Answer: C) The color white Explanation: Mosquitoes are attracted to CO₂ and host odors (lactic acid, ammonia, etc.) but are generally repelled by light colors like white. They are more attracted to dark colors (black, navy, red) which retain heat and provide visual contrast. --- Question 15 Glossina species are easily controlled by traps impregnated with which colors? A) Red and blue B) Red and white C) Blue and black D) Black and white E) Any of the above Answer: C) Blue and black Explanation: Tsetse flies are strongly attracted to blue and black colors. This attraction is exploited in tsetse control programs using blue-black cloth traps or targets, often impregnated with insecticides for effective population control. --- Question 16 Which of the following organisms have the characteristics to be an effective mechanical vector of human disease? A) Simulium B) Culicine C) Blattella D) All of the above E) None of the above Answer: D) All of the above Explanation: All can serve as mechanical vectors: Simulium (blackflies) can carry pathogens on mouthparts, Culicine mosquitoes can mechanically transfer pathogens between hosts, and Blattella (cockroaches) carry pathogens on their bodies and legs from contaminated areas to food/surfaces. --- Question 17 Where might you look if you suspected bedbugs have infested your house? A) Behind the headboard of the bed B) Between the mattress and the box spring C) In cavities in the bed frame D) A and B E) All of the above Answer: E) All of the above Explanation: Bedbugs hide in cracks and crevices near sleeping areas during the day. Common hiding places include behind headboards, mattress seams, box spring crevices, bed frame joints, and other furniture cracks within 8 feet of the bed. --- Question 19 Which