This biology question covers important biological concepts and processes. The step-by-step explanation below helps you understand the underlying mechanisms and reasoning.
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here are the answers to the parasitology questions: SECTION B 1. A bladder containing an attached single invaginated scolex is called a cysticercus. 2. The expansion of blood vessels which could be due to parasitic activities is called vasodilation. 3. An organism that may live free living, but could also obtain nutrition from a host is called a facultative parasite. 4. An organism in which the parasite reaches the adult stage and reproduces sexually, is called a definitive host. 5. An organism in which the parasite reaches the adult stage and reproduces sexually, is called a definitive host. 6. The chain of segments which constitute a cestode is known as strobila. 7. An example of nematodes in the large intestine is _Oesophagostomum_ species (e.g., nodular worm) or _Strongylus_ species (in horses). 8. Mange is an example of mite Arachnid. 9. The parasite causing malaria in monkey is called _Plasmodium knowlesi_. 10. Coccidia belongs to the family Eimeriidae (or suborder Eimeriorina). SECTION C Question One a. Cestode infestation in sheep: i. Explain the possible means by which the cestodes were transmitted to these animals. Cestodes are typically transmitted to sheep through the ingestion of an intermediate host that harbors the infective larval stage of the parasite. For many common sheep cestodes (e.g., Moniezia species), the intermediate host is a pasture mite (oribatid mite) which ingests the cestode eggs. Sheep become infected by grazing on pastures contaminated with these infected mites. ii. What kind of life cycle do these cestodes have? These cestodes have an indirect life cycle, meaning they require at least one intermediate host (e.g., pasture mite) to complete their development and transmission to the definitive host (sheep). iii. What stage of the life cycle of these cestodes would you describe as infective? The infective stage for the sheep (definitive host) is the cysticercoid (larval stage) found within the intermediate host (pasture mite). iv. Give two (2) forms or types of larval stages in which an egg of these cestodes could develop into. Two forms of larval stages that an egg of cestodes could develop into are: • Cysticercoid: A small, solid larval stage found in invertebrate intermediate hosts (e.g., Moniezia in mites). • Cysticercus: A bladder-like larval stage containing a single invaginated scolex, typically found in vertebrate intermediate hosts (e.g., Taenia ovis in sheep muscle). b. Discuss five (5) factors that are common to both Plasmodium knowlesi and Leishmania species. Here are five common factors: • Vector-borne Transmission: Both Plasmodium knowlesi and Leishmania species are transmitted to their mammalian hosts through the bite of an arthropod vector. Plasmodium knowlesi is transmitted by Anopheles mosquitoes, while Leishmania species are transmitted by sandflies. • Intracellular Parasitism: Both parasites are obligate intracellular parasites during at least part of their life cycle in the mammalian host. Plasmodium knowlesi infects red blood cells and liver cells, while Leishmania species infect macrophages. • Zoonotic Potential: Both can cause zoonotic diseases, meaning they can be transmitted from animals to humans. Plasmodium knowlesi is primarily a parasite of macaques but can cause malaria in humans. Leishmania species have various animal reservoirs (e.g., rodents, dogs) that can transmit the disease to humans. • Complex Life Cycles: Both parasites exhibit complex life cycles involving multiple developmental stages and hosts (definitive and intermediate/vector). • Geographical Distribution: Both diseases are prevalent in tropical and subtropical regions, often overlapping in areas where their respective vectors and hosts are found. Question Two a. Match the terms in A with those in B: • Trypanosoma: anterior trypomastigote (a specific morphological stage) • Coccidia: oocysts (the resistant, infective stage shed in feces) • Trematodes: miracidia (the ciliated larval stage that infects the first intermediate host, usually a snail) • Cestodes: proglottids (segments of the strobila containing reproductive organs) • Nematodes: dioecious (having separate male and female individuals) i. What is common to all of them? All of them are parasites. ii. Name one host each that can be infected by these parasites. • Trypanosoma: Human (e.g., Trypanosoma brucei causing sleeping sickness) • Coccidia: Chicken (e.g., Eimeria tenella causing coccidiosis) • Trematodes: Snail (as a first intermediate host for many species) • Cestodes: Dog (e.g., Taenia hydatigena) • Nematodes: Sheep (e.g., Haemonchus contortus) b. Give one (1) example each of cestodes affecting dog and cattle. • Cestode affecting dog: _Dipylidium caninum_ (flea tapeworm) or _Taenia hydatigena_. • Cestode affecting cattle: _Moniezia expansa_ (ruminant tapeworm) or _Taenia saginata_ (larval stage, Cysticercus bovis, in cattle). What's next? Send 'em! 📸