Final exam: plants and invertebrates Flashcards
Define what it means by intermediate host and definitive host in an endoparasite lifecycle.
Intermediate host: organisms that harbour larval/immature stages of parasites until they move onto the final host.
Definitive host: The final host harbours a parasite through its adult life until it completes its lifecycle.
What are the 3 essential processes of a parasitic lifecycle?
- getting on/into their host
- Establishment (protect themselves from a host defence mechanism)
- Disperal (moving from one host to the next)
Name a parasite of the class CESTODA (tapeworms)
Echinococcus granulosus.
What is the phylum, class and order of tapeworms?
Phylum: Platyhelminthes
Class: Cestoda
Order: Cyclophyllidea
Give an example of an endoparasite from class cestoda and define key stages of its lifecycle.
Echinococcus granulosus (tapeworm)
Most commonly infects canidae (dogs).
- Eggs enter host via ingesting fecal matter containing eggs
- eggs enter intermediate host (cattle) and hatch into free swimming larvae (oncsopshere)
- oncosphere becomes invaginated encysted stage (cysticercus / bladder worm)
- mature worm develops once invaginated cysticercus is eaten by definitive host (canidae)
How does the chosen tapeworm evade host defence?
induce host t-helper2 cell response leading to limitation of anti-parasitic immune response.
germinal layer of the cyst provides a barrier against immune responses.
What is the definitive host for Echinococcus granulosus?
The hydatid worm commonly infects Dogs//Canidae as its definitive host. Rarely humans.
What is the intermediate host for Echinococcus granulosus?
Hydatid worm commonly uses cattle as its intermediate host during larval stages.
Name a parasite of the class TREMATODE (Flatworms)
Fasciola hepatica (flukes)
What is the phylum, class and order of flatworms?
Phylum: Platyhelminthes
Class: Trematoda
Order: ?
Give an example of an endoparasite from class trematoda and define key stages of its lifecycle.
- Embryonated eggs passed via feces into water
- Larvae released in water and penetrate snail
- Larvae go through several stages developing into an immature form of the fluke (cercariae)
- cercariae released from snail and form cysts on water plants (watercress)
- Definitive host eat contaiminated cystic waterplants
- cysts release larvae and penetrate intestinal wall to liver (bile ducts)
- adult flukes develop and release eggs
How does the chosen flatworm evade host defence?
Fasciola hepatica:
Down regulates host immune response via excretory/secretory products during early development.
What is the definitive host for Fasciola hepatica?
Definitive host for flatworms is generally humans or cattle that ingest contaminated waterplants.
What is the intermediate host for Fasciola hepatica?
Intermediate host is a snail where larval development occurs into cercariae, which is then released from snail.
Name a parasite of the class NEMATODE (Roundworms)
Ascaris lumbricoides
What is the phylum, class and order of roundworms?
Phylum: Nematode
Class: Ascarididae
Order: ?
Give an example of an endoparasite from class Nematoda and define key stages of its lifecycle.
Ascaris lumbricoides
1. Oral-fecal infections
- Eggs in feces develop in the environment and are swallowed from contaminated ingestibles.
- eggs hatch in the intestine
- Larvae migrate to lungs
- Larvae coughed up and swallowed
- Adults develop in intestine
How many hosts does a nematode have?
One!
How does the chosen roundworm evade host defence?
produces molecules that modulate the host response toward a suppression state, creating an anti-inflammatory environment that promotes parasite survival
What are the 5 main mouthparts in insects?
- Labrum
- Mandible
- Labium
- Maxialle
- Hypopharynx
Name the 4 major insect CLADES
- Apterygota (silverfish)
- Pterygota –>
–> 3. Paleoptera
—> 4. Neoptera
Characteristics of the insect clade Apteryogota
WINGLESS
Characteristic of the insect clade Pterygota
WINGED
Characteristics of the insect clade Paleoptera
Wings CANNOT fold against body
Extensive venation.
Characteristics of the insect clade Neoptera
Wings CAN fold against body
Reduced venation