Parasites Flashcards
(17 cards)
definition for parasite.
An organism that feeds on or in another organism, the host. The parasite gains nutrition at the expense of the host
Define what is meant by an ectoparasite and an endoparasite.
Ectoparasite A parasite which feeds on a host.
Endoparasite A parasite that feeds in a host.
what is a primary and secondary host?
Primary host Where the adult form of the parasite develops.
Secondary host Where the larval/ intermediate stages are found.
what type of parasite is a head louse
ectoparasite
what do head louse feed on and its adaptations
Claws – to attach to hairs/ prevent removal from scratching
Gut – feeds by holozoic nutrition
Piercing mouthparts - feeds on blood
Male and Female individuals – A mate is easy to find
what type of parasite is a tapeworm
endoparasite
life cycle of a tapeworm
eggs released into environment into faeces
secondary host eats vegetation contaminated with tapeworm eggs
eggs hatch and larvae burrow through gut wall then carried in body
larvae develop into cysts in muscle
humans eat undercooked or raw meat and get infected
scolex develops and attaches to all of small intestine
adults grow and survive for many years
primary and secondary host in tapeworm
Primary host Human
Secondary host Pig
Describe how the tapeworm is adapted to prevent it being dislodged by peristalsis.
presence of hooks and suckers on scolex
embedded in wall of gut
Explain the absence of a digestive system is tapeworms.
surrounded by pre-digested food
does not need to digest food
can absorb products of digestion through its external surface
the body of a tapeworm is flattened.
increases surface area for absorption
decreases diffusion distance
how else is the further increase of surface area for absorption
the body surface is folded and has projections called microtrichs
why is mucus and other chemicals are secreted from the body surface
protection from digestive enzymes and acid / alkaline contents of gut
can inhibit enzymes
neutralise secretions
Explain why a tapeworm does not need another tapeworm to reproduce sexually.
tapeworms are hermaphrodite
produce both male and female gametes
can self-fertilise
Explain why such a large number of eggs are released in tapeworms.
increase the chance of infecting the secondary host
overall adaptations of a tapeworm
scolex/hooks/ suckers- to prevent removal (by peristalsis)/attach to gut wall
long and flat, no digestive system-Large sa: volume ratio to absorb pre-digested nutrients / pre-digested nutrients absorbed across {cuticle / body surface}
thick cuticle/mucus- to prevent digestion by host’s enzymes/immune system
hermaphrodite- self-fertilisation/ unable to find mate / allows them to reproduce
overall adaptations of head louse
Large number of eggs to increase size of population
claws (adult) / “glue” (eggs/nits)- to prevent removal (by scratching)/ to attach to hairs
holozoic- has gut for {digestion / absorption}
Piercing mouthparts- sucks blood
Separate sexes- as a mate is easy to find
