2.4.1-2 parasitism - niche and lifecycle Flashcards
what is an ecological niche
a multi dimensional summary of tolerances and requirements of a species
what is a fundamental niche
this is the niche a species occupies in the absence of any interspecific competition
when is a realised niche occupied
in response to interspecific competition
what happens as a result of interspecific competition
competitive exclusion can occur, where the niches of two species are so similar that one declines to local extinction
what happens once the realised niches are sufficiently different
potential competitors can co exist by resource partitioning
what is parasitism
a symbiotic interaction between a parasite and its host
who benefits in parasitism
a parasite gains benefit in terms of nutrients at the expense of its host
which organism has the greater reproductive potential - parasite or host
parasite
what does it mean that parasites are degenerate
they lack structures and organisms found in other organisms
what does it mean if a parasite is an endoparasite
lives within the tissues of its host
what does it mean if a parasite is an ectoparasite
lives on the surface of the host
do most parasites require one or many hosts to complete their lifecycle
many
what is the definitive host
the organism on or in which the parasite reaches sexual maturity
what role do vectors play
an active role in the transmission of the parasite and may also be a host
what does plasmodium cause
malaria
how does plasmodium cause malaria in humans
an infected mosquito, acting as a vector, bites a human.
plasmodium enters the human bloodstream
asexual reproduction occurs in the liver and then in the red blood cells
when the red blood cells burst, gametocytes are released into the bloodstream
another mosquito bites an infected human and the gametocytes enter the mosquito, maturing into male and female gametes, allowing sexual reproduction to now occur
the mosquito can then infect another human host
what causes the human disease schistosomiasis
schistosomes
how do schistosomes cause schistosomiasis in humans
they reproduce sexually in the human intestine.
fertilised eggs pass out via faeces into water where they develop into larvae
the larvae then infect water snails, where asexual reproduction occurs
this produces another type of motile larvae, which escape the snail and penetrate the skin of a human, entering the bloodstream
what are viruses
parasites that can only replicate inside a host cell
what do viruses contain
genetic material in the form of DNA or RNA, packaged in a protective protein coat
what are some viruses surrounded by
a phospholipid membrane derived from host cell materials
what does the outer surface of a virus contain
antigens that a host cell may or may not be able to detect as foreign
what are the stages of viral life cycle
infection of host cell with genetic material
host cell enzymes replicate viral genome
transcription of viral genes
translation of viral proteins
assembly and release of new viral particles
what do the RNA retroviruses use to form DNA
the enzyme reverse transcriptase
what happens once the RNA forms DNA
it is inserted into the genome of the host cell. viral genes can then be expressed to form new viral particles
