higher biology - unit 3.5: symbiosis

symbiosis

the co-evolved intimate relationship between members of two different species

parasitism

a relationship between two organisms of different species where one benefits (parasite) and the other is harmed (host)

two categories of symbiotic relationships?

parasitism and mutualism

parasites often have limited...

metabolism and cannot survive out of contact with a host

transmission of parasites to new hosts can be by...

direct contact, resistant stages, vectors

direct contact

passed from human to human by physical contact e.g. head lice

resistant stages

able to survive adverse environmental conditions until they come into contact with a new host e.g. cat fleas

vectors

carries parasite from one host organism to another host organism

some parasitic lifestyles involve what to allow them to complete their lifestyle?

an intermediate (secondary) host

mutualism

an interdependent relationship which involves benefit for both species

types of mutualism

both provide a service, both gain a resource, one provides a service and one gains a resource