Sub 8: Symbiosis

Question 1

what is symbiosis?

Answer 1

relationships between organisms where there is some benefit (or harm) to one or more of the organisms involved

Question 2

what are the three categories of symbiotic interactions?

Answer 2

mutualism, commensalism, parasitism

Question 3

what is parasitism? who benefits and why?

Answer 3

relationship between a parasite and a host. is beneficial to the parasite as it gains energy and nutrients but detrimental to the host as it loses energy and resources

Question 4

what is an obligate parasite?

Answer 4

parasite is dependent on the host in order to survive

Question 5

what is a facultative parasite?

Answer 5

parasite that does not need a host to survive, can live both with or without a host

Question 6

what are ectoparasites?

Answer 6

live on the surface of their hosts

Question 7

what are endoparasites?

Answer 7

live within their hosts

Question 8

what is vertical transmission of a parasite?

Answer 8

passed from mother to offspring

Question 9

what is horizontal transmission of a parasite?

Answer 9

direct contact
resistant stages - dormant at first, when consumed by appropriate host it becomes active
vectors - carrier

Question 10

what is Koch’s postulates?

Answer 10

about identifying what organism is causing the disease

Question 11

describe Koch’s postulates

Answer 11

same pathogen should be present in all diseased organisms and absent from healthy ones
organism should be isolated from the diseased host and grown in a pure culture
inoculating a healthy individual with the pure culture induces the same disease in that organism
pathogen reisolated from the host in which the disease has been induced to confirm that it is the same disease as used in the inoculum

Question 12

what is commensalism?

Answer 12

biotic interaction that is beneficial to the organism, the commensal whilst the other is unaffected. +/0 interaction

Question 13

give examples of commensalism

Answer 13

birds and grazing animals

sea anemone and clownfish

Question 14

why is it so difficult to achieve true commensalism?

Answer 14

although an organism gains from the interaction, the other is not always completely unharmed
the organism may not be significantly harmed but may suffer slight energy loss by feeding or carrying another organism

Question 15

what is true commensalism?

Answer 15

when the commensal utilises either dead part of the host or the host’s waste

Question 16

what is mutualism?

Answer 16

relationship where both organisms benefit from the interaction. +/+

Question 17

give examples of mutualism

Answer 17

sea anemone and hermit crab

rhizobium and legume plants