Parisitism

Question 1

parasite

Answer 1

consumes tissues or body fluid of the host

Harm, but don’t immediately kill, the organisms they eat

Question 2

endoparasite

Answer 2

lives inside its host

Question 3

ectoparasite

Answer 3

lives on outside of host

Question 4

Pathogens

Answer 4

microparasites that cause diseases

They do not directly consume the host tissue

Question 5

parasitoids

Answer 5

insects whose larvae feed on a single host and almost always kill it

Question 6

examples of diseases caused by parasites

Answer 6

influenza, tuberculosis, cholera, AIDS

Question 7

what does malaria success depend on

Answer 7

surviving in two hosts, developing into 3 different life forms, and being transmitted correctly

Question 8

example of single host parasite

Answer 8

tapeworm

Question 9

how can some parasites complete their life cycles

Answer 9

alter behaviour of host

Question 10

how can parasites improve transmission

Answer 10

change host mating system eg Wolbachia cause females to becoming parthenogenetic (unfertilized ovum develops directly into new individual)

Question 11

are parasites sufficient to explain the occurrence of cycles in host population sizes

Answer 11

cycle amplitude decreased with increasing application of anti-nematode drugs (anti-infection of nematodes)
Suggests nematode parasites shape (grouse) pop densities

Question 12

how else can parasites effect communities

Answer 12

affecting outcome of species interactions, can alter outcome of competition

Question 13

virulence

Answer 13

harm done by a parasite to its host following an infection

Question 14

why does virulence vary dramatically among pathogens ie some are lethal, some produce no symptoms

Answer 14

virulence changes and evolves in response to a number of variables
many observations are consistent with conventional wisdom hypothesis, others aren’t

Question 15

conventional wisdom hypothesis

Answer 15

given enough time a state of peaceful coexistence becomes established between host and parasite

Question 16

observation examples consistent with conventional hypothesis

Answer 16

lyme disease, ebola and SARS result from human infection with symbionts of other species that have recently jumped into humans

Question 17

observation examples not consistent with conventional wisdom

Answer 17

virulent pathogens eg gonorrhoea where humans are the unique or dominant hosts and vector
In malaria and tuberculosis, there is evidence of a long association with humans

Question 18

Trade off hypothesis

Answer 18

natural selection should favour strategy that maximises pathogen individual fitness
predicts trade off between rate of transmission and duration of infection
Assumes virulence is result of pathogen pop growth
Virulent strain of parasite may incr in frequency if, in the process of killing hosts, it sufficiently incr chances of being transmitted
Virulence should be result of optimal compromise between length of infection and growth to maximise transmission

Question 19

different ways for transmission to be accomplished

Answer 19

horizontal, sexual transmission

Question 20

which mode of transmission favours higher virulence

Answer 20

horizontal