Chapter 14
1. A species feeding on the tissue of its host, while not killing it directly, is a
a) predator.
b) parasite.
c) parasitoid.
d) cannibal.
e) debilitator.
Answer: B
2. An organism inducing disease in its host is called a ______________.
Answer: pathogen
3. A “negatively phototaxic” amphipod will swim
a) away from parasitic worms.
b) towards parasitic worms.
c) away from competing amphipods.
d) towards light.
e) away from light.
Answer: E
4. Plagiorhynchus worms and Puccinia rusts are parasites that share the ability to change
their hosts behavior in way that
a) increase the length of time they can survive in their hosts.
b) decrease their hosts mortality rates.
c) increase their hosts reproduction, thereby increasing production of parasite-infected
offspring.
d) increase the likelihood of their (the parasites’) transmission to a new host.
e) decrease the hosts’ vulnerability to other parasites.
Answer: D
5. The presence of parasitic protozoa in a culture of competing Tribolium castaneum and
T. confusum
a) increases the likelihood of coexistence.
b) decreases the likelihood of coexistence.
c) has no effect on the outcome of competition.
d) can reverse the outcome of competition.
e) has an effect on the outcome of competition only in the presence of predatory birds.
Answer: D
6. The infestation of prickly pear cactus (Opuntia) in Australia was controlled by the
release of a moth, Cactoblastis, which impacts cactus populations because it
a) consumes cactus seeds.
b) consumes cactus pads.
c) introduces, as it attacks, fungi and bacteria that attack cactus pads.
d) Both consumes cactus seeds and consumes cactus pads.
e) both consumes cactus pads and introduces, as it attacks, fungi and bacteria that attack
cactus pads.
Answer: E
7. The standard error of the mean is equal to
a) the sample variance divided by the sample size.
b) the sample variance divided by the square root of the sample size.
c) the sample standard deviation divided by the square root of the sample size.
d) twice the square root of the sample size.
e) twice the square root of the sample variance.
Answer: C
8. Which statement about snowshoe hare and lynx populations in boreal Canada is false?
a) Lynx are the not only important predator of snowshoe hares.
b) Lynx and hare populations both oscillate repeatedly, with a similar period.
c) Snowshoe hares rarely deplete their food supply enough to affect their population
biology.
d) Trapping records kept by non-scientists can provide useful records of hare population
sizes.
e) Field experiments imply that hare cycles depend both on the hares’ food and their
predators.
Answer: C
9. In the Lotka-Volterra predation model, a prey (host) population in the absence of
predators would
a) grow exponentially.
b) grow logistically.
c) grow exponentially, and then crash when it has outstripped its own food supply.
d) decline to extinction.
e) the model makes no assumptions about what happens in the absence of predators.
Answer: A
10. In the Lotka-Volterra predation model, a predator population in the absence of prey
(hosts) would
a) grow exponentially.
b) grow logistically.
c) decline as predators die.
d) decline at first, but then increase as predators switch to other modes of feeding.
e) decline at first, but then reach a small equilibrium population size.
Answer: C
11. In the Lotka-Volterra predation model, the predator death rate is represented by
a) c.
b) p.
c) cp.
d) dpNp.
e) dp.
Answer: E
12. The Lotka-Volterra predation model predicts that predators and prey, living together,
will show
a) oscillations in population size that increase in amplitude through time.
b) oscillations in population size that remain of constant amplitude through time.
c) oscillations in population size that decrease in amplitude through time.
d) oscillations, but only when outside forces such as climatic variation are also present.
e) steady equilibria in population sizes.
Answer: B
13. In most laboratory experiments, predators and prey held together in simple habitats
exhibit repeated cycles in population sizes.
Answer: F
14. Gause’s experiments with Paramecium and Didinium showed
a) extinction of the predator, followed by extinction of the prey, in all habitats.
b) coexistence of predator and prey at fairly constant population sizes, in all habitats.
c) coexistence of predator and prey, but with oscillating population sizes, in all habitats.
d) coexistence of predator and prey at fairly constant population sizes, but only in the
presence of refuges and predator reservoirs.
e) coexistence of predator and prey with oscillating population sizes, but only in the
presence of refuges and predator reservoirs.
Answer: E
15. Which of the following factors can stabilize predator-prey relationships by providing
a prey refuge?
a) an area of prey habitat where predators cannot enter
b) an area of prey habitat that is isolated and difficult for predators to find
c) the occurrence of prey in numbers too large for predators to attack effectively
d) the ability of prey to grow to a size invulnerable to predation
e) all of the above
Answer: E
16. Synchronous production of large quantities of seed by plant populations over wide
areas is called ___________.
Answer: masting
17. Periodical cicadas spend 13 or 17 years
a) feeding in tree twigs before emerging as adults.
b) feeding on tree roots before emerging as adults.
c) as adults before laying eggs.
d) in a resistant, resting egg before hatching as larvae.
e) none of the above
Answer: B
18. Ephemerellid mayflies under attack by stoneflies will typically
a) swim away to escape possible predation.
b) rely on their cryptic coloration to escape detection.
c) rely on their spiny appendages to deter attack.
d) adopt a posture which increases their apparent size, so that the predator will avoid
them.
e) burrow into the stream bottom.
Answer: D
19. The two most globally prevalent parasitic diseases of humans are _________ and
_________.
Answer: malaria and schistosomiasis
20. Schistosoma flukes attack their human hosts when those humans
a) consume infected freshwater snails.
b) consume infected fish.
c) consume plant tissue bearing spores.
d) bathe in water containing infective cercariae.
e) urinate near bodies of water containing infected snails.
Answer: D
21. Use of Procambarus crayfish to combat schistosomiasis in Africa
a) is likely to be effective, and poses no important ecological risks.
b) is likely to be effective, but poses ecological risks because Procambarus is not native
to Africa.
c) is unlikely to be effective, because the crayfish seem to eat infected snails only in the
laboratory.
d) is unlikely to be effective, because the crayfish are just as suitable as hosts for the
parasite as were the snails.
e) is unlikely to be effective, because the crayfish cannot survive in African ponds.
Answer: B