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08:26In some circumstances, the use of probiotics, which stimulate the rapid growth of bacteria that are mutualistic or commensal with humans, can eliminate the need to use antibiotics, which can wipe out helpful bacteria along with harmful bacteria. The use of probiotics is an example of which process?
a. Succession
b. Competitive exclusion
c. Parasitism
d. Niche differentiation
Suppose that a two-acre lawn on your college's campus is allowed to undergo succession. Describe how species traits, species interactions, and the site's history might affect the community that develops.
Lyme disease is caused by infections of the bacterium Borrelia burgdorferi (stained blue in the inset, among red blood cells), which is transferred to humans via blood-sucking bites from the tick Ixodes scapularis. Lyme disease can cause flu-like symptoms in the short term and more serious illnesses in the long term if not treated.
Why is Lyme disease on the rise in eastern North America?
In relation to humans, B. burgdorferi is a/an ____________ and the tick is a/an _____________.
a. endoparasite/ectoparasite
b. endoparasite/host
c. parasitoid/host
d. parasite/predator
Lyme disease is caused by infections of the bacterium Borrelia burgdorferi (stained blue in the inset, among red blood cells), which is transferred to humans via blood-sucking bites from the tick, Ixodes scapularis. Lyme disease can cause flu-like symptoms in the short term and more serious illnesses in the long term if not treated.
Why is Lyme disease on the rise in eastern North America?
Newly hatched ticks do not harbor B. burgdorferi. Rather, they pick it up from certain hosts that are reservoirs of the bacterium. When a larval tick crawls onto a host, it may get groomed off and killed by the host, or it may feed successfully, in which case it may or may not then become infected with B. burgdorferi. Felicia Keesing and others measured the rate of tick feeding and infection on different hosts.
What percentage of ticks on mice were infected with B. burgdorferi? What percentage of ticks on opossums were groomed off and killed?
The carnivorous plant Nepenthes bicalcarata ('fanged pitcher plant') has a unique relationship with a species of ant—Camponotus schmitzi ('diving ant'). The diving ants are not digested by the pitcher plants, but instead live on the plants and consume nectar. Diving ants also dive into the digestive juices in the pitcher, swim to the bottom, and capture and consume trapped insects, leaving uneaten body parts and ant feces behind.
What nutritional impact do the ants have on fanged pitcher plants?
Do the pitcher plants derive any nutritional benefit from this relationship?
Based on the background information presented here, does the relationship between diving ants and pitcher plants appear to be mutualistic? Explain.
Lyme disease is caused by infections of the bacterium Borrelia burgdorferi (stained blue in the inset, among red blood cells), which is transferred to humans via blood-sucking bites from the tick Ixodes scapularis. Lyme disease can cause flu-like symptoms in the short term and more serious illnesses in the long term if not treated.
Why is Lyme disease on the rise in eastern North America?
Deer are hosts of ticks but are not reservoirs of B. burgdorferi—their immune systems detect and kill the bacterium. But a tick with a prior bacterial infection can consume a blood meal from a deer and then bite and infect a human. The fitness effects of a deer on B. burgdorferi can be summarized as:
a. + because the deer supplies the bacterium with food.
b. − because the deer kills the bacteria in its blood.
c. + because the deer feeds and disperses the tick that can then infect a human with the bacterium.
d. − or + depending on whether the deer is the tick's last host.
