Question 1

Describe the 2-year cycle of Lyme disease, including all hosts and how the parasite is transmitted between hosts.

Accepted Answer

In year 1, a female tick lays eggs that hatch into larvae. The tick larvae parasitize a rodent that is infected with Borrelia burgdorferi. (Mice are a reservoir species.) The tick larvae become a vector of B. burgdorferi and molt into tick nymphs that overwinter in leaf litter. In year 2, the infected tick nymphs parasitize various animals (e.g., birds and humans). At this stage, humans and other tick hosts can be infected with B. burgdorferi and get Lyme disease. When the tick nymphs fall off and molt into adult ticks, they parasitize deer. While on the deer, adult ticks mate and adult females fall off and lay eggs to start the cycle again.

Question 2

The growth rates of two plant species are 5.3 millimetres per year for plant A and 4.6 millimetres per year for plant B. The t-statistic is calculated as 1.12, and the critical t for an alpha of 0.05 with 18 degrees of freedom is 1.734. What is concluded about the growth rates of the species?

Accepted Answer

A)   Species A has a significantly faster growth rate than species B.
B)   Species B has a significantly faster growth rate than species A.
C)   Species A and species B have similar growth rates.
D)   There is not enough information to make any determination about the growth rates of species A and species B.

Question 3

According to an S-I-R model, if a pathogen can kill its host

Accepted Answer

A)   the pathogen should decrease in abundance until hosts begin to die.
B)   the pathogen should increase in abundance until the hosts begin to die.
C)   the disease will not become an epidemic.
D)   the individuals in the population will either die or become resistant.

Question 4

The bacterium that causes chlamydia in humans can be transmitted from mother to fetus by _____ transmission or between any two individuals by _____ transmission.

Accepted Answer

A)   horizontal; horizontal
B)   vertical; vertical
C)   horizontal; vertical
D)   vertical; horizontal

Question 5

Which characterizes the rate of infection between susceptible and infected individuals in an S-I-R model?

Accepted Answer

A)   g × I × S
B)   g ÷ (I × S) 
C)   I + (S ÷ g) 
D)   S + (I × g)

Question 6

Question: Anthropologists studying a tribe on an island in the South Pacific ask you to help them with an intriguing health problem: the chiefs of the tribe keep dying at a much more rapid rate than other members of the population. You travel to the island to observe the tribe, and you find that each time an animal is killed during a hunt, the body of the animal is shared communally among all of the members of the tribe. However, one part of the animal, its brain, is reserved exclusively for the tribal chief. The chief consumes the brain raw because it is believed that this allows him to assimilate the animal's knowledge of the island. What would you suggest is causing the death of the tribal chiefs, how is it killing them, and what is the mechanism of transmission?

Accepted Answer

It is likely that a prion in the animal'...

Question 7

Which of the following strategies do schistosomes use to circumvent the host's immune system?

Accepted Answer

A)   They produce chemical factors that suppress their host's immune system.
B)   They produce surface proteins that mimic the host's own proteins.
C)   They continually produce novel surface proteins to confuse their host's immune system.
D)   They coat themselves with their host's proteins.

Question 8

The ability of a host to prevent infection by parasites is called

Accepted Answer

A)   tolerance.
B)   avoidance.
C)   resistance.
D)   reluctance.

Question 9

Dutch elm disease is caused by

Accepted Answer

A)   a fungus.
B)   a virus.
C)   a prion.
D)   a protozoan.

Question 10

(Figure 15.11) The graph shows survival rates for North American populations of the little brown bat (Myotis lucifugus) after exposure to either a North American or European strain of white-nose fungus (Geomyces destructans). What did researchers conclude about the two strains?

Accepted Answer

Exposure to either strain of white-nose fungus caused high rates of bat death. However, bats did not die as quickly when exposed to the North American strain, which may suggest that bats in North America are evolving some resistance to the North American strain of the fungus.
Parasite and host dynamics are determined by the parasite's ability to infect the host.

Question 11

How do reservoir populations allow parasites to persist in nature?

Accepted Answer

A)   Reservoir species transmit the parasite more frequently than host species, so the parasite infects a larger number of individuals.
B)   Reservoir species are necessary for reproduction of the parasite.
C)   Reservoir species do not die of the parasite and can be a continuous source of the parasite.
D)   Without the reservoir species, the parasite could not disperse from one host to another.

Question 12

Researchers set up an experiment in which they treat plants with a new fertilizer and compare plant height after 2 months to a control (untreated) group of plants. Using the data that follow, perform a t-test (α = 0.05) to determine whether the fertilizer affected plant height in this experiment. Use this formula:

Accepted Answer

Since the t-statistic for thes...

Question 13

The parasitic worm Acanthocephalus dirus has evolved an adaptation that causes its isopod host, Caecidotea intermedius, to

Accepted Answer

A)   spend more time out in the open.
B)   be attracted to larger fish.
C)   spend more time in refuges.
D)   be scared of larger fish.

Question 14

In S-I-R models, if the ratio of new infections to recoveries is less than 1,

Accepted Answer

A)   the infection becomes an epidemic.
B)   all individuals in the population become resistant to the infection.
C)   the infection fails to take hold in the host population.
D)   all infected individuals in the population recover.

Question 15

Crop rust is a _____ disease.

Accepted Answer

A)   protozoan
B)   prion
C)   viral
D)   fungal

Question 16

The prion that causes bovine spongiform encephalopathy is _____ transmitted _____.

Accepted Answer

A)   horizontally; via a mosquito vector
B)   vertically; from parent to offspring
C)   horizontally; via a helminth
D)   horizontally; directly via ingestion of infected cow tissue D

Question 17

Which of the following in NOT an example of an ectoparasite?

Accepted Answer

A)   a tick
B)   a tapeworm
C)   a flea
D)   a mite

Question 18

Which of the following is NOT a characteristic of an emerging infectious disease?

Accepted Answer

A)   high fatality rate
B)   recent discovery
C)   increased occurrence
D)   recent jump to a new host

Question 19

In S-I-R models, if R0 > 1,

Accepted Answer

A)   the infection fails to take hold in the host population.
B)   the population becomes resistant to the infection.
C)   the infection becomes an epidemic.
D)   the population is immune to the infection.

Question 20

Chimpanzees infected with intestinal worms sometimes eat Aspilia leaves. This is an example of

Accepted Answer

A)   coevolution.
B)   a reservoir species adaptation.
C)   a parasite adaptation.
D)   a host adaptation.

Exam 15: Parasitism and Infectious Diseases

Describe the 2-year cycle of Lyme disease, including all hosts and how the parasite is transmitted between hosts.

The growth rates of two plant species are 5.3 millimetres per year for plant A and 4.6 millimetres per year for plant B. The t-statistic is calculated as 1.12, and the critical t for an alpha of 0.05 with 18 degrees of freedom is 1.734. What is concluded about the growth rates of the species?

Correct Answer
verified

According to an S-I-R model, if a pathogen can kill its host

Correct Answer
verified

The bacterium that causes chlamydia in humans can be transmitted from mother to fetus by _ transmission or between any two individuals by _ transmission.

Correct Answer
verified

Which characterizes the rate of infection between susceptible and infected individuals in an S-I-R model?

Correct Answer
verified

Correct Answer
verified
It is likely that a prion in the animal'...
View Answer

Which of the following strategies do schistosomes use to circumvent the host's immune system?

Correct Answer
verified

The ability of a host to prevent infection by parasites is called

Correct Answer
verified

Dutch elm disease is caused by

Correct Answer
verified

(Figure 15.11) The graph shows survival rates for North American populations of the little brown bat (Myotis lucifugus) after exposure to either a North American or European strain of white-nose fungus (Geomyces destructans). What did researchers conclude about the two strains?

How do reservoir populations allow parasites to persist in nature?

Correct Answer
verified

Correct Answer
verified
Since the t-statistic for thes...
View Answer

The parasitic worm Acanthocephalus dirus has evolved an adaptation that causes its isopod host, Caecidotea intermedius, to

Correct Answer
verified

In S-I-R models, if the ratio of new infections to recoveries is less than 1,

Correct Answer
verified

Crop rust is a _____ disease.

Correct Answer
verified

The prion that causes bovine spongiform encephalopathy is _ transmitted _.

Correct Answer
verified
D

Which of the following in NOT an example of an ectoparasite?

Correct Answer
verified

Which of the following is NOT a characteristic of an emerging infectious disease?

Correct Answer
verified

In S-I-R models, if R₀ > 1,

Correct Answer
verified

Chimpanzees infected with intestinal worms sometimes eat Aspilia leaves. This is an example of

Correct Answer
verified

Exam 15: Parasitism and Infectious Diseases

Describe the 2-year cycle of Lyme disease, including all hosts and how the parasite is transmitted between hosts.

The growth rates of two plant species are 5.3 millimetres per year for plant A and 4.6 millimetres per year for plant B. The t-statistic is calculated as 1.12, and the critical t for an alpha of 0.05 with 18 degrees of freedom is 1.734. What is concluded about the growth rates of the species?

Correct AnswerverifiedShow Answer

According to an S-I-R model, if a pathogen can kill its host

Correct AnswerverifiedShow Answer

The bacterium that causes chlamydia in humans can be transmitted from mother to fetus by _____ transmission or between any two individuals by _____ transmission.

Correct AnswerverifiedShow Answer

Which characterizes the rate of infection between susceptible and infected individuals in an S-I-R model?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedIt is likely that a prion in the animal'...View AnswerShow Answer

Which of the following strategies do schistosomes use to circumvent the host's immune system?

Correct AnswerverifiedShow Answer

The ability of a host to prevent infection by parasites is called

Correct AnswerverifiedShow Answer

Dutch elm disease is caused by

Correct AnswerverifiedShow Answer

(Figure 15.11) The graph shows survival rates for North American populations of the little brown bat (Myotis lucifugus) after exposure to either a North American or European strain of white-nose fungus (Geomyces destructans). What did researchers conclude about the two strains?

How do reservoir populations allow parasites to persist in nature?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedSince the t-statistic for thes...View AnswerShow Answer

The parasitic worm Acanthocephalus dirus has evolved an adaptation that causes its isopod host, Caecidotea intermedius, to

Correct AnswerverifiedShow Answer

In S-I-R models, if the ratio of new infections to recoveries is less than 1,

Correct AnswerverifiedShow Answer

Crop rust is a _____ disease.

Correct AnswerverifiedShow Answer

The prion that causes bovine spongiform encephalopathy is _____ transmitted _____.

Correct AnswerverifiedD

Which of the following in NOT an example of an ectoparasite?

Correct AnswerverifiedShow Answer

Which of the following is NOT a characteristic of an emerging infectious disease?

Correct AnswerverifiedShow Answer

In S-I-R models, if R0 > 1,

Correct AnswerverifiedShow Answer

Chimpanzees infected with intestinal worms sometimes eat Aspilia leaves. This is an example of

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

The bacterium that causes chlamydia in humans can be transmitted from mother to fetus by _ transmission or between any two individuals by _ transmission.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
It is likely that a prion in the animal'...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
Since the t-statistic for thes...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

The prion that causes bovine spongiform encephalopathy is _ transmitted _.

Correct Answer
verified
D

Correct Answer
verified

Correct Answer
verified

In S-I-R models, if R₀ > 1,

Correct Answer
verified

Correct Answer
verified