Question 1

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

Accepted Answer

Lyme disease is caused by the bacterium Borrelia burgdorferi and is transmitted through the bite of infected black-legged ticks, also known as deer ticks. The 2-year cycle of Lyme disease involves several hosts and stages of the tick's life cycle.

In the first year of the cycle, adult female ticks lay eggs in the environment. These eggs hatch into larvae, which then feed on small mammals such as mice and birds. During this feeding, the larvae may acquire the Borrelia burgdorferi bacterium from an infected host.

In the second year of the cycle, the infected larvae molt into nymphs. These nymphs then seek out a new host to feed on, which can include larger mammals such as deer, as well as humans. During this feeding, the infected nymphs can transmit the bacterium to their new host through their saliva.

Once infected, the new host can develop Lyme disease if the bacterium is not promptly removed. If the infected host is a tick, it can then go on to lay eggs and continue the cycle.

Overall, the 2-year cycle of Lyme disease involves the transmission of the bacterium between ticks and various hosts, including small mammals, larger mammals, and humans. This complex cycle contributes to the spread of Lyme disease in endemic areas.

Question 2

In S-I-R models, which of the following does NOT determine the proportion of S, I, and R individuals in a population?

Accepted Answer

A)  recovery of infected individuals 
B)  rates of transmission of the disease 
C)  acquisition of immunity 
D)  birth of new susceptible individuals 
A)  recovery of infected individuals 
B)  rates of transmission of the disease 
C)  acquisition of immunity 
D)  birth of new susceptible individuals A

Question 3

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

Accepted Answer

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

Question 4

Describe the differences between those organisms classified as endoparasites and those classified as ectoparasites. How does the difference between these two types of parasites provide an understanding of their life history?

Accepted Answer

Endoparasites are organisms that live in

Question 5

Dutch elm disease is caused by a

Accepted Answer

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

Question 6

Organisms that produce antibacterial or antifungal chemicals have developed this ability as the result of

Accepted Answer

A)  coevolution. 
B)  a parasite adaptation. 
C)  a host adaptation. 
D)  a prey adaptation. 
A)  coevolution. 
B)  a parasite adaptation. 
C)  a host adaptation. 
D)  a prey adaptation.

Question 7

Which species is a reservoir for Borrelia burgdorferi, the bacterium that causes Lyme disease?

Accepted Answer

A)  deer 
B)  mouse 
C)  dog 
D)  human 
A)  deer 
B)  mouse 
C)  dog 
D)  human

Question 8

Which of the following is NOT an example of horizontal transmission through a vector?

Accepted Answer

A)  transmission of the flu virus between adult humans 
B)  transmission of West Nile virus between bird conspecifics via a mosquito 
C)  transmission of HIV to a human infant from its mother via breast milk 
D)  transmission of liver fluke to a sheep via a helminth 
A)  transmission of the flu virus between adult humans 
B)  transmission of West Nile virus between bird conspecifics via a mosquito 
C)  transmission of HIV to a human infant from its mother via breast milk 
D)  transmission of liver fluke to a sheep via a helminth

Question 9

Parasites generally have _____ reproductive rates than their hosts and often _____ them.

Accepted Answer

A)  lower; do not kill 
B)  higher; do not kill 
C)  higher; kill 
D)  lower; kill 
A)  lower; do not kill 
B)  higher; do not kill 
C)  higher; kill 
D)  lower; kill

Question 10

Which of the following characterizes the rate of recovery of infected individuals in an S-I-R model?

Accepted Answer

A)  I ÷ g 
B)  I × g 
C)  I + g 
D)  I - g 
A)  I ÷ g 
B)  I × g 
C)  I + g 
D)  I - g

Question 11

Infection tolerance is the ability of a host to

Accepted Answer

A)  minimize harm that an infection can cause. 
B)  prevent infection by parasites. 
C)  prevent a parasite from reproducing. 
D)  recover from an existing infection. 
A)  minimize harm that an infection can cause. 
B)  prevent infection by parasites. 
C)  prevent a parasite from reproducing. 
D)  recover from an existing infection.

Question 12

A parasite moving between individuals other than parents and their offspring uses _____ transmission.

Accepted Answer

A)  horizontal 
B)  vertical 
C)  diagonal 
D)  vector 
A)  horizontal 
B)  vertical 
C)  diagonal 
D)  vector

Question 13

In S-I-R models of infectious disease transmission, R represents _____ individuals.

Accepted Answer

A)  resistant 
B)  recovered 
C)  relocated 
D)  resilient 
A)  resistant 
B)  recovered 
C)  relocated 
D)  resilient

Question 14

The World Health Organization estimates that more than _____ of all human deaths are caused by infectious diseases.

Accepted Answer

A)  30 percent 
B)  45 percent 
C)  25 percent 
D)  15 percent 
A)  30 percent 
B)  45 percent 
C)  25 percent 
D)  15 percent

Question 15

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

Accepted Answer

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

Question 16

Endoparasites (such as tapeworms) seem to lead an ideal life in the interior of the host, protected from natural enemies and the external environment while having a continual supply of nutrients. What are challenges that endoparasites face?

Accepted Answer

While it may seem like endoparasites hav

Question 17

The number of parasites of a given species that an individual host can harbor is its

Accepted Answer

A)  infection rate. 
B)  infection load. 
C)  parasite rate. 
D)  parasite load. 
A)  infection rate. 
B)  infection load. 
C)  parasite rate. 
D)  parasite load.

Question 18

While you are conducting a study of the optimal growing conditions for commercially grown sunflowers in Maryland, all of the sunflower plants in the field you are studying die. You discover that an emerging fungal pathogen kills sunflowers by destroying their roots. The fungus uses honeybees, which pollinate your flowers, as a vector to transmit fungal spores among sunflower plants. The next year the farm reseeds, hoping that the fungus has died over the winter. Early in the growing season some plants begin dying again, but then the honeybee population develops colony collapse disorder and all of the honeybees die. To compensate for the loss in pollinators, the farmers introduce large numbers of bumblebees. The number of new sunflower plants that become infected during the remainder of the growing season drops to near zero. Using the variables in the susceptible-infected-resistant (S-I-R) model equation: R0 = (S × I × g) ÷ (I × b), explain what has happened to alter the disease dynamics in the second year of your study and how this has occurred.

Accepted Answer

In the second year of the study, the int

Question 19

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

Question 20

Which of the following diseases has the highest R0 value?

Accepted Answer

A)  HIV 
B)  malaria 
C)  measles 
D)  chicken pox 
A)  HIV 
B)  malaria 
C)  measles 
D)  chicken pox

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.

In S-I-R models, which of the following does NOT determine the proportion of S, I, and R individuals in a population?

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

Describe the differences between those organisms classified as endoparasites and those classified as ectoparasites. How does the difference between these two types of parasites provide an understanding of their life history?

Dutch elm disease is caused by a

Organisms that produce antibacterial or antifungal chemicals have developed this ability as the result of

Which species is a reservoir for Borrelia burgdorferi, the bacterium that causes Lyme disease?

Which of the following is NOT an example of horizontal transmission through a vector?

Parasites generally have _____ reproductive rates than their hosts and often _____ them.

Which of the following characterizes the rate of recovery of infected individuals in an S-I-R model?

Infection tolerance is the ability of a host to

A parasite moving between individuals other than parents and their offspring uses _____ transmission.

In S-I-R models of infectious disease transmission, R represents _____ individuals.

The World Health Organization estimates that more than _____ of all human deaths are caused by infectious diseases.

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

Endoparasites (such as tapeworms) seem to lead an ideal life in the interior of the host, protected from natural enemies and the external environment while having a continual supply of nutrients. What are challenges that endoparasites face?

The number of parasites of a given species that an individual host can harbor is its

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

Which of the following diseases has the highest R0 value?

Introduction: Ecology, Evolution, and the Scientific Method

Adaptations to Aquatic Environments

Adaptations to Terrestrial Environments

Adaptations to Variable Environments

Climates and Soils

Terrestrial and Aquatic Biomes

Evolution and Adaptation

Life Histories

Reproductive Strategies

Social Behaviors

Population Distributions

Population Growth and Regulation

Population Dynamics Over Space and Time

Predation and Herbivory

Competition

Mutualism

Community Structure

Community Succession

Movement of Energy in Ecosystems

Movement of Elements in Ecosystems

Landscape Ecology and Global Biodiversity

Global Conservation of Biodiversity

Filters

Parasites generally have _ reproductive rates than their hosts and often _ them.

In S-I-R models, if R₀ > 1, the

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

Which of the following diseases has the highest R₀ value?