Deck 13: Parasitism

Question 1

What is the advantage for a male cricket parasitized by hairworms to seek out water?

A) By hydrating the cricket, the water decreases the negative effects of the parasite.
B) Female crickets live near the water; by going to the water, the infected cricket can increase his chances of mating before the parasite kills him.
C) There is no advantage for the cricket; the cricket's behavior is advantageous only to the parasite.
D) There is no advantage for the infected cricket, but by going to the water and drowning, the cricket reduces the prevalence of parasitism in the species.

Answer 1

C

Question 2

Which statement about enslaver parasites is false?

A) The manipulation of cricket behavior by hairworms reduces the survival of parasitized crickets.
B) Only invertebrates have been enslaved by parasites.
C) Enslaver parasites manipulate their hosts in order to further their transmission to the next host.
D) Several fungi species can alter the perching behavior of their fly hosts.

Answer 2

B

Question 3

A bacterium that lives inside an aphid is always classified as a(n)

A) parasite.
B) parasitoid.
C) symbiont.
D) endoparasite.

Answer 3

C

Question 4

Which statement is true?

A) All pathogens are parasites.
B) All parasites are pathogens.
C) All symbionts are parasites.
D) All symbionts are mutualists.

Question 5

Which parasite would most likely be found in the human small intestine?

A) Plasmodium
B) The pinworm Enterobius
C) The tapeworm Taenia saginata
D) The bacterium Mycobacterium

Question 6

Which statement about parasite natural history is false?

A) It is rare for a host species to have a parasite that feeds upon only that species.
B) Different parts of human bodies provide suitable habitat for a wide range of parasites.
C) Many species are host to more than one parasite species.
D) Both large and small parasites typically feed on one or a few host individuals.

Question 7

A bacterium that causes rash on the skin of mammals upon infection would be classified as a(n)

A) ectoparasite.
B) endoparasite.
C) parasitoid.
D) macroparasite.

Question 8

Nasonia vitripennis is a wasp roughly the size of a Drosophila fly. Adult females drill holes and lay eggs in the pupae of blowflies and related species. These eggs then hatch into larvae, which then eat the pupae. Thus, Nasonia vitripennis is a

A) hemiparasite.
B) parasitoid.
C) microparasite.
D) ectoparasite

Question 9

Which organism is an example of a hemiparasite?

A) Mistletoe
B) Head louse
C) Live fluke
D) Plasmodium

Question 10

Which of the following could not be a hemiparasite?

A) Any ectoparasite
B) Any macroparasite
C) Any microparasite
D) Any heterotroph

Question 11

Which statement about parasitic fungi, such as mildews, rusts, and smuts, is false?

A) At least some of these extract nutrients from their host plants through the use of hyphae.
B) Many of these species cause economic damage.
C) At least some of these are hemiparasitic.
D) At least some of these are ectoparasites.

Question 12

What do the fungus that causes athlete's foot, the tick that spreads Lyme disease, and body lice all have in common?

A) They are all ectoparasites.
B) They are all hemiparasites.
C) They are all microparasites.
D) They are all endoparasites.

Question 13

Which statement about endoparasites is true?

A) All endoparasites that infect animals are parasites of the alimentary canal.
B) All parasites living in the alimentary canal are endoparasites.
C) All endoparasites are microparasites.
D) All endoparasites have simple lifecycles that take place within a single host.

Question 14

Tapeworms have a _______, which they use to attach themselves to the insides of the host's intestine.

A) hypha
B) merozoite
C) scolex
D) boostrum

Question 15

Which statement about tuberculosis (TB) is false?

A) Recent advances in medicine and vaccines have cut the worldwide death rate from TB to less than 10,000 per year.
B) It is caused by the bacterium Mycobacterium tuberculosis.
C) It is one of two diseases that have killed more people than any other in human history.
D) It is a lung disease.

Question 16

Which of the following is an advantage that endoparasites have over ectoparasites?

A) Dispersal ability
B) Ease of feeding
C) Less susceptibility to the host's immune system
D) A simpler life cycle

Question 17

The most likely change caused by Vibrio cholerae in its hosts, which aids its dispersal to new hosts, is

A) diarrhea.
B) an increased tendency of the hosts to seek out predators.
C) coughing.
D) an increased tendency of the hosts to aggregate with conspecifics.

Question 18

As a budding scientist you discover a parasite associated with your favorite organism. To learn more about the parasite and the organism, you study them in depth, learning that the organism attacks the parasite using memory cells in an effort to prevent infection. Which type of mechanism is the organism utilizing as a defense against the parasite?

A) Defensive symbiont
B) Immune system
C) Biochemical defense
D) Gene counterdefense

Question 19

How does the protein transferrin assist in defenses against parasites?

A) It is used in encapsulating parasite eggs.
B) It removes iron from the blood serum in vertebrate hosts and stores it in intracellular compartments.
C) It paralyzes nematode parasites.
D) It allows "memory cells" of the immune system to store information about pathogens, thus providing lifelong immunity.

Question 20

Suppose that a vertebrate has a mutation in the transferrin gene that makes the protein function less efficiently. Most likely, compared to individuals without the mutation, this individual would have _______ iron in its blood serum and _______ iron in the intercellular components of cells.

A) more; more
B) less; less
C) less; the same amount of
D) more; less

Question 21

Refer to the figure.
Which aphid genotype with the symbiont present had a survival percentage closest to 35?

A) Aphid genotype 1
B) Aphid genotype 3
C) Aphid genotype 4
D) Aphid genotype 5

Question 22

Mosquitoes infected with Plasmodium carry cells of the _______ stage of the parasite. When an infected mosquito bites a human, these cells enter the _______, where they divide into _______ that then infect red blood cells.

A) merozoite; spleen; sporozoites
B) merozoite; liver; sporozoites
C) sporozoite; liver; merozoites
D) sporozoite; spleen; merozoites

Question 23

Which statement about malaria and the life cycle of Plasmodium is false?

A) The chills and fever associated with malaria arise from the rupturing of red blood cells by large numbers of merozoites.
B) The gamete-producing cells arise from sporozoites.
C) The gametes of Plasmodium unite to form a zygote within the mosquito host.
D) The typical zygotes produce thousands of sporozoites.

Question 24

In humans, red blood cells that have been infected with the parasite that causes malaria (Plasmodium) are destroyed mainly in the

A) spleen.
B) liver.
C) thymus.
D) kidney.

Question 25

In the years since Myxoma was introduced to Australia, the virus has _______ and rabbits have _______ resistance to the virus.

A) evolved to become more lethal; evolved
B) evolved to become more lethal; not changed in their level of
C) not changed in its lethality; evolved
D) evolved to become less lethal; evolved

Question 26

The studies by Dybdahl and Lively on snails and their parasites demonstrated that

A) snails evolve more quickly in response to parasites than parasites do to snails.
B) snails cannot evolve in response to parasites.
C) parasites infect common genotypes of snails more easily than they infect rare genotypes.
D) snails and parasites evolved at the same rate.

Question 27

Which statement about the snail-trematode system studied by Dybdahl and Lively is false?

A) Parasites infected snails from their home lake less effectively than those from other lakes.
B) The most common genotype of snail often varied from year to year.
C) The parasites can castrate male snails.
D) The type of parasite varied from year to year.

Question 28

Refer to the figure.
A population of rabbits has a mortality rate of 40%. The population would be hypothesized to have experienced _______ epidemics.

A) 0
B) 3
C) 5
D) 6

Question 29

Refer to the figure.
While sampling lakes in New Zealand for the number of snails infected with the Microphallus parasite, you get lost and aren't sure which lake you're sampling from. After returning to the lab, you identify the snails as Lake Paringa snails and determine the percentage of snails infected to be ~10%. Which lake did you most likely collect the snails from?

A) Lake Mapourika
B) Lake Wahapo
C) Lake Paringa
D) None of the data matches this scenario so it must not have been one of the three lakes.

Question 30

Which of the following is most likely to prevent or stop an arms race between host and parasite?

A) A trade-off between a host's survival in the absence of parasitism and its reproductive success in the absence of parasitism
B) A trade-off between a host's survival when parasitized and its reproductive success in the absence of parasitism
C) Rare genotypes of the host that make the host less resistant to parasitism
D) The absence of a trade-off between the host's survival and reproduction when parasitized

Question 31

Kraaijeveld and colleagues performed studies with Drosophila strains that can mount an encapsulation defense. In the absence of encapsulation, wasp eggs that have the ability to avoid encapsulation hatch _______ other eggs that cannot avoid encapsulation. These studies demonstrate _______.

A) faster than; the existence of trade-offs
B) faster than; coevolution
C) about the same as; coevolution
D) slower than; the existence of trade-offs

Question 32

The fungal parasite Cryphonectria parasitica is responsible for driving its host, the _______, to near extinction in North America.

A) American chestnut
B) passenger pigeon
C) ivory-billed woodpecker
D) spotted owl

Question 33

Refer to the figure.
The figure shows results from a study by Hudson and colleagues on red grouse and their nematode parasite. The figures show the cycling of six red grouse populations subjected to three treatments: (A) two control populations, (B) two populations treated for nematode parasites in 1989, and (C) two populations treated for parasites in 1989 and 1993. Each of the six grouse populations is designated by a different color. These results show that removal of the parasite

A) caused host populations to collapse.
B) reduced the fluctuations of the grouse population.
C) increased the fluctuations of the grouse population.
D) halted population cycles in the red grouse.

Question 34

In the context of host-parasite dynamics, a latent period is the time

A) delay that parasites impose on population cycles.
B) between infection in a host and its death or recovery.
C) between infection in a host and its own capacity to transmit the disease.
D) between infection in a host and the point at which it becomes symptomatic.

Question 35

In the simple host-pathogen model, which term describes the rate at which a disease is transmitted?

A) S
B) SI
C) $\beta$ SI
D) $\beta$ dI

Question 36

According to the basic host-pathogen model, if the combined death and recovery rate from a disease doubles, and the effectiveness of the disease to spread from infected to uninfected individuals also doubles, the threshold density should

A) decrease by a factor of four.
B) decrease by half.
C) stay the same.
D) double.

Question 37

According to the basic host-pathogen model, if the combined death and recovery rate from a disease doubles, and the effectiveness of the disease to spread from infected to uninfected individuals remains the same, the threshold density should

A) decrease by a factor of four.
B) decrease by half.
C) stay the same.
D) double.

Question 38

In the simple host-pathogen model, which term describes the rate at which a susceptible individual encounters an infected individual?

A) SI
B) S
C) dI
D) $\beta$ SI

Question 39

Suppose that the relative proportion of susceptible and infected individuals in a population remains the same, but the density of the overall population doubles. According to the SI model, disease transmission should

A) remain the same.
B) increase by the square root of two.
C) double.
D) quadruple.

Question 40

The transmission coefficient of the hypothetical disease Dirks fever is 0.8. If the combined death and recovery rate is 0.4, what is the threshold density for Dirks fever?

A) 0.32
B) 0.5
C) 0.8
D) 4

Question 41

Which of the following should reduce the critical threshold for the spread of disease?

A) Decreasing the transmission of coefficient $\beta$
B) Increasing the rate at which individuals die
C) Decreasing the rate at which individuals become immune
D) Increasing the density of susceptible individuals

Question 42

Based on the results of Dobson and Meagher's study of bison, which statement is false?

A) The threshold density in the wild was a herd of 200-300 bison.
B) The threshold density in the wild matched the estimated threshold density from the model.
C) Herd sizes in the wild were much greater than the threshold density.
D) The use of a vaccine successfully raised the threshold density.

Question 43

In which way can a parasite change an ecological community?

A) By forming a symbiotic relationship with the dominant competitor, causing the abundances of other species to stay the same
B) By not contributing to altering the physical environment in the area
C) By not changing the outcome of species interactions
D) By altering the composition of ecological communities

Question 44

Thomas Park's studies of flour beetles and their protozoan parasite best exemplified the principle that

A) parasites can alter the outcomes of competitive interactions between species.
B) there are costs to both host defenses and parasite counterdefenses.
C) selection can favor a diversity of host and parasite genotypes.
D) parasites can drive host populations to extinction.

Question 45

Refer to the figure.
Which of the following statements is true?

A) With the absence of Corophium volutator in May, the percent of silt content was higher than the amount of erosion.
B) With the absence of Corophium volutator in August, the percent of silt content was equal to the amount of erosion.
C) With the absence of Corophium volutator, the percent of silt content and the amount of erosion was unaffected.
D) With the absence of Corophium volutator, the percent of silt content remained the same while the amount of erosion continuously decreased.

Question 46

The Anopheles mosquito, which causes malaria, requires warm temperatures to complete the life cycle of Plasmodium falciparum. Which of the following statements is true?

A) If temperatures increase due to climate change, it is hypothesized that the incidences of malaria in humans and wildlife will increase.
B) If temperatures decrease due to climate change, it is hypothesized that the incidences of malaria in humans and wildlife will increase.
C) If temperatures increase due to climate change, it is hypothesized that the incidences of malaria in humans and wildlife will decrease.
D) If temperatures decrease due to climate change, it is hypothesized that the incidences of malaria will shift toward the poles.

Question 47

Refer to the figure.
A person living at 20^oN, 90^oW would

A) have the same risk of contracting leishmaniasis in 2009 as 2080.
B) have a decreased risk of contracting leishmaniasis in 2080 than in 2009.
C) be at risk of contracting leishmaniasis in 2009.
D) not be at risk of contracting leishmaniasis in 2009, but would be at risk in 2080.

Question 48

Humans have a long history of association with canines, which has led to the emergence of domestic dogs. Humans currently associate with dogs in different ways than they did historically. What type of relationship would a lap dog such as a Shih Tzu or a Chihuahua have with its owner? Could this relationship be considered parasitic?

Question 49

A flowering plant species and a honeycreeper (a type of bird) are both native to the Hawaiian Islands. The plant's flowers possess elongated curved structures with nectar at the base. The honeycreeper has a beak shape that matches the flower's size and shape and is traditionally the only pollinator of this species. A non-native bird species, however, (the Japanese white-eye) has recently been introduced to the Hawaiian Islands, and it is successful at extracting the nectar of the flowers despite having a short, straight bill. The white-eye creates a small hole near the base of the flowers thereby accessing nectar while bypassing the flower's reproductive structures. Would the white-eye be considered a parasite of the flower? Justify your answer.

Question 50

You are studying a population of a newly-discovered species. You suspect that one of the species you find growing on a tree is acting as a hemiparasite. If this species is indeed a hemiparasite, what types of structures would you expect to see? What kinds of data would you collect and what types of experiments would you conduct to test this hypothesis?

Question 51

Two parasites are found in a population of primates. Parasite 1 is an ectoparasite that can survive for up to 2 weeks off of the host. Parasite 2 is an endoparasite that can survive for 1 day outside of the host, but only in ideal conditions. How would the patterns and mode of spread differ between the two parasite species? What kinds of social behaviors would make these parasites more or less successful?

Question 52

Refer to the figure.
Figure 1
The figure shows data collected on a species of fish that lives on a coral reef. The fish were captured and studied three times-in 2000, 2005, and 2010. Four genotypes were found in an area of the coral reef (shown as A, B, C, and D). The figure shows: (1) the number of individuals of each genotype captured during each year, and (2) the percent of individuals infected with parasites captured during each year.

-Answer the following questions:
a) How does population size change over time for each of the four genotypes?
b) How does the percent of infected individuals change over time for each of the four genotypes?
c) Based on the percent of infected individuals of each genotype in each year, calculate the numbers of infected individuals. Create a new graph (this will be referred to as Figure 2) that reflects this data using the Figure 1 left, with each column reflecting a height that indicates the number of infected individuals.
d) What is the average infection rate across all genotypes for each study year? Create another new graph (this will be referred to as Figure 3) that reflects this data using Figure 1 right. Use an asterisk (*) to indicate the average infection rate for each year. Next, calculate the average of the average infection rate and add this data to the graph as a horizontal dotted line

Question 53

Refer to the figure.
Figure 1
The figure shows data collected on a species of fish that lives on a coral reef. The fish were captured and studied three times-in 2000, 2005, and 2010. Four genotypes were found in an area of the coral reef (shown as A, B, C, and D). The figure shows: (1) the number of individuals of each genotype captured during each year, and (2) the percent of individuals infected with parasites captured during each year.

-Answer the following questions:
a) Graph the relationship between the numbers of individuals of different genotypes and
the percent of infected individuals (this will be referred to as Figure 4). Refer to data on population size and percent of individuals infected by genotype. For simplicity, graph all of the data from all of the years on the same plot as points on a scatter graph. Sketch a line that fits the relationship between population size and percent infected.
b) What does this data tell you about the likely relationship between genotype, numbers of individuals, and the percent infected individuals?

Question 54

Refer to the figure.
Figure 1
The figure shows data collected on a species of fish that lives on a coral reef. The fish were captured and studied three times-in 2000, 2005, and 2010. Four genotypes were found in an area of the coral reef (shown as A, B, C, and D). The figure shows: (1) the number of individuals of each genotype captured during each year, and (2) the percent of individuals infected with parasites captured during each year.

-Suppose this reef fish is found on several reefs. Each reef is largely isolated from the others. The parasite species is found on all of these reefs. The frequencies of fish genotypes vary across the different reefs and the parasites rapidly evolve to be able to circumvent the fish's parasite defense mechanisms. Under which conditions might the parasites be more effective at colonizing individuals from its home reef, and when would parasites be more successful at colonizing individuals from another reef?

Question 55

Two populations (population 1 and population 2) are suffering from disease outbreaks that spread rapidly (disease 1 and disease 2). Population 1 is only affected by disease 1 and population 2 is only affected by disease 2. The two populations are the same size and the same density. In population 1, disease 1 is sexually transmitted, and in population 2, disease 2 is transmitted by an insect vector. What major difference would you expect to see in the pattern of disease transmission between the two populations? How would you expect seasonality or mating strategy to affect the spread of the diseases? What methods could you use to control the spread of disease in each case?

Question 56

Suppose you are studying disease transmission in two different populations. In both populations, an individual must be within 1 m of an infected individual in order for transmission to occur. How would you expect the spatial patterns of disease transmission to differ in a plant population versus an animal population? How would the spatial patterns of disease transmission affect options for controlling the spread of the disease in a population? Based on this transmission pattern, would it be easier to control the spread of the disease in a population of trees or in a population of mice? Explain your answers.

Question 57

Refer to the figure.
Suppose a turtle population is started from four individuals that disperse to a novel area. The figure shows the locations of each turtle in the native and novel areas and the type of parasites it carries. Each cell on the grid measures 1 m * 1 m. For this example, assume that each individual turtle can carry only one species of parasite at a time, and each individual carries a population of 100 individual parasites. The dashed circle and arrow indicate four individuals that moved to the novel area.Answer the following questions:
a) What effect did the founding of this novel turtle population have on the turtle's parasites? How did the total number of parasite species change during the move from the native to the novel area?
b) How would you expect turtle survival and growth rates in the novel area to be different from those in the native area if the presence of parasites has a negative effect on survival and growth rate?

Question 58

Which parasite alters the behavior of rats, such that they will seek out cats (which will likely capture and kill them)?

A) Plasmodium
B) Hairworm
C) Toxoplasma gondii
D) Hymenoepimecius argyraphaga

Question 59

Which characteristic best distinguishes microparasites from macroparasites?

A) Whether they live inside the host or on the host
B) Size
C) Whether they cause disease in humans
D) The number of different hosts in their life cycle

Question 60

Which statement about mistletoe is false?

A) It is a hemiparasite.
B) It is an endoparasite.
C) It relies on its host for water and mineral nutrients.
D) It can photosynthesize, and thus can generate its own carbohydrates.

Question 61

Evolution in a parasite from ectoparasitism to endoparasitism would most likely be caused by a(n) _______ in the number or intensity of natural enemies of the _______.

A) increase; host
B) decrease; host
C) increase; parasite
D) decrease; parasite

Question 62

Which characteristic is an advantage that ectoparasites have over endoparasites?

A) They can more easily disperse to other hosts.
B) They are less exposed to predators.
C) They are less exposed to changes in the external environment.
D) They can feed easier.

Question 63

Some plants protect themselves against specific parasites by means of _______. This defense system works much like the memory cells of the vertebrate immune system.

A) scolexes
B) immunity genes
C) merozoites
D) resistance genes

Question 64

A new strain of the malaria parasite Plasmodium is discovered, which has evolved a better counterdefense to increase its survival. Which of the following is not a possible evolutionary advance for this new Plasmodium strain?

A) A gene that allows Plasmodium to retain the host's red blood cell shape after infection
B) The injection of viruses into red blood cells, which makes the cells "invisible" to the host's immune system
C) The removal of genes from Plasmodium that produce knobs that are added to the surface of the red blood cells
D) Additional genes that allow transport proteins to be placed on the surface of red blood cells, enabling more nutrients to be imported into the infected host's red blood cells

Question 65

Suppose that a time machine allows you to go back in time (and to travel to Australia!), and you collect rabbits and myxoma from the years 1955 and 1980. Once you are back in the twenty-first century, you infect both sets of rabbits with both sets of myxoma viruses. The most likely result will be that (1) the rabbits from 1955 injected with the 1955 virus will have a _______ survival rate than those same rabbits injected with the 1980 virus; and that (2) the rabbits from 1955 injected with the 1980 virus will have a _______ survival rate than rabbits from 1980 injected with the 1980 virus.

A) higher; higher
B) lower; lower
C) lower; higher
D) higher; lower

Question 66

Which statement about the studies by Dybdahl and Lively on snails and their parasites is false?

A) The trematode preferentially infects snails with rare genotypes.
B) Parasites evolve more quickly in response to snails than snails evolve to parasites.
C) The trematode worm castrates males and sterilizes females.
D) The snail genotype that was most abundant at one point often changed from year to year.

Question 67

The interactions between the American chestnut and the parasitic fungus Cryphonectria parasitica best exemplify the principle that

A) parasites can drive host populations to extinction.
B) parasites can influence host population cycles.
C) selection can favor a diversity of host and parasite genotypes.
D) vaccination can reduce the incidence of disease.

Question 68

The transmission coefficient of the hypothetical disease Dumas fever is 0.2. If the combined death and recovery rate is 0.4, what is the threshold density for Dumas fever?

A) 0.2
B) 0.5
C) 0.8
D) 2

Question 69

According to the basic host-pathogen model of disease, if susceptible and infected individuals are the only types of individuals in a population, then disease transmission is greatest when susceptible individuals are _______ percent of the population. [Hint: If the density remains the same, when is SI maximized?]

A) 10
B) 25
C) 50
D) 90

Question 70

Refer to the figure.
Thomas Park studied competition between two species of flour beetles, both with and without their protozoan parasite. The figure shows the results of his experiment. Based on these results, when the beetles were infected with the parasite, _______ was the dominant competitor. In cases without the parasite, _______ was the dominant competitor.

A) T. castaneum; T. castaneum
B) T. confusum; T. castaneum
C) T. castaneum; T. confusum
D) T. confusum; T. confusum

Question 71

Climate change is predicted to have wide-ranging effects on species interactions and ultimately ecological communities. Which statement if true?

A) Climate change will not have any change on host-pathogen relationships.
B) Climate change may alter where a host lives but would have no effect on the pathogen.
C) If climate change alters a host's range, its pathogen may have to evolve with the host.
D) Climate change may alter where a pathogen is located, but would have no effect on the host's geographic range.

Question 72

Eberhard's study of spiders and their parasitoid wasps showed that the

A) wasps most likely change the web-building behavior of the spider by the injection of a fast-acting chemical.
B) type of web built is an all-or-nothing phenomenon; it is either a normal web or a cocoon web.
C) behaviors in spiders that build cocoon webs contain different elements than those that build normal webs.
D) chemical that causes alterations in web-building behavior is not dose dependent.