Exercise 13 Flashcards
(22 cards)
Why are parasites so abundant and why do they tend to be specialists?
Most host species have multiple parasites and those parasites have parasites.
Parasites tend to be specialists because they live on or in their hosts.
Parasites tend to be specialists because they feed on certain parts of the host’s body.
All of the above
All of the above
What is an advantage of ectoparasitism?
Exposure to the external environment
Avoidance of natural enemies
Dispersal from one host individual to another
Ease of obtaining digested food of the host
Dispersal from one host individual to another
What is an advantage of endoparasitism?
Exposure to the external environment
Avoidance of natural enemies
Dispersal from one host individual to another
Exposure to the host’s immune system
Avoidance of natural enemies
Which is a mechanism that hosts do not use to defend themselves against parasites?
Resembling a palatable host
Immune system
Symbiont defense
Biochemical defenses
Resembling a palatable host
Some hosts are aided in their defense against parasites by bacteria and fungi. What best describes this defense?
Biochemical defense
Symbiont defense
Immune defense
Encapsulation
Symbiont defense
How can humans overcome the malaria parasite?
Encapsulation of the Plasmodium virus
Inject Plasmodium with virus-like particles
The spleen destroys red blood cells that contain Plasmodium
Red blood cells divide rapidly to starve the Plasmodium
The spleen destroys red blood cells that contain Plasmodium
Coevolution is when populations of two interacting species evolve in which of the following ways?
Separately, each in response to the selection pressures imposed by the other
Separately, each in response to the selection pressures imposed by the environment
Together, each in response to the selection pressures imposed by the environment
Together, each in response to the selection pressures imposed by the other
Together, each in response to the selection pressures imposed by the other
What factor(s) can affect the outcome of coevolution in host–parasite interactions?
The genetic diversity of the host
The mutation rate of the parasite
The lethality of the parasite
All of the above
All of the above
Why don’t host–parasite interactions show an ever-escalating coevolutionary arms race?
Each species has too much genetic diversity.
There is a trade-off in which a parasite’s counterdefenses have no costs to growth, reproduction, or survival.
There is a trade-off in which a host’s defenses have costs to growth, reproduction, or survival.
There is a trade-off in which a host’s defenses have no costs to growth, reproduction, or survival.
There is a trade-off in which a host’s defenses have costs to growth, reproduction, or survival.
Which study shows that parasites can cause population cycling in its host?
American chestnut and a parasitic fungus
Red grouse and nematode parasites
Amphipods and trematode parasites
Amphipods and trematode parasites
Red grouse and nematode parasites
Which factor is not considered in host–parasite population models?
The number of susceptible hosts
The number of infected hosts
The number of susceptible parasites
The number of recovered and immune hosts
The number of susceptible parasites
What are two ways to control the spread of a disease?
Decrease the susceptible hosts and increase the threshold density
Increase vaccines and programs that decrease the transmission rate
Kill or recover infected hosts
All of the above
All of the above
How can parasites or pathogens affect species interactions?
A host may become more susceptible to predation.
A host may be better able to catch its prey.
A host may be a better competitor.
Both a and c
A host may become more susceptible to predation.
When a population of the caddisfly Glossosoma nigrior was infected by a fungal pathogen, what were the community consequences and why?
A decrease in the abundance of dozens of species, all of which relied on the caddisfly
An increase in the abundance of dozens of species, all of which relied on the caddisfly
An increase in the abundance of dozens of species, all of which were negatively affected by herbivory of the caddisfly
An increase in the abundance of dozens of species, all of which were negatively affected by carnivory of the caddisfly
An increase in the abundance of dozens of species, all of which were negatively affected by herbivory of the caddisfly
What is one type of pathogen vector that might cause disease spread in humans during climate change and why?
Rodents benefiting from warmer conditions
Mosquitos benefiting from increasing CO2
Sand flies benefiting from increasing wet conditions
Mosquitos benefiting from warmer conditions
Mosquitos benefiting from warmer conditions
Suppose the researchers conducted another experiment to investigate whether other species of defensive symbionts can protect fruit flies from the nematode parasite Howardula. In the first experiment, they screened for beneficial symbiotic bacteria by searching for species similar to Spiroplasma bacteria. They first established a large population of fruit flies and exposed it to the nematode parasite. They then separated the fruit fly individuals into two groups: those without Howardula and those with Howardula. They screened individuals from both groups for seven species of symbionts (A–G). The results are shown in the table.
Experiment 1 Percentage of Fruit Fly Individuals with Different Species of Symbionts
Symbiont species
Treatment A B C D E F G
Howardula absent 50 40 80 30 50 95 30
Howardula present 50 90 10 30 75 95 96
Based on the data, which bacterial species appear to be defensive symbionts? Choose all that apply.
Species A
Species B
Species C
Species D
Species E
Species F
Species G
Species B,E,G
Experiment 1 Percentage of Fruit Fly Individuals with Different Species of Symbionts
Symbiont species
Treatment A B C D E F G
Howardula absent 50 40 80 30 50 95 30
Howardula present 50 90 10 30 75 95 96
Refer to the data provided above.
Which bacterial species may have been negatively affected by parasitism? Choose all that apply.
Species A
Species B
Species C
Species D
Species E
Species F
Species G
Species C
Refer to the information provided in the previous 2 questions.
Suppose in a second experiment the researchers follow, for seven generations, the percentage of fruit fly individuals that harbor the symbiont Species B with and without Howardula. They find the results shown in the table. Examine the data in the table. Do the results indicate that there is a cost to flies for harboring Species B symbiont?
Experiment 2 Percentage of Fruit Fly Individuals Harboring Species B Symbiont
Generation
Treatment 1 2 3 4 5 6 7
Howardula absent 39 43 30 22 15 6 1
Howardula present 75 80 86 92 97 99 99
There is no cost to flies for harboring species B symbiont because the symbiont protects the flies against Howardula.
There is no cost to flies for harboring Species B symbiont because the frequency of flies harboring the symbiont decline in the absence of the parasite.
There is a large cost to flies for harboring Species B symbiont because the frequency of flies harboring the symbiont decline in the absence of the parasite.
There is a large cost to flies for harboring Species B symbiont because the frequency of flies harboring the symbiont increases in the presence of the parasite.
There is a large cost to flies for harboring Species B symbiont because the frequency of flies harboring the symbiont decline in the absence of the parasite.
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?
0.4/0.8=0.5
Which of the following should reduce the critical threshold for the spread of disease?
Decreasing the transmission of coefficient
Increasing the rate at which individuals die
Decreasing the rate at which individuals become immune
Increasing the density of susceptible individuals
Increasing the rate at which individuals die
The Anopheles mosquito, which causes malaria, requires warm temperatures to complete the life cycle of Plasmodium falciparum. Which of the following statements is true?
If temperatures increase due to climate change, it is hypothesized that the incidences of malaria in humans and wildlife will increase.
If temperatures decrease due to climate change, it is hypothesized that the incidences of malaria in humans and wildlife will increase.
If temperatures decrease due to climate change, it is hypothesized that the incidences of malaria in humans and wildlife will increase.
If temperatures decrease due to climate change, it is hypothesized that the incidences of malaria will shift toward the poles.
If temperatures increase due to climate change, it is hypothesized that the incidences of malaria in humans and wildlife will increase.
What is the advantage for a male cricket parasitized by hairworms to seek out water?
By hydrating the cricket, the water decreases the negative effects of the parasite.
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.
There is no advantage for the cricket; the cricket’s behavior is advantageous only to the parasite.
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.
There is no advantage for the cricket; the cricket’s behavior is advantageous only to the parasite.
