Question 1

Chemical defenses are an important part of plant-herbivore interactions. The production of these chemical defense compounds results in an energetic cost to the organism. Which of the following statements explains how natural selection resulted in the evolution of these chemical compounds?

Accepted Answer

A)  The production of chemical compounds requires nitrogen. Nitrogen used to make these compounds cannot be used to make proteins.
B)  The energetic cost of producing chemical compounds is reduced because only small amounts of each chemical are needed to have their desired effects.
C)  Individuals that produce chemical compounds are better protected from herbivores and are able to produce more young than individuals that do not produce the compounds.
D)  Plants produce amino acids that are not incorporated into their own proteins, but herbivorous insects do incorporate these amino acids into their own proteins, rendering the herbivores' proteins nonfunctional.

Question 2

Which of the following is NOT a mechanical defense employed by plants?

Accepted Answer

A)  hairs
B)  silica plates
C)  thorns
D)  terpenes
E)  spines

Question 3

Some plant species are capable of attracting or supporting insect predators of insect herbivores. Which of the following may play a role in this form of defense?

Accepted Answer

A)  volatile chemicals released by damaged tissue
B)  nectaries
C)  thorns
D)  All of these choices are correct.

Question 4

A seed from a yew tree germinates on the forest floor. During the first few months of its life, the sapling dedicates most of its resources to increasing in height rather than producing the defensive compound taxol. What is this allocation of resources an example of?

Accepted Answer

A)  a symbiosis
B)  a trade-off
C)  a constitutive defense
D)  an inducible defense
E)  a basal response

Question 5

Which of the following statements are consistent with the "escape and radiate hypothesis" of Ehrlich and Raven?

Accepted Answer

A)  a species that evolves a novel, highly effective form of defense will be able to successfuly invade new habitats
B)  new defenses that release a species from the intense selective pressures exerted by herbivores will lead to higher genetic diversity
C)  populations that "escape" herbivory by invading new habitats are free to evolve novel forms of defense that result in new species
D)  interactions between plants and animals lead to higher diversity than one might expect based only on animal-animal or plant-plant competition

Question 6

A researcher comes across a plant that has been infected by a pathogen. As a result of the infection, the plant has undergone a systemic acquired resistance (SAR)  response and has also generated several siRNAs. Based on this response, what type of pathogen MOST likely infected the plant?

Accepted Answer

A)  a bacterium
B)  a virus
C)  a fungi
D)  an oomycete
E)  a parasitic plant

Question 7

Pesticide use has grown a great deal in the past century, and similar to the plant-herbivore evolutionary "arms race":

Accepted Answer

A)  increased use of pesticides is leading to increased rates of resistance.
B)  widespread chemical treatments pose little concern because they wipe out all existing herbivores.
C)  pesticides are killing pests and their predators, reducing the overall level of herbivory in crop plants.

Question 8

When a coyote tobacco plant releases volatile signals in response to M. sexta caterpillars, this is an example of a(n)  _____. The presence of hairs on the leaf of a milkweed plant is an example of a(n)  _____.

Accepted Answer

A)  constitutive defense; inducible defense
B)  SAR response; basal response
C)  basal response; SAR response
D)  inducible defense; constitutive defense

Question 9

Which of the following is NOT analogous to a sensory pathway by which plants can detect herbivores?

Accepted Answer

A)  taste
B)  smell
C)  sound
D)  sight

Question 10

Some plants gain their nutrition by parasitizing other plants.

Accepted Answer

A) True 
 B)False

Question 11

Which of the following is NOT a way we can intentionally modify the genetic makeup of a cultivated species to protect it from herbivores?

Accepted Answer

A)  crop breeding by manually making artificial crosses for desirable traits
B)  using bacteria to genetically introduce new genes into the plant
C)  importing new seed stock from other areas and crossing it with existing plants
D)  using viruses to insert novel defense genes into the plant
E)  spraying with chemical pesticides

Question 12

Latex or resin canals evolved independently in more than 40 different groups of plants.

Accepted Answer

A) True 
 B)False

Question 13

Which of the following is NOT part of plant defense systems against pathogens?

Accepted Answer

A)  Protein receptors detect a broad class of molecules produced by many pathogens and mount defense mechanisms.
B)  R proteins inside plant cells recognize AVR proteins from pathogens.
C)  Plants reinforce barriers, such as by closing stomata and reinforcing cell walls.
D)  Cells surrounding the infection site produce reactive oxygen species.
E)  Plants produce AVR proteins when invaded by a pathogen.

Question 14

Which of the following organisms can act as plant pathogens?

Accepted Answer

A)  mistletoe
B)  nematodes
C)  tobacco plants
D)  bacteria
E)  P)  ferruginea ants

Question 15

Volatile chemicals that escape from plants into the air:

Accepted Answer

A)  assist some parasitic plants in locating their host.
B)  can attract predators to an herbivore-damaged plant.
C)  may play a role in systemic acquired resistance.
D)  are never simply released due to tissue damage with no adaptive function.

Question 16

You are asked to evaluate a research proposal that aims to increase the resistance of wheat to a new stem rust by inserting R-genes from another plant, a wild relative of potato, known to be highly resist to rust. Do you recommend the proposal be funded, and why?

Accepted Answer

A)  Yes, because the additional R-genes will likely improve the ability of wheat plants to recognize the rust pathogen.
B)  Yes, because these R-genes come from a distantly related plant lineage, it is unlikely that this wheat rust will have evolved a way to evade them.
C)  No, because these R-genes come from a distantly related plant lineage, they are unlikely to function properly in wheat.
D)  No, because R-genes only confer resistance when expressed in the same species they evolved in.

Question 17

A plant's fitness is directly related to its ability to deter predators; the more it invests in defenses, the higher its fitness.

Accepted Answer

A) True 
 B)False

Question 18

Ehrlich and Raven proposed an "escape and radiate" hypothesis that predicts that:

Accepted Answer

A)  plant species that evolve novel defenses against their herbivores are more likely to diversify into new species.
B)  plant species that are not eaten will develop more similar traits.
C)  plant and insect species coevolve toward less species diversity.
D)  a plant species will only win an evolutionary "arms race" if it escapes to new a habitat.
E)  plant and insect within-species diversity tends to decrease through time as each adapts to the other's defenses.

Question 19

The observation that agricultural pests are evolving resistance to the Bt toxins suggests that farmers should plant _____ of their fields with non-Bt- producing varieties.
A)more
B)less

Accepted Answer

A) True 
 B)False

Question 20

Plants can have _____ defenses, which are always active, or _____ defenses, which are produced only when a plant is threatened.

Accepted Answer

A)  inducible; constitutive
B)  constitutive; inducible
C)  chemical; mechanical
D)  mutualistic; symbiotic

Exam 32: Plant Defense: Keeping the World Green

Which of the following statements are consistent with the "escape and radiate hypothesis" of Ehrlich and Raven?

Correct AnswerverifiedShow Answer

Latex or resin canals evolved independently in more than 40 different groups of plants.

Correct AnswerverifiedShow Answer

The observation that agricultural pests are evolving resistance to the Bt toxins suggests that farmers should plant _____ of their fields with non-Bt- producing varieties. A)more B)less

Correct AnswerverifiedShow Answer

A researcher comes across a plant that has been infected by a pathogen. As a result of the infection, the plant has undergone a systemic acquired resistance (SAR) response and has also generated several siRNAs. Based on this response, what type of pathogen MOST likely infected the plant?

Correct AnswerverifiedShow Answer

Some plant species are capable of attracting or supporting insect predators of insect herbivores. Which of the following may play a role in this form of defense?

Correct AnswerverifiedShow Answer

A plant's fitness is directly related to its ability to deter predators; the more it invests in defenses, the higher its fitness.

Correct AnswerverifiedShow Answer

Ehrlich and Raven proposed an "escape and radiate" hypothesis that predicts that:

Correct AnswerverifiedShow Answer

A seed from a yew tree germinates on the forest floor. During the first few months of its life, the sapling dedicates most of its resources to increasing in height rather than producing the defensive compound taxol. What is this allocation of resources an example of?

Correct AnswerverifiedShow Answer

Plants can have _____ defenses, which are always active, or _____ defenses, which are produced only when a plant is threatened.

Correct AnswerverifiedShow Answer

When a coyote tobacco plant releases volatile signals in response to M. sexta caterpillars, this is an example of a(n) _____. The presence of hairs on the leaf of a milkweed plant is an example of a(n) _____.

Correct AnswerverifiedShow Answer

Pesticide use has grown a great deal in the past century, and similar to the plant-herbivore evolutionary "arms race":

Correct AnswerverifiedShow Answer

Which of the following is NOT a mechanical defense employed by plants?

Correct AnswerverifiedShow Answer

Some plants gain their nutrition by parasitizing other plants.

Correct AnswerverifiedShow Answer

Which of the following is NOT analogous to a sensory pathway by which plants can detect herbivores?

Correct AnswerverifiedShow Answer

You are asked to evaluate a research proposal that aims to increase the resistance of wheat to a new stem rust by inserting R-genes from another plant, a wild relative of potato, known to be highly resist to rust. Do you recommend the proposal be funded, and why?

Correct AnswerverifiedShow Answer

Which of the following is NOT part of plant defense systems against pathogens?

Correct AnswerverifiedShow Answer

Volatile chemicals that escape from plants into the air:

Correct AnswerverifiedShow Answer

Chemical defenses are an important part of plant-herbivore interactions. The production of these chemical defense compounds results in an energetic cost to the organism. Which of the following statements explains how natural selection resulted in the evolution of these chemical compounds?

Correct AnswerverifiedShow Answer

Which of the following organisms can act as plant pathogens?

Correct AnswerverifiedShow Answer

Which of the following is NOT a way we can intentionally modify the genetic makeup of a cultivated species to protect it from herbivores?

Correct AnswerverifiedShow Answer

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Plants can have _ defenses, which are always active, or _ defenses, which are produced only when a plant is threatened.

Correct Answer
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When a coyote tobacco plant releases volatile signals in response to M. sexta caterpillars, this is an example of a(n) _. The presence of hairs on the leaf of a milkweed plant is an example of a(n) _.

Correct Answer
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