exam 2

Question 1

.9) People with at least one copy of the HLA-B53gene are better able to beat back malarial infections before the infection progresses. If this is a coevolutionary arms race between Plasmodiumand humans, what would the next step in this race be?

Answer 1

) to see Plasmodium populations that counter the HLA-B53

Question 2

0) As you study two closely related predatory insect species, the two-spot and the three-spot avenger beetles, you notice that each species seeks prey at dawn in areas without the other species. However, where their ranges overlap, the two-spot avenger beetle hunts at night and the three-spot hunts in the morning. When you bring them into the laboratory and isolate the two different species, you discover that the offspring of both species are found to be nocturnal. You have discovered an example

Answer 2

) resource partitioning

Question 3

Which of the following statements is a valid conclusion of this experiment?

Answer 3

The removal of Balanus shows that the realized niche of Chthamalus is smaller than its
fundamental niche

Question 4

Connell conducted this experiment to learn more about _____.

Answer 4

competitive exclusion and distribution of barnacle species

Question 5

The symbols +, -, and o are to be used to show the results of interactions between individuals and
groups of individuals in the examples that follow. The symbol + denotes a positive interaction, -
denotes a negative interaction, and o denotes where individuals are not affected by interacting.
The first symbol refers to the first organism mentioned.
13) What interactions exist between a lion pride and a hyena pack?

Answer 5

E) -/-

Question 6

What interactions exist between a tick on a dog and the dog?

Answer 6

+/-

Question 7

Which of the following statements is consistent with the principle of competitive exclusion?

Answer 7

Even a slight reproductive advantage will eventually lead to the elimination of the less well
adapted of two competing species

Question 8

Which statement best describes the evolutionary significance of mutualism?

Answer 8

Interaction increases the survival and/or population growth rate(s) of mutualistic species

Question 9

) In biology, an arms race occurs when ____

Answer 9

there is a repeating cycle of reciprocal adaptation

Question 10

18) The competitive exclusion principle states that

Answer 10

it is not possible for two species with the same niche to coexist in the same region

Question 11

What is the term used to describe the process shown in the panels in the figure above,
assuming Time 2 follows Time 1?

Answer 11

niche differentiation

Question 12

20) In the figure above, which species is the stronger competitor?

Answer 12

A) species 1

Question 13

) If two species are close competitors, and one species is experimentally removed from the
community, the remaining species would be expected to _____.

Answer 13

E) expand its realized niche

Question 14

) Which of the following support(s) the observation that herbivores do not generally eat all of
the available plants
I) top-down control hypothesis
II) poor nutrition hypothesis
III) plant-defense hypothes

Answer 14

E) I, II, and III

Question 15

Which of the following is an example of a commensalism?

Answer 15

cattle egrets eating insects stirred up by grazing bison

Question 16

Treehoppers (a type of insect) produce honeydew, which ants use for food. Treehoppers have
a major predator, the jumping spider. Researchers hypothesized that the ants would protect the
treehoppers from the spiders. In an experiment, researchers followed study plots with ants
removed from the system and compared them to a control plot. In the figure above, what can you
conclude?

Answer 16

Ants do somehow protect the treehoppers from spiders.

Question 17

During a one-year study, researchers found no difference in treehopper populations in any of
their control and experimental groups. What could they measure during the second year to gain
information about why this might have occurred?

Answer 17

Measure the relative abundance of jumping spiders.

Question 18

Which one of the following is a type of species interaction with impacts that depend on prey
density and effectiveness of defenses to determine the short-term impact on the prey population?

Answer 18

consumption

Question 19

What does the graph in the figure above tell you about the definition of a keystone species?

Answer 19

Removing a keystone species from the community drastically reduces diversity

Question 20

Recall that Clements’s view of biological communities is that of a highly predictable and
interrelated structure, while Gleason’s view of biological communities is that individual species
operate independently. If we set up many identical sterilized ponds in the same area and allowed
them to be colonized, what should we predict if we wished to test Gleason’s hypothes

Answer 20

Different plankton communities will develop in all ponds.

Question 21

Looking at the results in the figure above, which hypothesis (by Clements or Gleason) is
supported by the data?
I) Clements
II) Gleason

Answer 21

C) both I and II

Question 22

Which one of the following animals would most likely be defined as a keystone species?

Answer 22

A) sea otter

Question 23

Which of the following would be most significant in understanding the structure of an
ecological community?
I) determining how many species are present overall
II) determining which particular species are present
III) determining the kinds of interactions that occur among organisms of different species
IV) determining the relative abundance of species

Answer 23

I, II, III, and IV

Question 24

n a tide pool, fifteen species of invertebrates were reduced to eight after one species was
removed. The species removed was likely a(n) _____.

Answer 24

keystone species

Question 25

Elephants are not the most dominant species in African grasslands, yet they influence
community structure. The grasslands contain scattered woody plants, but they are kept in check
by the uprooting activities of the elephants. Take away the elephants, and the grasslands convert
to forests or to shrublands. The newly growing forests support fewer species than the previous
grasslands. Which of the following describes why elephants are the keystone species in this
scenario?

Answer 25

Elephants exhibit a disproportionate influence on the structure of the community relative to
their abundance.

Question 26

According to bottom-up and top-down control models of community organization, which of
the following expressions would imply that an increase in the size of a carnivore (C) population
would negatively impact its prey (P) population, but not vice versa

Answer 26

P ← C

Question 27

Keystone predators can maintain species diversity in a community if they _____.

Answer 27

prey on the community’s dominant species

Question 28

What is the main difference between a disturbance and a disturbance regime?

Answer 28

A disturbance regime includes defining the predictable frequency and severity of the
disturbance.

Question 29

What is the main advantage of controlled burnings of forested areas? Controlled burnings
____

Answer 29

C) prevent the overgrowth of the underbru

Question 30

Which of the following terms is used by ecologists to describe the community interaction
where one organism makes the environment more suitable for another organism

Answer 30

D) facilitation

Question 31

39) Why do moderate levels of disturbance result in an increase in community diversity?

Answer 31

A) Habitats are opened up for less competitive species

Question 32

In a particular case of secondary succession, three species of wild grass all invaded a field.
By the second season, a single species dominated the field. A possible factor in this secondary
succession was _____.

Answer 32

inhibition

Question 33

) In the figure above, where do we find the highest species richness?

Answer 33

Communities 2 and 4

Question 34

In the figure above, which community has the highest species diversity?

Answer 34

Community 2

Question 35

In the figure above, what can be stated about species diversity and latitude?

Answer 35

) As latitude increases, diversity decreases.

Question 36

Which of the following statements regarding the figure above is true?

Answer 36

Species richness should be higher on larger islands close to mainland

Question 37

According to the figure above, a species has the highest chance of extinction when _____.

Answer 37

the island is small and remote

Question 38

magine five forest communities, each with one hundred individuals distributed among four
different tree species (W, X, Y, and Z). Which forest community would be most diverse?

Answer 38

25W, 25X, 25Y, 25Z

Question 39

Species richness increases _____.

Answer 39

as we travel southward from the North Pole

Question 40

There are more species in tropical areas than in places more distant from the equator. This is
probably a result of _____.

Answer 40

more intense annual solar radiation

Question 41

Which of the following is a widely supported explanation for the tendency of tropical
communities to have greater species diversity than temperate or polar communities?

Answer 41

Tropical communities are generally older than temperate and polar communities