Species richness isThe number of organisms in a communityThe total weight, or biomass, of living organisms in a given areaThe...

Species richness is

1.  The number of organisms in a community
2.  The total weight, or biomass, of living organisms in a given area
3.  The number of species in a population
4.  The number of different species in an area

Question 2Select all that apply.10 pointsWhich of the following are examples of symbiosis? Select all that apply.

1.  Head lice complete an entire life cycle within a person’s hair and scalp; they cannot survive long away from a human host.
2.  Deer range widely feeding on many different types of grasses, herbs, and woody plants.
3.  Bees feed on flower nectar and pollen; in the process they move pollen from one flower to the next and help plants mate.
4.  Archaea (prokaryotes) live in the guts of ruminants like cattle; they help cattle digest plant fibers and in return are provided with a warm place to live and abundant food.
5.  Bark beetles live, feed, and breed within the soft wood just beneath the bark of their host trees. They leave the tree only for a brief time as adults.

Question 3Select one answer.10 pointsIn Africa, grasses are the main vegetation in savanna communities. Acacias and other trees are few and widely scattered. Elephants range over very large territories and are not very abundant in any one location. However, they strongly affect the community by uprooting and consuming trees and shrubs, maintaining suitable habitat for grasses and grassland animals. Many species of birds and insects live in the savanna grasses. Based on this information, which of the species or groups above would best be described as keystone species?

1.  birds and insects
2.  grasses
3.  acacia trees
4.  elephants

Question 4Select one answer.10 pointsThe effect of wolves on the survival and growth of young trees along rivers in Yellowstone National Park is a good example of...

1.  predation.
2.  an indirect interaction between two species.
3.  symbiosis.
4.  a direct interspecific interaction.

Question 5Select one answer.10 pointsOccasionally American alligators are sighted in rivers or lakes in New York City, far north of their usual range. These alligators are usually escaped pets. There is no self-sustaining population of alligators in New York, and they have no important influence on other populations there. Is the American alligator a member of the ecological community in New York?

1.  No
2.  Yes

Question 6Select one answer.10 pointsWhich of the following is an indirect interspecific interaction?

1.  Big fish eat small fish.
2.  Zooplankton eat (graze) floating algae called phytoplankton.
3.  Individual pike (large fish) compete with each other for feeding territories.
4.  Large fish reduce the abundance of phytoplankton. This occurs because large fish eat small fish, which leads to greater zooplankton numbers. The zooplankton grazing then reduces phytoplankton abundance.
5.  Small fish eat swimming crustaceans called zooplankton.

Question 7Select one answer.10 pointsWhich of the following would probably have a greater richness of native plant species per acre?

1.  old, healthy forest
2.  a polluted and heavily disturbed lot in an industrial park

Question 8Select one answer.10 pointsIn Africa, grasses are the main vegetation in savanna communities. Acacias and other trees are few and widely scattered. Elephants range over very large territories and are not very abundant in any one location. However, they strongly affect the community by uprooting and consuming trees and shrubs, maintaining suitable habitat for grasses and grassland animals. Many species of birds and insects live in the savanna grasses. Which of the species or groups above would best be described as foundation species?

1.  grasses
2.  birds and insects
3.  elephants
4.  acacia trees

Question 9Select one answer.10 pointsWhich of the following is a direct interspecific interaction?

1.  Individual lions compete with each other for food and mates.
2.  Through their effects on antelope behavior, lions increase the survival of some plant species.
3.  Lions eat antelope; in the presence of lions the antelope population is reduced.
4.  Hormones circulating within a lion affect her levels of hunger and motivation to hunt.

Question 10Select one answer.10 pointsWhich of the following is known to be a keystone species in the kelp forest ecosystem?

1.  Urchins
2.  Sea otters
3.  Kelp