CH 37

Which of these research topics would be considered an example of community ecology?

A researcher found that the reproductive success of bumblebees decreased when the population density of honeybees increased. The decline in the number of bumblebees appeared to be a result of competition for nectar. Submit

If the niches of two species are very similar, which of the following is true?

Competition between the two species will be severe. (Two species with similar needs for the same limited resources cannot coexist in the same place.)

Consider the following prairie food chain. Tall grass is consumed by grasshoppers that, in turn, are eaten by mice, and the mice are eaten by prairie kingsnakes. Red-tailed hawks prey on mice and prairie kingsnakes. When a red-tailed hawk dies, bacteria, beetles, fungi, and many types of worms help break down the body. Which of the following correctly identifies a trophic level in this ecosystem?

Grasshoppers are primary consumers. Grasshoppers consume the producers and are therefore primary consumers.

Without elephants, some of the grasslands in Africa would eventually become thickets or forests because elephants weed out trees and shrubs. Even though elephants make up a small percentage of the animals living on the grassland, the grassland would eventually cease to exist without them. In this community, elephants are __________.

a keystone species. (A keystone species is a species that has a greater impact on the community than would be expected based on its relative abundance or total biomass.)

Ecological succession

a transition in species composition of a community

herbivory (+/-)

an animal consumes plant parts or algae.

mutualism (+/+)

both populations benefit.

Flounder look like the sea floor. This is an example of _____.

camouflage

Humans and sharks both eat fish. Which of these terms applies to the relationship between the human and the shark?

competition

Detritivores

derive their energy from detritus, the dead material produced at all the trophic levels. EXAMPLE: earthworms and millipedes

An earthworm that feeds on the remains of plants and animals is acting as a _____.

detritivore

Scavengers

feed on carcasses left behind EXAMPLE: Vultures or crows

Humans who have pets tend to be healthier than humans who do not have pets. Which of these terms applies to the relationship between a human and a pet?

mutualism

Secondary succession

occurs after a disturbance has destroyed a community but left the soil intact. EXAMPLE: areas that recover from fires and floods

predation (+/-)

one species (the predator) kills and eats another (the prey)

Which of these terms applies to the relationship between a dog and a blood-sucking tick?

parasitism

A human eats a deer. Which of these terms applies to the relationship between the human and the deer?

predation

A cow eating grass is an example of a _____.

primary consumer. By feeding on a producer, the cow is acting as a primary consumer.

In an ecosystem, phytoplankton are _____.

producers

Consider this segment of a food web: Snails and grasshoppers eat pepper plants, spiders eat grasshoppers, shrews eat snails and spiders, owls eat shrews. The shrew occupies the trophic level(s) of __________.

secondary and tertiary consumers. (When shrews eat snails, they are secondary consumers. When shrews eat spiders, they are tertiary consumers.)

When a human eats a steak, the human is acting as a _____.

secondary consumer

Which of the following is an abiotic reservoir? birds soil the fish in the sea an algal bloom

soil This is an abiotic reservoir that is a storage point for many chemicals in between their use in living organisms.

A human who just ate a hamburger is eaten by a shark while swimming. The shark is acting as a _____.

tertiary consumer The shark that ate the human that ate the cow that ate the grass is the tertiary consumer.

Primary succession

the gradual colonization of barren rocks.

parasitism (+/-)

the host plants or animals are victimized by parasites or pathogens.

Interspecific competition occurs when

the niches of two populations overlap and both populations need a resource that is in short supply.