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WorksheetsKeystone Species and Trophic Cascades
Total questions: 20
Worksheet time: 10mins
What was the primary question the ecologists sought to answer with his starfish experiment?
How do predators influence the structure of ecosystems?
How do starfish reproduce?
What determines the population size of starfish?
What was the apex predator in the ecosystem?
The original hypothesis of food chains was
the green hypothesis
the bottom up hypothesis
energy flow hypothesis
Keystone hypothesis
What was the unexpected result of removing starfish from the ecosystem?
starfish population increased
number of species decreased
the ecosystem was unchanged
number of species increased
What term did Robert Paine coin to describe the influence of a single species on an ecosystem?
Apex predator
Dominant species
Keystone species
Primary species
What was the main finding of the ecologists research on sea otters?
Sea otters are primary producers
Sea otters have little to no impact on the ecosystem
Sea otters indirectly controlled the sea urchins
Sea otters directly controlled the sea urchins
What happened to the kelp forest when the sea otters were removed?
Kelp forests became more diverse
Kelp forests disappeared
Kelp forests thrived
Kelp forests were unchanged
What do ecologists call the effect of one species affecting multiple levels in a food chain?
direct
indirect
no effect
neutral effect
What did ecologists call the effect of one species on multiple levels of a food chain?
Trophic cascade
Food chain reaction
direct effect
Keystone effect
What broader implication does the study of keystone species and trophic cascades have for ecology?
It indicates that predators have no significant role in ecosystems
It shows that all species have equal impact on ecosystems
It highlights the importance of top down regulation in ecosystems
It suggests that ecosystems are primarily controlled by the producers
What is the role of keystone species in an ecosystem?
They have no effect on the ecosystem
They have a disproportionately large effect on the abundance and number of species
They are the most abundant species
They are always apex predators.
Fill in the blank: Not all species in an ecosystem have strong interactions. The removal of some species has ______ effect on others.
a large
a little or no
a moderate
a significant
Which of the following statements is true about apex predators?
They are always preyed upon by others
They are at the top of a food web and are not preyed on by others
They have no effect on the ecosystem
They are the most numerous species.
Keystone species are critical to maintaining what in an ecosystem?
The number of predators
The diversity and stability
The amount of sunlight
The water levels
What happens when a keystone species is removed from an ecosystem?
Nothing changes
Only the keystone species is affected
It causes changes in the type and number of species
The ecosystem becomes more stable.
Fill in the blank: Many keystone species are ______ predators.
secondary
apex
primary
tertiary
Which of the following is NOT a characteristic of keystone species?
A) They have a large effect on their ecosystem
B) They are always the most numerous species
C) They can be apex predators
D) They help maintain ecosystem stability.
What is required to understand how species numbers and population sizes are regulated in an ecosystem?
Short-term observations
Experiments conducted over long time periods
Immediate assumptions
Quick surveys
Fill in the blank: The removal of some species has little or no effect on others because not all species have ______ interactions.
strong
weak
temporary
permanent
What is the risk of ignoring the role of apex predators in ecosystems?
Ecosystems will remain stable
The prey of predators will increase
Ecosystems would gain diversity
It could lead to significant changes in an ecosystem
The keystone species of yellowstone is which of the following?
Elk
Grizzly bears
Wolves
Black bears
