A partial food web from Yellowstone National Park is shown below.
Based on the food web, which would have a greater impact on the ecosystem: a disease that kills off all the gray wolves, or overhunting that removes all of the buffalo population?
Based on the diagram to the left, what effect did the removal of bull sharks have on the stability and biodiversity of the coral reef ecosystem?
When key organisms are added or removed from an ecosystem, they can trigger what is known as a trophic cascade. Think of this like the domino effect: a change at one level of the food chain causes a ripple effect, impacting organisms at other levels of the food chain.
Using the diagram above, explain how the removal of the wolf triggered a trophic cascade that affected the tree population.
The diagram below shows a food web before and after starfish were removed from a tidal pool on the Northwestern coast of the United States.
How has the removal of starfish affected the ecosystem?
Gray Wolves, Bull Sharks, and Starfish are all considered the keystone species of their ecosystems. In your own words, what do you think a keystone species is?
Which of the following best describes the role of a keystone species in an ecosystem?
After the removal of wolves from Yellowstone National Park, scientists observed a dramatic increase in elk populations. This led to overgrazing of willow and aspen trees, reducing habitat for beavers and songbirds. When wolves were reintroduced, the ecosystem began to recover.
Based on this scenario, which of the following best explains the role of wolves as a keystone species?
In a coastal ecosystem, sea otters prey on sea urchins, which consume kelp. After sea otter populations decline due to hunting, scientists notice that kelp forests begin to disappear.
Which of the following is the most likely outcome if sea otters are permanently removed?
In the African savanna, elephants play a crucial role in maintaining the ecosystem by knocking down trees, which prevents forests from overtaking grasslands. This allows grass-eating species such as zebras and antelope to thrive. Due to poaching and habitat loss, elephant populations are decreasing.
What is the most likely consequence of the declining elephant population in this ecosystem?
A scientist removes Pisaster starfish from a rocky intertidal ecosystem and observes a rapid increase in mussel populations. Over time, mussels outcompete other species, reducing biodiversity.
What does this experiment suggest about the role of Pisaster starfish?
Jaguars are apex predators in the Amazon rainforest, preying on various herbivores such as capybaras and deer. If jaguar populations decline due to habitat loss, what is the most likely consequence?
A species of fast-growing vine is introduced to a forested region where it has no natural predators. The vine quickly spreads, covering trees and preventing them from receiving sunlight. Over time, tree populations decline, affecting animals that rely on them for food and shelter.
Why is this vine considered an invasive species?
A wetland ecosystem is home to alligators, which dig holes that fill with water during dry seasons. These holes provide a critical water source for fish, birds, and mammals. However, a new species of aggressive freshwater fish is introduced into the wetland, rapidly consuming smaller native fish and disrupting the food web.
How do the roles of alligators and the invasive fish differ in this ecosystem?
The food web shows the flow of energy in a desert ecosystem.
What effect would the removal of the mountain lion have on the ecosystem?
Part of a benthic marine food web is shown in the diagram below.
What would happen if overfishing drastically reduced the Galatheid Crab population?
Below is a diagram of a Meadow Food Web.
What would happen if foxes were removed from the ecosystem due to overhunting?
Below is a diagram of a Meadow Food Web.
Which populations would increase if the snake population was removed from this ecosystem?
A food chain from the meadow food web is shown below.
Which of the following choices best represents how much energy is available to each trophic level in the food chain?
A biomass pyramid of an ecosystem is shown.
Which statement provides the best explanation for the difference in biomass of organisms found at each trophic level?
The food chain below represents one interaction from a swamp food web.
Which of the following choices best represents how much energy is available to each trophic level in the food chain?
What would happen to this ecosystem if all of the birds disappeared?
The diagram below shows a partial food web.
Which table correctly classifies these organisms?
The Green Peach Aphid is a highly invasive insect that causes decreased growth, shriveled leaves, and the death of various tissues in peach trees. They also spread various plant viruses which can spread to other plants and vital crops. To control an outbreak of invasive aphids, a farmer releases two species of non-native ladybugs in addition to a species of native ladybugs into his field.
Which of the following is a potential unintended negative consequence of releasing these three species of ladybugs into the environment?
Plastic waste from a nearby city has led to a blockage in a river, causing water levels in a wetland to drop significantly. This has exposed large areas of mudflats, reducing aquatic plant populations from lack of water.
Which description best explains how plastic pollution from humans could affect the wetland ecosystem?
In the 1990s, ranchers on Maggie Creek in Nevada moved the areas where their cattle were grazing. This move was done to help vegetation regrow on the banks of the creek, which had been eroding due to lack of vegetation.
After the move, vegetation began to return to the creek banks. The graph below shows the changes in the amount of green vegetation from 1985 to 2016.
Evaluate the impact of human actions with the Maggie Creek ecosystem.
The pileated woodpecker, Dryocopus pileatus, is a medium sized bird with a bright red crest. The D. pileatus is found in most of New-England forests, where they look for insects within the tree bark.
Which human activity would most likely decrease the ability of the birds to survive?
Large swaths of Florida are made up of marsh lands, a type of wetland that is home to many organisms, including alligators, turtles, blue herons, and otters. As cities expand, they fill the marsh with concrete in order to have more residential land, this leads to habitat loss for these animals.
Which of the following is the most likely consequence of this environmental change?
In 1884 wolves were considered incredibly dangerous, so Montana placed a bounty on wolves. This led to a large quantity of wolves being hunted, causing the wolf population to drop. These wolves were the only organism that could eat deer in this habitat.
How would the human impact of hunting most likely affect the food web?
Below is a food chain from an Arctic ecosystem:
Drag the correct organisms to the correct spot on the pyramid.
The Hoover Dam was built in 1936, blocking the Colorado River, one of the largest rivers in the USA. The Dam was made to create energy and to control floods, but there were many unintended consequences on the environment, what is a negative consequence of the Hoover Dam?
