HHMI Exploring Trophic Cascades

What is the definition of an ecosystem?

• A group of animals of the same species living in the same place.

• All the plants and animals living in the same place.

• All organisms living in the same place and the abiotic factors that affect them.

Which of the following is not a biotic factor in an ecosystem?

• wind

• algae

• dead skunk

• oak tree

Which of the following would be included in a system?

• inputs and outputs

• boundaries

• interactions

• components

Tags

NGSS.MS-LS1-3

NGSS.MS-LS2-3

In this ecosystem model, what is missing?

• plants

• the top predator

• abiotic factors

• consumers

Tags

NGSS.MS-LS2-2

NGSS.MS-LS2-3

In the mid 1900's, the wolves of Yellowstone were deeply affected by humans and their population significantly decreased-- making them endangered, and eventually removing them completely from the Yellowstone ecosystem. The removal of wolves, the top predator, caused what to happen to the biodiversity within Yellowstone?

• A trophic cascade affected the entire food web in Yellowstone, causing some organisms to experience decreases, and others to grow rapidly.

• Biodiversity increased when the wolves disappeared and more species were able to flourish without the wolves.

• A trophic cascade irreversibly ruined the ecosystem in Yellowstone--destroying biodiversity forever.

• The biodiversity of the park was not affected when the wolves were removed.

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-2

NGSS.MS-LS2-3

NGSS.MS-LS2-4

Which of the following is true of the included graphs?

• The reintroduction of wolves led to a decline in the beaver population.

• The reintroduction of wolves led to an increase in the elk population.

• The ecosystem was healthier after wolves were reintroduced.

• The reintroduction of wolves led to a decline in the bison population.

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-2

NGSS.MS-LS2-4

How did the kelp forest ecosystem change after sea otters were removed?

• sea urchin population increased

• the kelp population decreased

• sea stars increased because there were more sea urchins to eat

• the phytoplankton population decreased

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-2

NGSS.MS-LS2-4

The trophic cascade in Yellowstone had many causes and affects. Which answer below most accurately shows the changes in the ecosystem due to the reintroduction of wolves?

• wolves reintroduced-> deer population increased -> tree and vegetation cover decreased

• wolves reintroduced-> beaver population decreased -> tree and vegetation cover increased

• wolves reintroduced-> deer population decreased -> tree and vegetation cover increased -> beaver population increased

• wolves reintroduced-> deer population decreased -> beaver population decreased -> songbird population increased

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-2

NGSS.MS-LS2-3

NGSS.MS-LS2-4