1. A trophic cascade...
...affects wolves.
...finishes on top of the food chain.
...is an ecological process which starts at the top of the food chain and tumbles all the way down to the bottom.

2. The reintroduction of wolves to Yellowstone Park is an example of a trophic cascade.

3. Yellowstone National Park is in...
...the US.
...South America.

4. Wolves were reintroduced in Yellowstone in the...
early 1900s.
mid 1900s.
late 1900s.

5. Wolves kill.... species of animals.
a little

6. Before wolves arrived - they had been absent for 70 years - the number of deer ...
had decreased.
had remained relatively consistent.
had increased year after year.

7. There were so many deer that they greatly reduced the amount of vegetation in the park by....
eating it
fertilizing it
damaging it

8. When wolves arrived, even though they were few in number, they ...
changed the behavior of the deer.
ate the deer.
started to protect the other animals

9. With the arrival of wolves, the deer...
started to stay away from certain parts of the park - the places where they could be trapped most easily.
started going to other places in the park - the valleys and the gorges.
didn't go to the places that started to regenerate.

10. Why did the number of birds increase greatly?
The wolves killed the animals that eat birds.
Since the deer were gone, the birds felt protected.
Since the deer weren't eating the vegetation, the plants and trees grew, which provided habitat for the birds.

11. The number of other species decreased.

12. The number of bears increased.

13. How did the rivers change?
The rivers became cleaner - which is great for wildlife.
The rivers meandered less - which means they curved and bent less often.
The shape of the rivers changed more often - which benefitted the wildlife.

14. Why do they say that wolves changed the rivers?
Because they killed the beavers, so the rivers flowed more rapidly.
Because they scared away the deer, so the forests grew and prevented erosion.