Yellowstone Wolves and Trophic Cascades
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| Source:Wikipedia History of Wolves in Yellowstone |
I came across this video through Facebook and thought it was so good for a TOEFL subject and so fascinating too, that I decided to make a little listening exercise out of it.
This time, I will give you multiple choice questions which makes it closer to the TOEFL exam, in particular, the PBT.As in the TOEFL exam, look at the questions as you listen - ignore the visuals until after you have done the questions, then watch again and enjoy the images! It is such a lovely, feel-good video!
Click on the link to the video here:
Yellowstone wolvesHere are the questions:
1. What is this talk mainly about?A The damage to Yellowstone caused by wolves
B The changes attributed to wolves to the ecosystem and physical geography of Yellowstone
C The animals that live in Yellowstone
D The habitats of all the different species in Yellowstone
2. A trophic cascade is
A a high waterfall
B the flow of rivers through a valley
C an ecological process starting at the top of the food chain and going to the bottom
D an ecological process to describe the change to the plains
3. The reintroduction of wolves to Yellowstone in 1995 caused
A the deer population to increase in number
B the decline in the number of beavers
C the vegetation to grow back and the number of different species to increase
D more soil erosion
4. The rivers have become less ________ and the banks more __________
A polluted:unstable
B straight:rocky
C deep:steep
D meandering:stable
