A partial food web for organisms in Yellowstone National Park is shown below.
1. Assume the elk population in Yellowstone National Park increases. Discuss how this
increase in elk will most likely affect each population listed below. Be sure to include
specific reasons to support each of your responses.

Idaho fescue: Decrease due to increased # of elk grazing on fescue.

Migratory grasshopper: Decrease due to increased competition with elk
for limited food.

Grizzly bear: Could increase due to more elk for bears to feed on;
however, more elk might mean less grasshoppers/chipmunks and
marmots which could leave the bear population unchanged or even
decreasing
Base your answers to the next 3 questions on the diagram below and on your knowledge of
ecology. The diagram represents a food web.
2. Identify two herbivores that compete for food in the food web above.
____deer___mice
grasshoppers_________________________________________
3. Even though both hawks and owls have 2 food sources, explain why hawks would be less
likely to survive if a disease wiped out the mice.
The hawks' other food source is snakes which feed on the mice, so an less mice will also
mean less snakes.
4. State the role of decomposers in this food web.
Decomposers break down material, return nutrients to soil, and recycle matter.
5. Describe the niche of an oak tree. Include at 3 specific roles in your answer.
 Photosynthesis by oak trees provides food & oxygen to organisms.
 Shelter for organisms like squirrels, birds, etc.
 Transpiration by oak trees returns water to atmophere.
 Shade affects the types of organisms that like under an oak tree.