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Science Olympiad – Ecology
Examination #1
1. a. Use the information below to create a Forest Food Web and select one Food
Chain to make an Energy Pyramid.
Producers – Fern, Oak Tree, Honeysuckle, Grass, Flowers
First Order Consumers – Mouse, Cricket, Moose, Butterfly, Hummingbird, Woodpecker
Second Order Consumers – Frog, Skunk, Owl, Fox
Third Order Consumers – Bear, Cougar, Hawk
Detritivores – Nematodes, Bacteria, Fungi
Forest Food Web
Any arrangement is acceptable, as long as the arrows are pointing in the correct direction (from
the producers to first order consumers, first order consumer to second order consumers, etc.), and
as long as the relationships make logical sense (i.e., the frog IS NOT eating a moose). And
remember that the detritivores have no connection to the overall web.
Food Chain
Any combination is acceptable, as long as the arrows are pointing in the correct direction (as
indicated above).
Example:
Flower  Hummingbird  Owl  Hawk
Energy Pyramid
b. If the producer in your energy pyramid were given 42,750 Joules of energy from the sun,
what amount of energy would the first order consumer have left after it ate and processed
the producer? What about the second order consumer? And the third order consumer?
Please label next to the name of the organism on the energy pyramid, the amount of energy
available to that organism.
2. Compare mutualism, commensalism, and parasitism, and give an example of each.
Mutualism – both organisms benefit
ex. bee and flower
Commensalism – one organism benefits but the other is not hurt/harmed
ex. green algae on a turtle shell
Parasitism – one organism benefits while the other is harmed but not killed
ex. fleas on a dog
3. What are the two abiotic factors that cause differences between biomes?
Temperature and precipitation
4. Name three differences between r-selected and K-selected organisms, and give one
example of each type of organism.
r-selected
- rapid growth
- large-scale reproduction
- occupy unpredictable environments
K-selected
-slow growth
-low-scale reproduction
-occupy stable environments
ex. mice, dandelions, ants, fish
ex. humans, elephants, deer, flamingos
5.
a. What is the independent variable for this graph? How is it measured?
I know we never really went in depth on graph reading during our study sessions, so I am
hoping that you both have had some experience in your science classes with this. The
independent variable is almost always TIME, and the way it is measured is in years. The
independent variable is always on the x-axis.
b. What is the dependent variable for this graph? How is it measured?
The dependent variable is organisms, measured by number of wolves and moose. The
dependent variable is always on the y-axis.
c. When was the wolf population at its greatest? How many wolves were alive that
year?
This answer can be determined by simply reading the graph. The population was at its
greatest in 1980 and there were 53 wolves alive that year.
d. When was the moose population at its greatest? How many moose were alive that
year?
Again, reading the graph will give you this answer. The moose population was at its
greatest in 1993 and there were approximately 1700 moose alive that year.
6. How is it possible for several different species of finches (a species of bird) to live, eat,
breed, and coexist in the very same pine tree, at the same time of year, without running out
of resources?
This is only possible because each of these species of finch has its own unique niche, and
therefore does not use the same resources as the other species (i.e. different types of food,
different places to nest on the pine, and different areas to roost). If they all existed in the same
niche, there would not be enough resources to go around.
7. Explain the role a keystone species plays in a community.
A keystone species is an organism that has a larger effect on the ecosystem than other species in
that same ecosystem, and without that keystone species, the ecosystem would be harmfully
affected. A good example of a keystone species is a beaver. Beavers build dams that form
habitat for fish and other aquatic organisms, while also taking down trees in the forest that are
dead and ready to be decomposed. Thus, beavers not only help keep nutrients flowing in the
ecosystem, they also create habitat for other organism, certainly a rather large job for just one
organism.
8. Describe the process of primary succession and why it is different than secondary
succession.
Primary succession occurs after a natural event that leaves an area with little to no topsoil.
Pioneer species such as moss and lichen are the first to move into the environment. Once they
die and begin to form the first layer of soil, smaller plants and shrubs are able to take root,
further weakening the rock and adding more nutrients to the system. These new plants draw
animals, which add to the diversity and inflow of nutrients. Eventually enough soil is built up
that trees and larger plants may be supported, as can larger animals.
Secondary succession is different because soil still remains after the disturbance, as does root
structure and some seeds.