MCA Test Preparation
Part 2
#1:
26 Points Total
2/2 = 1 pt.
#2:
3/3 = 1 pt.
+
+
+
#3. (1 pt.) Where zebra mussels are present, the carrying capacities of native mussel
population in lake ecosystems are most likely…
a) Decreased
b) Eliminated
c) Increased
d) Unchanged
#4: (1 pt.)
+
#5. (1 pt.) Zebra mussels filter plankton and other matter from lake and river water.
What are 2 likely results of this filtration?
a) Decreased plankton populations and decreased water clarity.
b) Increased plankton populations and increased water clarity.
c) Decreased plankton populations and increased water clarity.
d) Increased plankton populations and decreased water clarity.
#6. (2 pts.) Describe the long-term impact that an invasive species such as
zebra mussels may likely have on lake ecosystems.
“Zebra mussels could out-compete native species in the ecosystem and
lead to extinctions. This could upset the natural balance in lakes.”
2/2: The student correctly describes the long-term impact invasive species such
as zebra mussels will have on lake ecosystems. Two examples include outcompeting native species and filtering too much food out of the water.
1/2: Student gives an incomplete description of the long-term impact invasive
species such as zebra mussels will have on lake ecosystems
#7. (2 pts.) Questions about zebra mussels…
a) Type a question about zebra mussels that is better approached through a
controlled laboratory experiment than through a field investigation.
• “One question that may be answered through a controlled experiment
is, “How much salt can zebra mussels tolerate?”
b) Explain why your question is better approached through a controlled
experiment.
• “This question is best answered in a laboratory experiment because
salinity conditions can be controlled better in a laboratory than in a
natural environment.”
2/2: The student correctly identifies a question that would best be answered by a
controlled laboratory experiment and explains why that question is best
approached through controlled experimentation. Explanations should recognize
that controlled experimentation is superior to field observation.
1/2: The student correctly identifies a question that would best be answered by a
controlled laboratory experiment but fails to explain why that question is best
approached through controlled experimentation.
#8. (1 pt.) Which of these questions can be answered by performing tests on
the water samples collected by the students?
a) How deep is the lake?
b) What is the fish population in the lake?
c) What pollutants are present in the lake?
d) In what direction does water flow through the lake?
#9. Write the name of the 3 objects into the diagram to show how carbon
flows through an ecosystem.
3/3 = 1 pt.
#10. (1 pt.) What is the ultimate energy source for the organisms in this lake
ecosystem?
+
#11. (2 pts.) For each trophic level, write
the name of 1 organism from the food web
into the appropriate box.
Producers & Consumers = +2
Producer Only = +1
Consumers Only = +1
Producer
Primary Cons.
Sec. Cons.
Tertiary Cons.
Algae
Zooplankton
Aquatic Inverts
Duck
Aquatic Plants
Aquatic Inverts
Small Fish
Big Fish
Duck
Duck
Heron
Insects
Bird
#12. (1 pt.) Mr. Lang’s students made 4 statements as they conducted research at
the lake. Which statement is quantitative?
a)
b)
c)
d)
“The phosphorus level in the lake is high.”
“The algae population is growing rapidly.”
“The lake water looks much greener today than last time.”
“The phosphorus level in the lake has risen 3 micrograms per liter (ug/L).”
#13. (1 pt.) Which calculation best describes the
changes in lake-water phosphorus levels?
a) Total micrograms per liter on August 1
b) Percent increase from May 1 to August 1
c) Average micrograms per liter of all 4
dates
d) Difference between phosphorus and
chlorophyll levels on August 1
#14. (1 pt.) Assuming that phosphorus levels influence chlorophyll levels,
how would chlorophyll levels change over time if the people in surrounding
areas gradually stopped fertilizing their fields and lawns with phosphorus?
Plot 3 points (“+”) to show the trend in chlorophyll levels.
Downward trend = 1 pt.
+
+
+
#15. (3 pts.) The students observe that as the phosphorus level increases, the
amount of algae in the lake also increases. However, they are not sure that
the increase in phosphorus is the cause of the increased amount of algae.
Describe a simple experiment to demonstrate that an increase in phosphorus
causes an increase in algae growth.
“In a lab, take 5 – 50 ml beakers and place them under the same strength
lights and fill each beaker with 30 ml of water taken from the same lake.
Then add 1 ml of algae to each beaker and let it sit for a day. Then the next
day add ½ a ml of phosphorus to the first beaker, 1 ml to the second beaker,
and 1 ½ ml to the third beaker, 2 ml to the forth beaker, and 2 ½ ml to the fifth
beaker. Then let the beakers sit for a week. Take the beakers and filter out
the water to measure the amount of algae grown. If the 5th beaker has the
most, then we know that phosphorus is a reason for algae growth.”
3/3: A simple experiment is described that demonstrates that an increase in phosphorus causes an
increase in algae growth. The experiment must include…
•2 or more samples
•Only 1 manipulated variable
•At least 1 controlled variable (Example – Initial algae, Light, Time, Temp., or amount of water
•At least 1 responding variable that would show an increase in algae.
2/3: 3 of 4 Criteria
1/3: 2 of 4 Criteria
#16. (3 pts.) You will be listing 3 organisms in this ecosystem that would be
affected if a local extinction of the zooplankton occurred.
a) List 1 organism in the ecosystem that would be affected if a local
extinction of the zooplankton occurred. Explain what would likely
happen to the population and why this change would occur.
“Small fish would be affected if the zooplankton became extinct. The
probable effect on the population would be a dramatic decrease
because the small fish no longer have a food source, thus many
would starve and competition between the fish would greatly
increase”
b) List a second organism in the ecosystem that would be affected if a
local extinction of the zooplankton occurred. Explain what would
likely happen to the population and why this change would occur.
“Algae would also be affected by the extinction of zooplankton, and
the population of it would most likely greatly increase because the
zooplankton is responsible for eating the algae”
c) List a third organism in the ecosystem that would be affected if
a local extinction of the zooplankton occurred. Explain what
would likely happen to the population and why this change
would occur.
“The heron population in this region would be likely to
decrease because the herons depend on small fish for
food, which depend on the zooplankton. After the
decrease in small fish because of their lack of food the
heron would also suffer a loss of food supply.”
3/3: Student lists 3 organisms and accurately explains what
would happen to each organism and why this change to the
organism would occur.
2/3: 2 organisms explained
1/3: 1 organism explained
#17. Decomposers in an ecosystem…
a) Explain why decomposers are important in maintaining the flow of nutrients
through an ecosystem.
“Decomposers break down nutrients and put them back in the soil so plants
can continue to get the nutrients they need to grow and survive. Animals
and other organisms get the nutrients they need from the plants they eat.
Without decomposers, plants would not be able to get their needed
nutrients, and neither would anything higher up on the food chain.”
a) Predict what would happen if decomposers were removed from an ecosystem.
“If decomposers were removed, dead organisms could not be broken down
into nutrients. Waste would not be broken down and the ecosystem would
become overfilled with waste. Plants would not be able to get their needed
nutrients from the soil which would also cause the animals higher up on the
food chain to not get their needed nutrients. Eventually the ecosystem
would fail, and everything in it would die.”
3/3: Student clearly and completely explains that decomposers are
important in returning nutrients to an ecosystem and making them
available to other organisms by explaining that…
•Decomposers break down dead organisms and waste
•Decomposers return important nutrients to the soil and make
them available for other organisms
AND
•The student clearly makes a reasonable prediction of what would
happen if decomposers were removed from the ecosystem.
2/3: 2 of key points
1/3: 1 of key points
26 Total Points