Populations unit test
A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.
Overshoot and dieback
Replacement level fertility
Logistic growth equation
Why Stage 2 grows fastest
Calculating percent growth rate
r-selected species
Population growth rate calculation
Crude birth and death rates
Demographic transition
Total fertility rate
Net migration rate
Infant mortality rate
Short answer 1. Define or explain: Rule of 70
3 ptsShort answer 2. Define or explain: Why replacement fertility is 2.1, not 2.0
3 ptsShort answer 3. Define or explain: Survivorship curves
3 ptsShort answer 4. Define or explain: Biotic potential
3 ptsFree response
10 ptsThis course has no free-response prompt tagged to this unit, so one from elsewhere in the course is used. It is still worth writing — the skill transfers.
DESIGN AN INVESTIGATION. A shallow freshwater lake bordered by farmland has developed dense algal blooms each summer for the past several years. Farmers apply nitrogen and phosphorus fertilizer to fields that drain into the lake through a network of ditches. A group of students hypothesizes that phosphorus in the runoff is the nutrient limiting algal growth in this lake, and they want to test that hypothesis before recommending any change in farm practice. The students have access to lake water, laboratory beakers, a light bank, a supply of nitrogen fertilizer solution, a supply of phosphorus fertilizer solution, and a device that measures the concentration of chlorophyll in a water sample.
A(i). Identify the hypothesis the students are testing. A(ii). Identify the independent variable in an experiment designed to test it. A(iii). Identify the dependent variable.
B(i). Describe a control group appropriate for this investigation. B(ii). Describe two variables that should be held constant across all treatments.
C. Describe the results the students would expect to observe if their hypothesis is correct.
D. Explain why a laboratory experiment using beakers may not accurately predict what happens in the lake itself.
E. Identify one environmental consequence of the algal bloom for organisms living in the lake, and explain the mechanism that produces it.
F. Describe one agricultural practice that would reduce nutrient runoff from the surrounding fields, and explain how it works.