APES
Nitrogen Cycle (Chap. 3 & 10)
Name____________________________________
Period 3 5 8 Date__________ Score_________
Nitrogen Cycle Practice Problems
Preview Challenge: The APES Examination will require you to do mathematical calculations. Occasionally these
calculations may be somewhat esoteric, and you may find it possible to do them in your head; nonetheless, it is
mandatory to show all work for all calculations on the free-response section of the APES exam. This worksheet is
designed help to prepare you for the type of calculations you may encounter on this year’s APES exam.
Show every step of your work, and indicate the cancellation of all units…No Calculators!!
A. Place the following numbers into scientific notation.
1. one billion ________________________________________________________________
2. twenty three thousand _______________________________________________________
3. 70 trillion _________________________________________________________________
4. three hundred _____________________________________________________________
B.
Do the following calculations in scientific notation.
5. five hundred billion times thirty five thousand ______________________________________
6. six thousand divided by 300 billion _______________________________________________
7. one ten thousandth of three million _______________________________________________
8. 6 billion divided by 35 trillion _____________________________________________________
C. Practice Conversions:
9. If there are 0.4 hectares in 1 acre, how many hectares is 10 acres?
10. There are 640 acres in a square mile. How do you solve this: A 100 square mile area of national
forest is how many acres? How many are hectares?
D.
Practice Problems:
Conversions: 1 acre = 0.4 hectare
1 ton = 2000 lbs.
1. Problem: A recommended application rate is 125 lbs. (57 kg) of Nitrogen per acre (0.4 hectare) for
a cornfield. One ton (2000 lbs.; 900 kg) of pig manure contains 14 lbs. (6.4 kg) of nitrogen. Use kg
for your conversion.
a. How many tons of manure must be applied to achieve the recommended rate of nitrogen
application on one acre (hectare)?
57 kg N x ________ = _______ tons
1 acre
1 acre
b. How much fertilizer must be applied on an average 300 acre (120-hectare) corn farm?
2. If a typical one acre (0.4 hectare) of corn that is receiving the recommended application rate loses
4.2 lbs. (1.9 kg) of nitrogen to runoff, what percentage of the application is lost in runoff?
3. How many tons of nitrogen will potentially become runoff from the 300-acre corn farm?
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4. If 35% of a natural area is to be developed, leaving 500 acres untouched, how many acres
are to be developed?
5. Calculate the percentage growth rate for a country with a population of 6 million: in a year
in which it had 100,000 births, 70,000 deaths, 30,000 immigrants, and 50,000 emigrants.
6.
If the concentration of mercury in a water supply changes from 65 ppm to 7 ppm in a tenyear period, what is the percentage change of the mercury concentration?