APES: Making Connections for the Midterm
1. Distinguish between an open system and a closed system. Compare the flow of matter and the flow of energy
through the biosphere.
2. Five “spheres” make up the biosphere; atmosphere, troposphere, stratosphere, hydrosphere, and lithosphere.
What is significant/important about each one – describe it!
3. Define abiotic and biotic components of an ecosystem. For one of each, describe how it acts as a limiting factor
on a population.
4. Draw a trophic level pyramid with the following terms below. Write a definition/example for each next to your
pyramid. = Autotrophs, Primary Consumers, Secondary Consumers, Tertiary Consumers, Omnivores,
Detritivores, Scavengers, Decomposers
5. Describe the difference between Gross Primary Productivity (GPP), and net primary productivity (NPP). What
does the planet’s NPP limit? Why are there so few tertiary consumers in your pyramid?
6. Explain how predator and prey populations depend on each other
7. Explain why this statement is true: "A human vegetarian's ecological footprint is smaller than a meat-eater's
footprint."
8. What is a keystone species and what happens to an ecosystem when it gets removed? Identify a keystone
species for each biome.
9. Distinguish between weather and climate.
10. What are the two most important factors that will determine the type of climate in a region? Pick three biomes
and discuss their differences/similarities between these factors. * “Factors that affect climate” flashcards can be
found online.
11. Describe how differences in climate lead to formation of tropical, temperate, and polar deserts, grasslands, and
forests.
12. Define oceanic currents and explain how they, along with global air circulation, support the formation of
different biomes.
13. Describe the “Tragedy of the Commons”. Give one example.
14. How does poverty affect human population growth? Give two examples of how poverty and human population
growth have a negative effect on the environment.
15. Contrast positive and negative feedback loops. Give an example of each for the human population. Give an
example of each for soil conservation/degradation.
16. Describe what makes a resource renewable, nonrenewable, and/or perpetual. Compare total resource use per
capita in developed and developing countries.
17. The figures below show the age structures of human populations in three countries, X, Y, and Z. Which of these
three countries has the largest rate of population growth? Which has the smallest? (Explain). Compare infant
mortality rates that are likely in Countries X and Y. Explain your reasoning.
18. Describe the changes in both the birth rate and death rate for a country making the transition from a
preindustrial society to an industrial society.
Math Practice
1. If the earth’s population is approximately 7 billion currently, how long will it take to double in size if the
population growth maintains at 2%?
2. If the GDP of the U.S. is $15,000,000,000,000, and the population is about 300,000,000, what is the GDP per
capita?
3. If the U.S. population is about 300,000,000, and each person has an ecological footprint of about 10 hectares,
what is the total ecological footprint for the U.S. in hectares?
4. If 1 hectare = 0.01 km2, what is the area of the ecological footprint of the U.S. in km2?
5. If Asia’s birth rate is 19 per 1,000 people and its death rate is 7 per 1,000 people, what is its growth rate in
percent?
6. How much does it cost to heat a 3,000 square foot house in Virginia for the winter, assuming 50,000 BTUs of
heat per square foot are required to heat the house for the winter. One cubic foot of natural gas supplies 1,000
BTUs of heat energy. Natural gas is available at a cost of $4.00 per thousand cubic feet.
a. What if the system was only 50% efficient?
7. Estimate the potential reduction in petroleum consumption (gallons of gasoline per year) that could be achieved
in the United States by introducing electric vehicles under the following assumptions:
 The mileage rate for the average car is 20 miles per gallon of gasoline.
 The average car is driven 15,000 miles per year.
 The United States has 200 million cars.
 Twenty percent of the US cars could be replaced with electric cars.
8. Between 1966 and 2012, the global human population increased from 3.5 billion to 7.0 billion. Global poultry
production increased from 35 billion kilograms to 84 billion kilograms during this period.
a. Calculate the per capita poultry production in 1966 and in 2012.
b. The average chicken breast has a mass of 0.40kg and provides 350 kcal. How many kcal of energy were
available from the poultry production in 1966.
c. Assuming we only got 10% of the kcals that the chicken took in, how many joules of energy did the
chickens start with in 1966? (Remember: 1 kcal = 4,184 J)