Directions: For each statement write true or false in the blank.
______1. An organism’s niche includes its habitat.
______2. Trophic levels describe the differences in size of the organisms in a
habitat.
______3. Carnivores obtain nutrients by eating other consumers.
______4. Organisms that feed on dead organisms are called scavengers.
______5. Humans are classified as carnivores.
______6. All of the energy available to organisms at each level of the food
chain is stored.
______7. A food chain is the specific sequence in which organisms obtain
energy in an ecosystem.
______8. Food chains usually consist of eight or nine levels.
Directions: Determine if the statement is true. If it is not, rewrite the underlinded part to make it true.
______9. Biology means the study of interactions among organisms.
______10. Sunlight and temperature can be biotic factors for a particular organism.
______11. Autotrophs make their own energy.
______12. If you are studying a population of squirrels, then you are studying a community.
______13. A predator is an animal that gets eaten by other animal.
______14. Parasitism is type of symbiosis in which both organisms benefit from the relationship.
______15. Primary succession occurs on surfaces where no soil exists.

Directions: For each statement below, decide whether it relates to the nitrogen cycle, carbon cycle, oxygen cycle, water cycle, or all of the cycles. Write “N” for nitrogen, “C” for carbon, “W” for water, and “A” for all.
_______16. This is a biogeochemical cycle.
_______17. Plants make proteins and nucleic acids from ammonia.
_______18. Evaporation, transpiration, condensation, and precipitation are involved.
_______19. Living organisms incorporate into their bodies substances that are
returned to the environment when they die.
_______20. The burning of fossil fuels has changed the normal balance in this cycle.
_______21. Photosynthesis and cellular respiration are involved in this cycle.
Directions: The statements below describe the secondary succession that occurred within an area of Yellowstone National Park. Number the events in the order in which they occurred.
______22. Grasses, ferns, and pine seedlings inhabited the area.
______23. Annual wildflowers grew from the bare soil.
______24. A fire burned thousands of acres of land.
______25. A climax community of lodge pole pines developed.
______26. Bare soil covered the area.
Directions: Choose that one best response. Write the letter of that choice in the space provided.
______27. A food chain generally begins with:
A. autotroph B. omnivore C. decomposer D. heterotroph
______28. Interrelated food chains are called a:
A. food niche B. food web C. habitat D. food chain
______29. Which group of organisms is responsible for releasing nutrients back
into the ecosystem so that the nutrients may be recycled by
producers?
A. insects B. bacteria C. mammals D. phytoplankton
______30. The greatest amount of energy in an ecosystem is available to:
A. producers B. primary consumers
C. secondary consumers D. decomposers

______31. What percent of energy is stored at each trophic level of an ecosystem?
A. 100% B. 50% C. 10% D. 5%
______32. Besides energy, what moves through the organisms at each trophic
level of an ecosystem?
A. organisms B. nutrients C. sunlight
______33. What organism drives the nitrogen cycle?
A. plants
C. animals
B. fungi
D. bacteria
D. cycles
______34. What do plants use in photosynthesis to make carbon molecules?
A. carbon dioxide
C. nitrogen gas
B. carbohydrates
D. oxygen
______35. Heterotrophs get carbon molecules by
A. growing B. feeding on other organisms
C. decaying D. making the molecules themselves
Directions: Answer the following questions completely using the picture of primary succession on the next page.
36. What do ecologists mean by the term succession?
37. How is secondary succession different from primary succession?
38. Explain the process of primary succession as illustrated in the picture.
39. What is a climax community, and which organisms in the picture represent
this type of community?
40. Based on the picture, if you hiked through a patch of land that contained a
pine forest into an area that contained only ferns, shrubs, and grasses, would
you be moving from an older to a younger community or vice versa? Explain.
41. Which parts of the ecosystem had to be established before the primary
succession shown in the picture could occur?