3.1 What Is Ecology?

Understand Key Concepts

1. All of life on Earth exists in

   1. an ecosystem.

   2. a biome.

   3. the biosphere.

   4. ecology.

2. Which term describes a group of different species that live together in a defined area?

   1. a population

   2. a community

   3. an ecosystem

   4. a biosphere

3. Name the different levels of organization within the biosphere, from smallest to largest.

4. How do ecologists use modeling?

5. Give an example of how a biotic factor might influence the organisms in an ecosystem.

Think Critically

6. Design an Experiment Ecologists have discovered that the seeds of many plants that grow in forests cannot germinate unless they have been exposed to fire. Design an experiment to test whether a particular plant has seeds with this requirement. Include your hypothesis statement, a description of control and experimental groups, and an outline of your procedure.

7. Pose Questions You live near a pond that you have observed for years. One year you notice the water is choked with a massive overgrowth of green algae. What are some of the questions you might have about this unusual growth?

3.2 Energy, Producers, and Consumers

Understand Key Concepts

8. Primary producers are organisms that

   1. rely on other organisms for their energy and food supply.

   2. consume plant and animal remains and other dead matter.

   3. use energy they take in from the environment to convert inorganic molecoles into complex organic molecules.

   4. obtain energy by eating only plants.

9. Which of the following organisms is a decomposer?

   1. 

   2. 

   3. 

   4. 

10. Which of the following describes how ALL consumers get their energy?

    1. directly from the sun

    2. from eating primary producers

    3. from inorganic chemicals like hydrogen sulfide

    4. from eating organisms that are living or were once living

11. What is chemosynthesis?

Think Critically

12. Classify Classify each of the following as an herbivore, a carnivore, an omnivore, or a detritivore: earthworm, bear, cow, snail, owl, human.

13. Form a Hypothesis People who explore caves where there is running water but no sunlight often find them populated with unique types of fishes and insects. What hypothesis can you make to explain the ultimate source of energy for these organisms?

3.3 Energy Flow in Ecosystems

Understand Key Concepts

14. The series of steps in which a large fish eats a small fish that has eaten algae is a

    1. food web.

    2. food chain.

    3. pyramid of numbers.

    4. pyramid of biomass.

15. The total amount of living tissue at each trophic level in an ecosystem can be shown in a(n)

    1. energy pyramid.

    2. pyramid of numbers.

    3. biomass pyramid.

    4. biogeochemical cycle.