Ecosystems and Energy

Chapter 3

Ecosystems and Energy

I. What is Ecology?

ii.

iii.

iv. A ______and its physical environment comprise an ecosystem

1. An ecosystem is a system in which all of the biological, physical, and chemical components of an area form a complex, interacting network of energy flow and materials cycling

2. Ecosystem processes ______

______

C. Landscape ecology is a subdiscipline of ecology

i. It studies ecological processes that operate over large areas

ii. A ______ is a region that includes several interacting ecosystems

i. The parts of Earth’s atmosphere, ocean, land surface, and soil that contain all living organisms is termed the ______

ii.

iii.

iv.

II. The Energy of Life

A. Energy ______

i. Energy exists in several forms: chemical radiant, thermal, mechanical, nuclear, and electrical

ii. Energy can exist as stored energy (______) or as the energy of motion (______)

B. The study of energy and its transformations is called ______

i. In thermodynamics, the word ______ is used to refer to a group of atoms, molecules, or objects being studied

ii.

iii.

1. The less usable energy is more diffuse, or disorganized; entropy is a measure of this disorder or randomness

2. No process requiring an energy conversion is ever 100% efficient because much of the energy that is dispersed as heat, resulting in an increase in entropy

C. Photosynthesis and cellular respiration

i. Photosynthesis is the biological process in which light energy from the sun is captured and transformed into the chemical energy of carbohydrate (glucose) molecules

2. Equation:

ii. Cellular Respiration -

2. Anaerobic bacteria that live in waterlogged soil, stagnant ponds, or animal intestines ______

D. Chemosynthesis is the ______

______; water and sulfur/sulfate are additional byproducts

III. The Flow of Energy Through Ecosystems

A. Energy flow is the ______

______ecosystem

B. Producers, consumers, and decomposers

i. Producers (aka ______)

1. In photosynthesis, producers ______

______

2. Plants, algae and certain types of bacteria are important producers

ii. Consumers (aka ______)

1. Consumers obtain energy ______producers or other consumers

a. Consumers that eat producers are ______consumers (______)

b. Secondary consumers (______) eat ______consumers

c. ______consumers (top carnivores) ______consumers

2. Omnivores ______

______

3. Detritus feeders (______) consume organic matter that includes ______

______

iii. Decomposers (aka ______)

2. ______and ______are important decomposers.

C. The path of energy flow: ______

in ecosystems

i. In an ecosystem, energy flow occurs in ______, in which energy ______in a sequence

1. Energy enters ecosystems from an ______(the ______), flows linearly, and ______

______.

2. Each level in a food chain is termed a ______

ii. Simple food chains ______occur in nature, a ______

______is a more realistic model

D. Ecological pyramids

i. ______ graphically represent the relative energy values of each ______level

1. A ______of______ show the ______of organisms at each trophic level in a given ecosystem

2. A ______of ______illustrates the total ______at each successive trophic level

a. Biomass –

b. Biomass indicates the ______of ______at a particular time

3. A pyramid of energy illustrates the energy content, often expressed as kilocalories per square meter per year, of the biomass at each trophic level

E. Ecosystem productivity

ii.

1. Only the energy represented by NPP is ______as food for an ecosystem’s consumers

2. Ecosystems differ strikingly in their ______(NPP)

iii. Human impact on NPP

Critical Thinking and Review End of Chapter Questions:

1. Draw a food web containing organisms found in a Chesapeake Bay salt marsh.

2. Describe the science of ecology?

3. Which scientist—a population ecologist or a landscape ecologist—would be most likely to study broad-scale environmental issues and land management problems? Explain your answer.

4. What is energy? How are the following forms of energy significant to organisms in ecosystems: (a) radiant energy, (b) mechanical energy, (c) chemical energy?

5. Give two examples of potential energy, and in each case tell how it is converted to kinetic energy.

6. Is this an example of an open system or a closed system? Explain your answer.

7. How is the first law of thermodynamics related to the movement of an automobile?

8. Give an example of a natural process in which order becomes increasingly disordered.

9. How are photosynthesis and cellular respiration related? Write the overall equation for both processes.

Photosynthesis

Cellular respiration

10. Why is the concept of a food web generally preferred over a food chain?

11. Could you construct a balanced ecosystem that contained only producers and consumers? only consumers and decomposers? only producers and decomposers? Explain the reasons for your answers.

12. Label these parts in the following simple ecosystem: producer, primary consumer, secondary consumer, decomposer. Which of these organisms photosynthesizes? Which carry out cellular respiration? Which give off heat into their surroundings?

13. Suggest a food chain with an inverted pyramid of numbers—that is, greater numbers of organisms at higher than at lower trophic levels.

14. Is it possible to have an inverted pyramid of energy? Why or why not?

15. Relate the pyramid of energy to the second law of thermodynamics.

16. What is NPP? Do humans affect the global NPP? If so, how? If not, why?

17. Alcohol fuels produced from corn are often considered a climate friendly answer to our energy needs. Explain why a large-scale increase in the production of corn to provide fuel could have a negative or even catastrophic impact on ecosystems.

Review Questions

What is Ecology?

1. What is ecology?

2. What is the difference between a community and an ecosystem? Between an ecosystem and a landscape?

The Energy of Life

1. Distinguish among energy, work, and heat.

2. Is water stored behind a dam an example of potential or kinetic energy? What would cause the water to convert to the other form of energy?

3. Is a rabbit an example of a closed system or an open system? Why?

4. When coal is burned in a power plant, only 3% of the energy in the coal is converted into light in a light bulb. What happens to the other 97% of the energy? Explain your answer using the laws of thermodynamics.

5. Distinguish between photosynthesis and cellular respiration. Which organisms perform each process?

The Flow of Energy Through Ecosystems

1. How does energy flow through a food web consisting of producers, consumers, and decomposers?

2. What is a pyramid of energy?

3. What is gross primary productivity? Net primary productivity?