1. Nutrient Cycles and Energy Flow
CHAPTER 1
In this chapter, you will:
explain that life depends on recycled matter
describe the processes of photosynthesis and cellular respiration
explain how humans can affect the cycles of matter and energy flow in ecosystems
assess the impact of fertilizers on aquatic ecosystems
observe the chemistry of photosynthesis
model acid precipitation
determine the impact of excess fertilizers on plants
Copyright © 2010 McGraw-Hill Ryerson Ltd.

2. Abiotic Characteristics of an Ecosystem
(Page 12)
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3. Abiotic Characteristics of an Ecosystem
(Page 12)
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4. Cycling of Matter and Earth’s Spheres
(Page 13)
Ecological processes move matter from the biotic and abiotic parts of an ecosystem and back again in continuous cycles.
The lithosphere is the hard part of Earth’s surface.
The hydrosphere is all of the water found on Earth (lakes, oceans, and ground water).
The atmosphere is the layers of gas above Earth’s surface.
The biosphere is the regions of Earth where living organisms exist.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

5. Nutrient Cycles: Water
(Page 14)
Nutrients are chemicals that are needed by living things and are continually cycled through ecosystems.
The water cycle moves water through the hydrosphere, atmosphere, and lithosphere. This occurs by way of evaporation, condensation, and precipitation.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

6. Nutrient Cycles: Carbon
(Page 15)
The carbon cycle moves carbon through all of Earth’s spheres. Carbon exists as a gas—carbon dioxide (CO2)—in the atmosphere. This gas is used by plants to make sugars. Sugars are broken down by organisms to release energy and CO2. Carbon is stored in fossil fuels buried within Earth and in carbonate (CO3) rock found in the lithosphere.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

7. Nutrient Cycles: Nitrogen
(Page 16)
The nitrogen cycle moves nitrogen through Earth’s spheres. Nitrogen gas (N2) from the air is converted into ammonium (NH4) and into nitrates (NO3) by bacteria and cyanobacteria.
In terrestrial (land based) ecosystems, ammonium (NH4) is produced by soil bacteria. In aquatic (water based) ecosystems, NH4 is produced by cyanobacteria. Nitrates (NO3) are produced from ammonium.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

8. Nutrient Cycles: Phosphorus
(Page 17)
The phosphorus cycle moves phosphorus from the lithosphere, where it is stored in rocks as phosphate (PO43-), to the hydrosphere by the processes of leaching and run-off. Plants then use the phosphorus.
The phosphates in plants and animals are released back into the soil by bacterial decomposition.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

9. Click the “Start” buttons to review the various nutrient cycles.
Nutrient Cycle Review
Click the “Start” buttons to review the various nutrient cycles.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

10. Human Activities and Nutrient Cycles
(Page 18)
Aquatic ecosystems suffer when run-off contains high amounts of agricultural fertilizers (which are high in nitrates and phosphates). The added nutrients can lead to the eutrophication of bodies of water.
Eutrophication is a process in which nutrient levels in aquatic ecosystems increase, leading to an increase in the populations of primary producers, such as algae.
Eutrophication eventually leads to a reduction in the oxygen content of the water.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

11. Cycling of Matter and Earth’s Spheres
(Page 19)
Learning Check 2
5. What is eutrophication? 6. Which nutrient was found to be the main cause of eutrophication in northern Ontario lakes? 7. What is one possible source of excess phosphorus in aquatic ecosystems? 8. Suppose that you have a small fishpond in your backyard. You work hard to get your lawn looking thick and green. By the end of the summer, your lawn looks great, but the water in your fishpond is green and the fish are dead. What might have happened?
Copyright © 2010 McGraw-Hill Ryerson Ltd.