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End Show Slide 1 of 41 Copyright Pearson Prentice Hall 3–2 Energy, Producers, and Consumers
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Slide 1 of 41
Copyright Pearson Prentice Hall
3–2 Energy, Producers, and Consumers
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3–2 Energy Flow
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Copyright Pearson Prentice Hall
Producers
Producers
Without a constant input of energy, living systems cannot function.
Sunlight is the main energy source for life on Earth.
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3–2 Energy Flow
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Copyright Pearson Prentice Hall
Producers
In a few ecosystems, some organisms obtain energy from a source other than sunlight.
Some types of organisms rely on the energy stored in inorganic chemical compounds.
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3–2 Energy Flow
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Copyright Pearson Prentice Hall
Producers
Only plants, some algae, and certain bacteria can capture energy from sunlight or chemicals and convert it into forms that living cells can use.
These organisms are called autotrophs.
Autotrophs use energy from the environment to produce “food” by assembling simple inorganic compounds into complex organic molecules. Autotrophs not only feed themselves but store energy and provide it to other organisms that eat them.
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3–2 Energy Flow
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Producers
They are called primary producers becausethey are the first producers of energy-richcompounds that are later used by otherorganisms.
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3–2 Energy Flow
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Copyright Pearson Prentice Hall
Producers
Energy From the Sun
The best-known autotrophs harness solar energy through a process known as photosynthesis.
During photosynthesis, these autotrophs use light energy to convert carbon dioxide and water into oxygen and energy-rich carbohydrates.
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3–2 Energy Flow
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Producers
Photosynthesis is responsible for adding oxygen to—and removing carbon dioxide from—Earth's atmosphere.
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3–2 Energy Flow
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Copyright Pearson Prentice Hall
Producers
Plants are the main autotrophs on land.
Algae are the main autotrophs in freshwater ecosystems and in the upper layers of the ocean
Photosynthetic bacteria are important in certain wet ecosystems such as tidal flats and salt marshes.
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3–2 Energy Flow
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Producers
Life Without Light
Some autotrophs can produce food in the absence of light.
When organisms use chemical energy to produce carbohydrates, the process is called chemosynthesis.
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3–2 Energy Flow
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Producers
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3–2 Energy Flow
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Copyright Pearson Prentice Hall
Producers
Chemosynthesis is performed by several types of bacteria.
These bacteria represent a large proportion of living autotrophs.
Some chemosynthetic bacteria live in very remote places on Earth, such as volcanic vents on the deep-ocean floor and hot springs.
Others live in more common places, such as tidal marshes along the coast.
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3–2 Energy Flow
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Copyright Pearson Prentice Hall
Consumers
Consumers
Many organisms cannot harness energy directly from the physical environment.
Organisms that rely on other organisms for their energy and nutrients are called heterotrophs.
Heterotrophs are also called consumers.
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3–2 Energy Flow
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Copyright Pearson Prentice Hall
Consumers
Consumers are classified by the ways in which they acquire energy and nutrients.
• Herbivores eat plants.
• Carnivores kill and eat other animals.
• Omnivores eat both plants and animals.
• Detritivores feed on plant and animal remains (detritus) and other dead matter.
Types of Consumers
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• Scavengers are animals that consume the carcasses of other animals that have been killed by predators or have died of other causes.
• Decomposers, like bacteria and fungi, break down organic matter.
Copyright Pearson Prentice Hall
Types of Consumers (cont.)
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3–2 Energy Flow
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Beyond Consumer Categories
Categorizing consumers is important, but thesesimple categories often don’t express the realcomplexity of nature.
For example, herbivores that eat different plant parts often differ greatly in the ways they obtainand digest their food.
In addition, organisms in nature often do not stayinside the categories we put them in.
For example, some carnivores will scavenge ifthey get the chance. Many aquatic animals eat amixture of algae, bits of animal carcasses, anddetritus particles.
