4.1 Roles of Living Things

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4.1 Roles of Living Things

• 1. Identify the roles of producers, consumers,
  and decomposers.
• 2. Explain the concept of trophic level.
• 3. Infer why the number of organisms at a given
  trophic level is smaller than in the preceding
  level.

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Roles of Living Things

• The organisms of most ecosystems gather food in
  three basic ways as producers, consumers, or
  decomposers. Energy enters the ecosystem only at
  the level of the producer. All other organisms
  depend on the energy first captured by the
  producers.

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Producers

• Organisms that make their own food from inorganic
  molecules and energy are called producers.
• Plants are the most familiar producers. Almost
  all producers capture energy from the sun and use
  it to make food through photosynthesis. (The
  reactions of photosynthesis use the energy from
  sunlight to combine carbon dioxide and water to
  produce sugars).

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Photosynthesis

• 6H2O 6CO2 ----------gt C6H12O6 6O2
• http//earthguide.ucsd.edu/earthguide/diagrams/pho
  tosynthesis/photosynthesis.html

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Producers

• Plants are the most important producers in
  terrestrial (land) ecosystems.
• In aquatic (water) ecosystems, small
  photosynthetic Protists and bacteria are the most
  important producers.

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Consumers

• Organisms that cannot make their own food are
  called consumers.
• All animals are consumers, as are fungi and many
  Protists and bacteria.
• Consumers obtain energy by eating other
  organisms.

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Consumers

• There are four basic kinds of consumers
• Organisms that eat only plants are called
  herbivores. Because only eat producers,
  scientists call them primary consumers. Many
  insects and birds are herbivores, as are grazing
  animals such as cows, buffalo, and antelope. The
  bodies of herbivores are adapted to gathering,
  grinding, and digesting plants.

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Consumers

• Carnivores capture and eat herbivores or other
  carnivores. Carnivores that eat primary
  consumers are called secondary consumers, and
  those that eat other carnivores are called
  tertiary consumers.
• Lions are carnivores, as are snakes, hawks, and
  spiders.
• The bodies of carnivores are adapted to hunting,
  capturing, and eating prey.

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Consumers

• 3. Some consumers, including human beings, are
  omnivores, eating both producers and consumers.
  (bears and chimpanzees)
• Omnivores act as primary, secondary, or tertiary
  consumers depending on what they eat.
• A person who eats a potato acts as a primary
  consumer.
• If the same person eats a hamburger, however, the
  person acts as a secondary consumer.

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Consumers

• Scavengers usually do not hunt living prey, but
  instead feed on the bodies of dead organisms.
• Scavengers will eat dead plants or feed on the
  bodies of herbivores, carnivores, or anything
  else they find.
• Like omnivores, scavengers act as secondary,
  tertiary, or higher consumers depending on what
  they eat.
• Vultures and hyenas are scavengers, as well as
  many insects.
• Scavengers start the process by which nutrients
  from dead bodies are returned to environment.

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Decomposers

• Bacteria and fungi that consume the bodies of
  dead organisms and other organic wastes are
  called decomposers.
• They consume a variety of dead organic matter,
  from the fallen leaves of a tree to the bodies of
  herbivores and carnivores.
• Bacteria and fungi also break down the organic
  matter in animal waste.
• Decomposers are crucial to the ecosystem because
  they recycle nutrients from organisms back into
  the environment.

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Trophic Levels

• Scientists call the different feeding levels of
  organisms in an ecosystem trophic levels.
  troph meaning to feed or nourish.
• A trophic level is a layer in the structure of
  feeding relationships in an ecosystem.
• Producers make up the first trophic level, and
  consumers make up several more trophic levels.
  Producers are called autotrophs, which are the
  sole point of entry for new energy into the
  ecosystem.
• Consumers called heterotrophs form the second and
  higher trophic levels in the ecosystem.
• Most ecosystems have three, four or five trophic
  levels depending on the levels below it.

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Trophic Level
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Trophic Level
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Trophic Levels
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4.1 Homework

• Many places on the ocean floor are so deep that
  sunlight cannot penetrate. Because there is no
  sunlight in these places, there can be no
  photosynthesis. But the ocean floor still
  supports an ecosystem. How is this possible.