Cycles of Nature

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Cycles of Nature
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Energy isnt the only thing that flows through
the trophic levels.

• Matter in the form of nutrients also flow
  throughout the trophic levels and biomes.
• The flow of this matter is known as cycles.
• The reason that we use the term cycles is that
  matter in the universe is neither created nor
  destroyed it merely changes form. ( conservation
  of matter and energy)

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Each step through which energy is transferred in
a food chain is known as a TROPHIC LEVEL. Each
time energy is transferred from a producer to a
primary consumer to a secondary consumer energy
is lost as heat and less energy is available to
organisms at the next level.
Biomes is a large area characterized by a
specific type of climate determined by
precipitation (ppt) and temperature AND a
certain type of plant or animal community.
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Different types of cycles

• There are many different types of cycles in
  nature.
• The three that are particularly important to 7th
  grade Environmental Studies are
• The water cycle
• The carbon cycle
• The nitrogen cycle

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The Water Cycle

• Life on Earth depends on water.
• Even before there was life on earth, water cycled
  through stages.
• Plants use water to produce food through the
  process of photosynthesis.
• Heterotrophs use water in almost every life
  process throughout their entire life.

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Four Steps of the Water Cycle

• Evaporation is the change of a liquid to water
  vapor (gas).

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Four Steps of the Water Cycle

• Condensation is the change of water vapor (gas)
  to a liquid.

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Four Steps of the Water Cycle

• Precipitation is any atmospheric water vapor that
  falls to the Earth.
• Rain
• Freezing rain
• Snow
• Sleet
• Hail

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Four Steps of the Water Cycle

• Transpiration is the evaporation of water from
  parts of plants, especially leaves but also
  stems, flowers and roots.

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Where is the Carbon?

• The atmosphere carbon dioxide gas is one form of
  carbon in the air.

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Where is the Carbon?

• Photosynthesis- Autotrophs use carbon dioxide in
  photosynthesis. In photosynthesis, the suns
  energy is used to make high-energy carbon
  molecules.

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Where is the Carbon?

• Wastes- Autotrophs and heterotrophs break down
  the high-energy carbon molecules for energy.
  Carbon dioxide is released as a waste.

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Where is the Carbon?

• Organisms- use high-energy carbon molecules for
  growth. A large amount of the worlds carbon is
  contained in living things.

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Where is the Carbon?

• Soil- When organisms die and decay, the carbon
  molecules in them enter the soil. Microorganisms
  break down the molecules, releasing carbon
  dioxide.

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Where is the Carbon?

• Fuel- Over millions of years, the remains of dead
  organisms are converted into fossil fuels, such
  as coal, gas, and oil. These fuels contain carbon
  molecules.

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Where is the Carbon?

• Pollution- combustion of fossil fuels and wood
  releases carbon dioxide.

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The Nitrogen Cycle

• Nitrogen makes up about 78 of our atmosphere.
  (N2)
• It is not usable to humans and animals in this
  form however, it takes lightning and certain
  bacteria to convert nitrogen into a usable form.
• Plants use the nitrogen to make important
  molecules such as proteins. (fertilizers)
• Herbivores eat plants and convert
  nitrogen-containing plant proteins into
  nitrogen-containing animal proteins.

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The Nitrogen Cycle

• Decomposers break down urine, an animal waste
  which contains excess nitrogen.
• When an animal urinates, nitrogen returns to the
  water or soil.
• When organisms die. Their nitrogen molecules
  return to the soil. Plants reuse these nitrogen
  molecules.
• Nitrogen Fixing Bacteria also act on these
  molecules and put nitrogen back into the air.

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