Life Cycles

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Life Cycles

• Mrs. A. Kay

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Sustaining life

• Biotic living part of the environment. Ex
  plants and animals
• Abiotic non-living part of the environment.
  Ex elements, air, and water.

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The Carbon Cycle
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The key events - respiration and photosynthesis

• Photosynthesis takes carbon dioxide, water and
  energy to produce carbohydrates and oxygen.

• Respiration takes carbohydrates and oxygen,
  combines them to produce carbon dioxide, water,
  and energy.

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photosynthesis respiration

• CO2 H2O C6H12O6 O2

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Photosynthesis

• Photosynthesis starts with water present in the
  soil and carbon dioxide from the atmosphere (the
  product of respiration, combustion).
• Chlorophyll is the green pigment in plants (gives
  them their color). This uses the light from the
  sun as the energy needed to transform carbon
  dioxide and water into sugar (made into starch,
  cellulose and lignin).
• Photosynthesis also produces oxygen which the
  plant releases into the atmosphere.

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Respiration

• The cell works constantly to stay alive.
• It constructs macromolecules
• It transports substances into and out of the cell
  
• It moves (some cells)
• It grows
• It reproduces
• To accomplish these tasks and many others, the
  cell needs energy that it must get from its
  environment. We know that the sun is the energy
  for plants and other photosynthetic organisms,
  but what about the consumers?

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• heterotrophes. use organic molecules in their
  food to get the energy they need.
• Respiration uses the sugar in food to make
  energy. The byproducts of respiration are water
  and carbon dioxide.

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Reservoirs for carbon dioxide

• The chief reservoirs for carbon dioxide are the
  oceans and in rock.
• CO2 is soluble in water and can react with
  minerals (Ca) to form rock

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What happens to the Carbon?

• Plants take up carbon dioxide and convert it into
  carbohydrates through photosynthesis.
• This carbon in the plants now has 3 possible
  fates (i) it can be liberated to the atmosphere
  by the plant through respiration (ii) it can be
  eaten by an animal, (iii) it can be present in
  the plant when the plant dies
• Animals obtain all their carbon from their food,
  and, thus, all carbon in biological systems
  ultimately comes from plants (autotrophs). In
  the animal, the carbon has the same 3 possible
  fates as in plants.

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The Carbon Cycle in Action

• Carbon from plants or animals that is released to
  the atmosphere through respiration will either be
  taken up by a plant in photosynthesis or
  dissolved in the oceans.
• When an animal or a plant dies, 2 things can
  happen to the carbon in it. It can either be
  respired by decomposers (and released to the
  atmosphere), or it can be buried intact and
  ultimately form coal, oil, or natural gas (fossil
  fuels).
• Humans have a great impact on the carbon cycle
  because when we burn fossil fuels. This means
  that more carbon dioxide goes into the oceans.
  More is carbon dioxide present in the atmosphere
  which causes global warming,

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Homework

• Read pages 43, 46-47,50.
• Do questions 1-7 on page 51