PHOTOSYNTHESIS

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PHOTOSYNTHESISRespiration
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I. Introduction to photosynthesis

• From the Greek
• PHOTO produced by light
• SYNTHESIS a whole made of parts put
  together.
• Definition PHOTOSYNTHESIS is the process
  whereby plants, algae, some bacteria, use the
  energy of the sun to synthesize organic compounds
  (sugars) from inorganic compounds (CO2 and water).

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WHY IS PHOTOSYNTHESIS SO IMPORTANT?

• PHOTOSYNTHESIS is one of the most important
  biological process on earth!
• Provides the oxygen we breathe
• Consumes much of the CO2
• Food
• Energy

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GENERAL FORMULA FOR PHOTOSYNTHESIS

• light
• 6 CO2 12 H2O ---------gt C6H12O6 6 O2 6
  H2O
• pigments, enzymes

• Oxygen on earth allowed for the evolution of
  aerobic respiration and higher life-forms.
• Respiration extracting energy from compounds
  (sugars)
• C6H12O6 O2 ? 6 CO2 ATP

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PROPERTIES OF LIGHTVirtually all life depends on
it!

• Light moves in waves, in energy units called
  PHOTONS

• Energy of a PHOTON inversely proportional
• to its wavelength

• Visible light (between UV and IR) occurs in
• a spectrum of colors

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Visible light contains just the right amount of
energy for biological reactions
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Light is absorbed by pigments

• The primary pigment for photosynthesis is
  chlorophyll a
• It absorbs blue and red light, not green (green
  light is reflected back!)

Absorption spectrum of chlorophyll a
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Where does photosynthesis occur?
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The plant cell
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VI. Summary of Photosynthesis

• Light energy absorbed by chlorophyll a drives the
  reactions of photosynthesis.

2. Converts light energy into chemical energy to
make organic compounds.
3. CO2 and H2O used to produce C6H12O6
(glucose) and O2 (gas).
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Importance of photosynthesis and the impact that
it has in all our lives.Without photosynthesis,
virtually all plants and animals would become
extinct.
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Respiration, Energy Carbon Cycle

• Energy
• Virtually all organisms require energy of food
  for
• Making chemicals (proteins, carbs, etc.)
• Movement
• Cell division
• The way living organisms obtain energy is
  throughCell respiration

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RESPIRATION

• Process of making energy of food available in the
  cell
• Involves breaking down
• Complicated molecules ? into simple molecules
• (C6H12O6, sugars) (CO2, water)

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RESPIRATION

• The energy held by complicated molecules is held
  temporarily as ATP (energy currency)
• C6H12O6 6 O2 ? 6CO2 6 H2O 36 ATP
• (glucose) (energy)

Respiration occurs mainly in Mitochondria and
Cytoplasm
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Photosynthesis Respiration

• Reaction CO2H2Osun?C6H12O6O2H2O
  C6H12O6O2?CO2H2OSun
• Reactants Carbon dioxide, water, sun
  Glucose, oxygen
• Products Glucose Energy
• By-products Oxygen Carbon dioxide, water
• Cellular location Chloroplasts Cytoplasm,
  mitochondria
• Energetics Requires energy Releases energy
• Summary Sugar synthesized using Energy
  released from energy from the sun
  sugar breakdown

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The Carbon Cycle

• Carbon from the atmosphere (CO2) enters the
  biosphere by way of plants!
• CO2 used in photosynthesis
• Carbon moves into food chain
• Carbon is released to the physical environment by
  respiration
• Release CO2 during respiration
• Amount CO2 fixed in photosynthesis the amount
  released by respiration

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Photosynthesis and respiration

• Photosynthesis and respiration are complimentary
  reactions

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Carbon Cycle

• Carbon moves from atmosphere to plants to animals
  and back to atmosphere.

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• Carbon Cycle
• All living organisms are based on Carbon.
• Carbon moves through ocean, living organisms,
  atomosphere, and crust.
• May take millions of years to come full circle.

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Vocabulary

• Sinks-where carbon is stored
• a. Trees, fossil fuels, limestone, rocks
• Sources-where carbon is released
• a. Burning of fossil fuels, respiration,
  weathering of rocks

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Example

• CO2 in atmosphere-absorbed by fern in
  Carboniferous Period.
• Photosynthesis-becomes part of stem.
• Fern dies and gradually covered with other
  organic matter. Carbon trapped in remains.
• Coal bed mined by humans 360 my later
• Burned-reenters atmosphere.

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Fossil Fuels

• Oil
• Coal

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PHOTOSYNTHESIS RESPIRATION

• CO2 H2O ? O2 SUGARS SUGARS O2 ?
  H2O CO2

O2
CO2
O2
CO2
MOST LIVING ORGANISMS
PLANTS, ALGAE, BACTERIA
SUGARS
H2O
H2O
Sunlight energy
USEFUL CHEMICAL ENERGY (ATP)
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ENERGY ability to do work

• Newtons First Law of Thermodynamics
• Energy cannot be created or destroyed, it can
  only be transformed from one form to another
• Once a cell has used energy to do work, it cannot
  be used again by any organism.

(1701)
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ENERGY

• ENERGY FLOW IS LINEAR
• Sun ? Earth ?Producers ?1o consumers ? 2o consum?
• heat resp, heat resp, heat
  resp, heat
• Energy flows into ecosystem from the sun
• Energy travels in a straight line by way of
• food chains.

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ENERGY

• However, much energy is lost as heat along the
  way as a result of respiration.
• Approximately 90 energy is lost on each step!
• Newtons Second Law of
• Thermodynamics
• In any transfer of energy there is always a
  loss of useful energy to the system, usually in
  the form of heat

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Food Chains

• (Not referring to SHOPPERS, SAFEWAY or GIANT !!!)
• Food chains demonstrate linear nature of energy
• Producers are the base of the food chain, they
  include photosynthetic organisms like
• Plants
• Algae
• Certain bacteria

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Food chains

• Primary consumers all plant eaters
  (herbivores).
• Secondary consumers
• Eat primary consumers, (carnivores)

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Food chains

• Decomposers obtain energy by breaking down
  remaining organic material of the other members
  of the food chain.
• Fungi and bacteria.

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Matter

• All important elements move in cycles
• Environment Organisms
• Cycles called biogeochemical cycles
• Water cycle
• Carbon cycle
• Nitrogen cycle

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Look deep into nature, and then you will
understand everything better.
Albert Einstein