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Introduction to Photosynthesis
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Objectives Discuss energy flow through living systems
Identify the parts of a leaf Outline the process of photosynthesis
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Overview Plants convert the energy of sunlight into the energy of chemical bonds of carbohydrates
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Importance of Photosynthesis
Provides energy for plants Provides energy for animals that eat plants Provides energy for animals that eat animals that ate plants Provides energy for organisms that break down all of the above Provides the energy for most ecosystems on earth
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But that’s not all.. Gives us food
Provides wood, paper, other wood based products Provides cotton, hemp, other fibers Is the original source of energy in coal and oil Plants are pretty
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Photosynthesis consumes Carbon Dioxide
But wait, there’s more.. Photosynthesis consumes Carbon Dioxide And Produces Oxygen
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History Jan Van Helmont
Found the mass of a pot of soil and a seedling. Watered the seedling for five years. Found the mass again Concluded that the increase in mass came from water
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History Joseph Priestly
Found that a candle goes out when placed in a jar. However, the candle keeps burning if a sprig of mint is also placed in the jar. Concluded that plants produce [Oxygen]
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History Jan Ingenhousz
Showed that Priestley’s experiment only works in the light. Concludes that light is necessary for plants to produce oxygen
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History Magic School Bus class
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Chemical basis of photosynthesis
CO2+H C(H2O)+O2 Light
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Balanced Equation Light 6CO2+6H C6H12O6+6O2
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CO2+H20 C(H2O)+ O2 Sun Entropy Photosynthesis Respiration
The BIG Picture
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Leaf Structure – p.655
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Leaf structure
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Requirements for Photosynthesis
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Light Mostly violet, blue and red wavelengths from the visible spectrum
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Chlorophyll (a and b) – green
Pigments Substances that absorb certain wavelengths of light and reflect other wavelengths Thus they are colored Examples: Chlorophyll (a and b) – green Carotene – red/orange Xanthophylls - yellow
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Energy Storing Compounds
Energy trapped by molecules can be used to lift electrons to a higher energy level. From that higher energy level the electrons can fall down to their original energy level and do work along the way. Example – a solar cell that powers a calculator
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Or… The high-energy electrons can be bound to an electron carrier.
Nicotinamide Adenine Dinucleotide Phosphate NADP+ accepts a pair of high energy electrons and a Hydrogen ion to become NADPH
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Energetics ATP – Adenosine Triphosphate
Energy storing compound used by every living cell Energy harvested via the light reaction is stored in ATP and used to convert CO2 into sugar by using the H obtained from splitting water.
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Function of ATP ATP If the cell need energy it breaks ATP into ADP+P
If the cell has energy to store it makes ATP
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Overview of Photosynthesis
Light reactions Dark reactions – Calvin Cycle
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Light Reactions Energy from sunlight is trapped,
water molecules are split, NADPH and ATP are formed, O2 is given off as a waste gas
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Calvin Cycle Products from the light reactions and CO2 from the atmosphere are used to produce carbohydrates
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Objectives Discuss energy flow through living systems
Identify the parts of a leaf Outline the process of photosynthesis
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Homework See planner.
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Have a nice day
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