photosynthesis. the big picture scientists discovered that in the presence of light, plants...
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Photosynthesis
THE BIG PICTURE
Scientists discovered that in the
presence of light, plants transform CO2 and water
into carbohydrates and release oxygen.
_____________ + ____________ _______________ + ____________
Carbondioxide
WATER Sugars Oxygen
6 CO2_____________ + ____________ _______________ + ____________6 H2O C6H12O6 6 O2→
PHOTOSYNTHESIS: Reactants & Products
LIGHT ENERGY
6CO2 + 6H2O SUGAR + 6O2
In addition to water and carbon dioxide,
__________________
and
__________________
are needed for photosynthesis to happen.
chlorophyll
light energy
Because light is a form of ___________, any molecule that absorbs light also ___________the energy from the light.
ENERGY
ABSORBS
Pigments
• Chlorophyll A is the most important photosynthetic pigment.
• The pigments are embedded in the membranes of the chloroplast in groups called photosystems.
Chlorophyll a
Chlorophyll b
Absorption of Light byChlorophyll a and Chlorophyll b
SO WHAT WAVELENGTHS ARE BEST FOR PHOTOSYNTHESIS?
THE ONESCHLOROPHYLLABSORBS THE BEST________ and_______________
red
Blue-violet
Chlorophyll a
Chlorophyll b
Absorption of Light byChlorophyll a and Chlorophyll b
NEITHER KIND OF CHLOROPHYLL IS VERY GOOD AT ABSORBING _________ LIGHT!GREEN
That’s why leaves LOOK GREEN…..
Chlorophyll doesn’t absorb…. it ___________ GREEN light!REFLECTS
PHOTOSYNTHESIS OVERVIEW
Photosynthesis: The Chemical Process
• Occurs in two main phases.– Light reactions– Dark reactions (aka – the Calvin Cycle)
• Light reactions are the “photo” part of photosynthesis. Light is absorbed by pigments.
• Dark reactions are the “synthesis” part of photosynthesis. Trapped energy from the sun is converted to the chemical energy of sugars.
PHOTOSYNTHESIS
Light-Dependent
Reaction
Light-IndependentReactions
CALVIN CYCLE
Light & Water
Oxygen
ATP
NADPH
Carbon Dioxide (CH2O)n
Factors that Affect Photosynthesis____________________
Water is one of the raw materials needed, so
A shortage of water can ________________
photosynthesis
AMOUNT OF WATER
Desert plants and conifers that live in dry conditions have a waxy coating on their leaves to prevent water loss.
slow or stop
Factors that Affect Photosynthesis
Photosynthesis enzymes function best between 0° C - 35° C
At temperatures above or below this
range, photosynthesis will slow or stop
Conifers in winter may carry outphotosynthesis only occasionally
TEMPERATURE
http://www.sustland.umn.edu/maint/images/evergreen10.jpg
Factors that Affect Photosynthesis
____________________
More light increases rate of photosynthesis
up to a certain level until plant reaches its
maximum rate of photosynthesis
LIGHT INTENSITY
THE BIG PICTURE
These experiments led to work by later
scientists who finally discovered that in the
presence of light, plants transform CO2 and water
into carbohydrates and release oxygen.
_____________ + ____________ _______________ + ____________
Carbondioxide
WATER Sugars Oxygen
6 CO2_____________ + ____________ _______________ + ____________6 H2O C6H12O6 6 O2→
•Photosynthesis is the process by which plants and few other organisms use to transform light energy into chemical energy.
•Plants use chlorophyll to collect the energy from the sun rays to create the food they need, the food we eat, the oxygen we, all living creatures need to breath, and fossil fuels, like coal, oil and gas that the industrialized world needs.
•Without this process, life on earth would end, and the only organisms left would be the chemosynthesis bacteria.
•Photosynthesis is basic in the maintenance of life on earth.
THE BIG PICTUREWhy Should You Care?