Photosynthesis
Photosynthesis is the process by which autotrophs trap the sun’s solar energy and convert
it to chemical energy that is stored in the carbohydrates or other organic compounds they
make (synthesize). You will see that this process, similar to cellular respiration, requires a
complex series of chemical reactions (biochemical pathways). Autotrophs, being the base of a
trophic level pyramid, are key to ecosystems, not only in supplying biomass for food chains
but also in cycling matter between inorganic and organic forms.
Overview
Energy
 Identify which has more potential energy, organic compounds or carbon dioxide and water.
Explain how you know. Hint: respiration
 Identify for respiration and photosynthesis whether the process is exothermic or endothermic;
recognize energy graphs for each
 Explain how autotrophs, like plants, are able to “capture” sunlight
 Describe how different colors of the light spectrum differ from one another and how this relates
to how plants capture sunlight
Photosynthesis
 Write a balanced chemical equation that summarizes the reactants and products (R & P) of
photosynthesis
 Relate the R & P of photosynthesis to the R & P of
respiration
 Describe the history of the development of
understanding the R & P of photosynthesis
 Describe the structure of a chloroplast; know the
locations of the two major stages of photosynthesis
 Explain the “big idea” of what happens in each
stage
The Stages of Photosynthesis
Light Reactions-Stage I
 Explain the role of light; be specific
 Explain the role of water; be specific
 Describe what occurs in the electron transport chain (ETC)
between photosystem II and I
 Describe what occurs in the ETC following photosystem I
 Explain the importance of making ATP and NADPH from the
light reactions
 Describe how ATP is produced in the light reactions; describe
chemiosmosis
 What molecules, of the overall equation, are used and/or
produced in the light reactions?
 Be able to label a diagram of the light reactions
Calvin cycle-Stage II
 Identify where the carbon comes from for a plant to make sugar (and other organic
compounds); know where carbon fixation takes place
 Describe what happens in the first step of the cycle.
 Describe the events that convert PGA to PGAL
 Explain what happens to the PGAL made in the Calvin cycle (Hint: there are two answers to
this question.)
 How is RuBP regenerated in the cycle?
 What molecules, of the overall equation, are used and/or produced in the Calvin cycle?
 Explain what is meant when the Calvin cycle is described as “light-indepdendent”. Is it truly
independent of light?
 Identify the basic differences between C3, C4, and CAM plants; know why different
“strategies” of carbon fixation evolved in plants
Other concepts
 Describe the results of the photosynthesis lab experiments, and explain the significance of the
color changes
 Identify and/or label the parts of a leaf as viewed under a microscope; give the function of each
tissue layer and type of cell
 Explain how changing the
variables of CO2 concentration,
light intensity, and temperature
would affect the rate of
photosynthesis
 Describe a plant’s role in the
following geochemical cycles:
water, carbon, nitrogen.
 Describe and/or label diagrams of
the carbon or nitrogen cycles.