Download Ch 8 - Photosynthesis

Chapter 8 – Photosynthesis
1. Energy for life processes:
sun (light energy)
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Photosynthesis (by autotrophs) makes glucose
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Respiration (by autotrophs and heterotrophs) makes ATP
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Cell activities
2. How ATP (adenosine triphosphate) works:
Break off the 3rd phosphate to release energy
Replace the 3rd phosphate to store energy
3. Photosynthesis equation:
(glucose)
4. Pigment – a chemical that absorbs certain colors of light and reflects others
Chlorophyll a and chlorophyll b absorb red, blue, and violet. They reflect green.
5. Photosynthesis has 2 parts, both occur in the chloroplast.
Light reactions – in the thylakoid
Dark reactions (Calvin Cycle) - in the stroma
Structure of the chloroplast:
Grana - look like stacks of coins. Each individual coin is a thylakoid.
Stroma – space between the thylakoids
6. Light reactions – in the thylakoid, 4 steps
a. Chlorophyll absorbs light, kicks out an electron
b. The electron goes through the electron transport chain, turning NADP+ into NADPH
c. Water molecules are split:
Electrons replace those lost by chlorophyll
Oxygen is released
H+ is used in the next step
d. H+ is used to turn ADP into ATP
Summary: Used: H20, ADP, NADP+
Made: O2, ATP, NADPH
ATP and NADPH move to the stroma to be used in the dark reactions
7. Dark Reactions – also called the Calvin Cycle, occur in the stroma
Uses: CO2, ATP, NADPH
Makes: glucose, ADP, NADP+
ADP and NADP+ move into the thylakoid to be used in the light reactions
The cycle must turn 6 times to make 1 glucose (C6H12O6 )
8. Factors that affect the rate of photosynthesis:
amount of light
temperature
amount of water
9. Stomata:
-Small pores on the underside of leaves
-Closed to prevent water loss when it is hot and dry
-CO2 enters and O2 leaves through the stomata
10. Photosynthesis and climate change (global warming)
- Climate change is caused by an increase of CO2 in the atmosphere
- Since plants take in CO2, destroying forests increases climate change
Problems caused by climate change include:
1. When the ocean warms, ocean currents are changed. This changes weather patterns, creating more
severe storms and increasing desert areas.
2. Oceans become more acidic as they absorb CO2 from the atmosphere. This is bleaching and killing
coral reefs worldwide. (reefs are extremely diverse and important ecosystems)