Carbon Fixing Adaptations Flashcards
Summary of “C3” plants
- Plants that grow in average cool to warm conditions
- CO2 is fixed in the Calvin cycle via rubisco
What happens to plants in hot, dry environments?
- Plants tend to close their stomata to prevent water-loss through transpiration
- This results in less or very little CO2 fixation and a build up of O2 inside the leaf
Photorespiration
Process by which plants revert to a different form of respiration rather than photosynthesis
Why does photorespiration happen?
Because oxygen is high and carbon dioxide is low in the plant cells
What does “C3” refer to?
- To the 3 carbon (PGA or G3P) intermediate molecule that eventually forms glucose
Examples of C3 plants
- Kentucky bluegrass
- Tomatoes
- Rice
- Barley
- Wheat
- Soybean
- Potatoes
Advantages of C3 plants
- Thrive at medium to low temps
- (up to 25 degrees average)
Disadvantages of C3 plants
- When temps are high CO2 lowers and photorespiration occurs
- Decreases productivity
What are C4 plants also called?
- Floridian plants
- Tropical plants
Summary of C4 plants
- CO2 is fixed twice in two different types of cells
What are the 2 types of cells that fix CO2 in C4 plants?
- Mesophyll Cells
- Bundle Sheath Cells with Chloroplasts
First carbon fixation in C4 plants
- CO2 is attached to PEP which turns into oxaloacetate which is a 4 carbon molecule
Second carbon fixation in C4 plants
- CO2 is released into the bundle sheath cells where typical Calvin cycle occurs
Examples of C4 plants
- Crabgrass
- Corn
- Many tropical shrubs
Advantages of C4 plants
- Plants can have smaller stomata and they don’t need to be open as long
- Water loss is lower and photorespiration does not occur
- More productive
Disadvantages of C4 plants
- Not good in cold temps
- It takes extra ATP to move CO2 around
Summary of CAM plants
- Flourish in deserts
- Only open their stomata at night
- Light reactions occur during the day making NADPH and ATP, which is carried over into the night when the Calvin Cycle occurs
What would happen if CAM plants opened their stomata during the day?
They would become completely dehydrated from the dry desert conditions
Examples of CAM plants
- Cacti
- Pineapples
- Ice plants (succulents)
- Other plants that live in desert and dry environments
Advantages of CAM plants
- Conserve water in the hot dry day
- Photorespiration does not need to occur
- Have evolved thick flesh and deep roots to store both H2O and CO2
Disadvantages of CAM plants
- Cannot live in moist or very cool environments
- Undergo water logging and will rot
