1. C3 Plants C4 Plants CAM Plants Heterotrophic Plants
PLANT ADAPTATIONS
C3 Plants
C4 Plants
CAM Plants
Heterotrophic Plants

2. PLANT EVOLUTIONARY HISTORY
Life began in water
The first plants were aquatic
When plants moved to land, they had a difficult time dealing with dehydration  this lead to many adaptations that reduced transpiration and preserved water.
Stomata are necessary for gas exchange, but increase transpiration rates. (Trade-offs)

3. C3 PLANTS  most plants
Fix carbon by attaching CO2 to RuBP using the Calvin Cycle
On hot days, they close their stomata part way (which limits sugar production, but minimizes water loss)

4. PHOTORESPIRATION…nooo
PHOTORESPIRATION…nooo! - a process that occurs in the light; consumes oxygen and releases CO2
When a C3 plant uses up the CO2, Rubisco will “fix” or take in O2 and send it to the Calvin Cycle instead of CO2
This process DECREASES the production of glucose – since there is no carbon to make sugars.
Photorespiration uses up the ATP  a wasteful process!

5. So why would any plant do this??
Photorespiration may be an evolutionary “leftover”
In the early atmosphere with little to no oxygen, it didn’t matter if Rubisco had an affinity for O2
Today, with so much O2 in the atmosphere, it is inevitable that some O2 will be fixed instead of CO2
C3 crop plants include Rice, Wheat, Soybeans.
- They may lose as much as 50% of the carbon fixed in the Calvin cycle to photorespiration

6. C4 PLANTS and CAM PLANTS Solution?
Both types of plants have evolved adaptations For alternate methods of carbon fixation in hot, arid climates.
Their stomata stay closed during the day and open at night.
This limits water loss but it also limits the CO2 that diffuses into the leaf for photosynthesis.
Solution?
They store CO2 (in organic acid form) for later use!
Uses PEP Carboxylase before the Calvin cycle to make organic acids

7. C4 PLANTS
These plants “fix”CO2 to a molecule called PEP (phosphoenolpyruvate), using an enzyme called PEP carboxylase, into a an organic acid
PEP has a high affinity for CO2 and none for O2
The organic acid molecule later releases CO2 from PEP and the Calvin Cycle continues as normal.
This adaptation allows C4 plants to keep a high concentration of CO2 – and prevents photorespiration!
C4 examples: sugarcane, corn, and tropical grasses
They thrive in hot climates where their stomata will be closed often.

8. CAM PLANTS
CAM plants keep stomata closed during the day to minimize water loss; they only open at night
This means no CO2 can enter during the day!
CAM plants take in CO2 at night and fix it into organic molecules  this is referred to as Crassulacean Acid Metabolism
CAM plant examples: pineapple, agave, succulent plants
CAM adaptations loses the least water and has the lowest amount of photorespiration compared to C3 and C4 plants

9. HETEROTROPHIC PLANTS Carnivorous Plants Parasitic Plants (Parasites)
These plants live in environments that require adaptations which allows them to supplement their nutrition and minerals (especially nitrogen)
Parasitic Plants (Parasites)
These harm their host by siphoning nutrients and minerals from it. (The parasite fuses their xylem with the host!)
Carnivorous Plants
These plants “eat” insects and other nitrogen rich organisms.
- They typically live in acidic environments that have low nitrogen in the soil due to low decomposition rates.
VENUS FLY TRAP

10. Examples of Parasitic Plants: Examples of Carnivorous Plants:
PITCHER PLANT
MISTLETOE
DODDER