Photosynthesis Affectors Flashcards
What are 3 things that affect photosynthesis
Light intensity, temperature, co2 concentration
What happens with more light?
Higher rate of photosynthesis
What happens with higher temp?
Rate of photosynthesis raises until reaches 27° then decreases until 40° where completely denatures
What happens with high co2 concentration?
Increases until reaches plateau
What is photorespiration
Plant uses sun to produce co2 instead of o2
Problem if photorespiration
Less sugar and starch are produced and plants have a difficult time surviving
Where does photorespiration happen?
Calvin cycle
What is the worlds most abundant enzyme?
RuBP
RuBP is to plants as what is to humans?
PDC
How did photorespiration start?
Co2 levels used to be much higher but as plants photosynthesized atmosphere filled with oxygen.
Oxygen now competes with co2 for RuBisCo bonding sites
What happens if o2 enters RuBisCO instead of CO2?
Then there isn’t enough carbon to make PGA and sugars are made much slower
What happens as temperature raises with photorespiration
More o2 finds it’s way into RuBisCO
Main plants photorespiration
C3
Solution for c3
Evolved and produced new mechanism called c4
What changed in c4?
Palisade mesophyll cells surround bundle sheath cells
Important enzyme helping with photorespiration
PEP carboxylaze.
Photorespiration fighters
C4 and CAM
Where does CAM exist?
Succulents such as cacti or dessert plants
How do CAM plants resist photorespiration
Same 2 carbon fixing steps as c4 but not separated between mesophyll and bundle sheath instead the carbon dioxide fixing enzymes are in sane cells.
How do CAM PLANTS WORK
Stomata open at night
Co2 diffuses into leaf and mesophyll cellsand foxes by c4 photosynthesis and changed into malic acid and stored in vacuoles until next day
When sun rises stomata closes and malic acid is transported out of vaculoe to cytoplasm
Then broken down and all co2 will enter chloroplast to be continued with closed stomata
