Lecture 4 - C4 Photosynthesis Flashcards
pls
What’s a mesophyll cell
Standard plant leaf cell with chloroplast
What’s a bundle sheath?
Specialised plant cell around vascular bundles, has chloroplasts
How does CO2 leave leaf in C4 photosyntehsis
It diffuses into air space and eventually into mesophyll cells
What happens to CO2 in Mesophyll cells
CO2 is converted into bicarbonate ions then oxaloacetate
How many C in oxaloacetate
4C
What happens to oxaloacetate when produced
Can’t be transported within plants, so turned to malate (4C) which can move to chloroplast of bundle sheath cells
What happens to malate after it’s converted form oxaloacetate
In bundle sheath cells, it gets decarboxylated into 3C (pyruvate) and CO2
What happens to pyruvate after malate gets decarboxylated
Goes back to mesophyll chloroplast, converted to Phosphoenolpyruvate and then converted to HCO3 ions to produce oxaloacetate
What’s point of C4 pathway
Get high concentrations of CO2 in calvin cycle from these reaction cycles
What temp can C4 stay decent at
40-50 degrees
Why is C4 able to stay good at higher temps than C3
Since photorespiration is less, when sped up by hot temps it’s less impactful, basically a good adaptation for high temps
Does C4 plants increase near the equator
yes!
What’s C4 plant patterns at higher alttitudes and why
C4 more common lower down since temperature higher, high altitudes higher rainfall and colder so C3 more dominant
Hows C4 at water efficiency?
Way better than C3, like twice as good ~280-350water use efficency
Hows C3 at water efficency?
Kinda lame, ~550-700ish water efficency
When did C4 evolve in monocots
Around 21-35Ma
When did C4 evolve in dicots
Around 15-21Ma
How many indy origins of C4 pathway
like 62 WOwoWOwo tends to be in low c02 hot dry areas
how much of earth has rice as taple grain
like 50%
Is rice efficient as a C3 plant?
No. Rice has low light-conversion efficiency, high photorespiration. High n requirements and high water requirements.
What would be the use of C4 rice?
The development of C4 rice could increase yield up to 50% and spread available conditions for rice growth.
how to get c4 r1ce illegally?
genetic modfiication wooo
What about legal C4 Rice?
gotta do mutagenesisis, intense radiation and hoping c4 somehow happens , luck based
Name an important factor in developing C4 rice/
Get bundle sheaths closer! Decreasing the distance between the mesophyll and the bundle sheath.
What is mutagenesis?
The purposeful induction of mutations via radiations, hoping some of these mutations are useful.
Why may C4 rice be impossible?
Since rice always grew in standing water, there’s never been a pressure to develop into a C4 plant.
What % NPP do the 3% of plants that are C4 carry out?
3% of C4 plants carry out 25% of total plant NPP.
