Gas exchange - Plants Flashcards
What is the equation for photosynthesis?
6CO2 + 6H2O —> C6H12O6 + 6O2
carbon + water -> glucose + oxygen
dioxide
What is the equation for respiration
C6H12O6 + 6O2 -> 6H2O + 6CO2 + energy in the form of ATP
When is the respiration rate higher than photosynthesis?
At night
In low light levels
At low temperatures
What happens when the respiration rate is higher than photosynthesis ?
There is a NET uptake of oxygen and loss of carbon dioxide from the cells
When does respiration occur?
All the time
(day and night)
When does photosynthesis happen?
Only occurs during the day
When is the rate of photosynthesis greater than respiration?
At high light intensities
What happens when the rate of photosynthesis is greater than respiration
There is a NET uptake of carbon dioxide and loss of oxygen from the cells
What are stoma?
pore for gas exchange
What are the palisade mesophyll
Adapted for photosynthesis as they have many chloroplast
What happens to stomata during the day ?
Stomata - Open for gas exchange
What happens to photosynthesis during the day?
Needs CO2, some for respiration, most from external air
What happens to respiration during the day?
Needs O2 from photosynthesis
Remaining O2 diffuses out
What happens to the stomata at night
Stomata - Closed to prevent water loss
What happens with respiration at night
Only needs O2 from air spaces in spongy mesophyll layer
What are the main structures for gas exchange in plants?
Stomata
Mesophyll
Air spaces
How are stomata adapted for gas exchange ?
Open and close to allow gases to enter the leaf
How is the mesophyll adapted for gas exchange?
Many = large SA, thin, most cell walls allow diffusion
How do air spaces affect gas exchange?
They reduce the distance for gas exchange
How does a leaf being thin and flat adapt to its role ?
Large SA:V ratio
—> max light absorption & short diffusion path for gases to diffuse all cells
How do the palisade mesophyll cells
with many chloroplasts near its surface affect gas exchange?
Light absorption- photosynthesis
chlorophyll in chloroplasts which absorb light
How do the air spaces in the spongy mesophyll affect gas exchange?
Allows gases to diffuse through leaf to reach all cells
How do numerous stomata affect gas exchange
Allow gases to diffuse in/out of the leaf
How do guard cells on either side of the stomata affect gas exchange
They can close stomata to prevent excessive water loss
