Gas Exchange Flowering plants Flashcards
Topic 2 G.1
DIFFUSION IS
the movement of molecules from an area of high concentration to an area of low concentration
diffusion drives the process of
gas exchange
respiration and photosynthesis rely on the exchange of (2)
oxygen and carbon dioxide
what cells respire
all living cells
in respiration, The cells use ____ in respiration so the concentration is always ____ inside the respiring cells
oxygen
low
in respiration, carbon dioxide diffuses from _____ the leaf to ____ the leaf so from ___ concentration to a ____ concentration
inside
outside
high
low
plant cells can only photosynthesize when
there is enough sunlight
process of photosynthesis needs the uptake of ____ and release of ____
carbon dioxide
oxygen
concentration of CO2 is low in photosynthesizing cells because
cells use carbon dioxide in photosynthesis so go from outside to inside ( high to low)
in photosynthesis oxygen diffuses from
a high concentration ( inside the leaf) to a low concentration (outside)
oxygen goes from ___ the leaves to ____ the leaves in photosynthesis
inside to outside
why is there hardly any CO2 in the leaf in photosynthesis
because it is used up a lot
how does oxygen diffuse out the leaf
through the stomata
photosynthesis only happens during the
day
plants respire
all the time
why do plants respire all the time
to get the energy they need to live
during the day, plants make ____ oxygen by photosynthesis than in respiration.
so they _____ oxygen
more
release
during the day, plants ___ __ more carbon dioxide than they produce so ____ ___ carbon dioxide (photosynthesis)
use up
take in
at night plants only
respire
so during the night plants release ____ and take in ____
take in oxygen
release carbon dioxide
how are leaves adapted for efficient gas exchange structure/outside (3)
- short diffusion distance (thin)
- large surface area (flat)
- stomata (allowing diffusion )
adaptations of the internal leaf structure (5)
- air spaces Air spaces to allow gas movement around the loosely packed mesophyll cells
- Many stomata in the lower epidermis open in sunlight to allow gas movement in and out of the leaf
- Thin cell walls allow gases to move into the cells easily
- Moist air which gases can dissolve into for easier movement into and out of cells
- the close contact between the cells and the air spaces allows efficient gas exchange for photosynthesis and respiration
3 key gases for leaf gas exchange
- CO2
- oxygen
- water vapour
when is water vapour released
respiration and transpiration
when is oxygen released
photosynthesis
when is carbon dioxide released
respiration
where are the stomata found
between the guard cells
when do stomata close
when the guard cells lose water ( by osmosis) to the epidermal cells
what are stomata
little holes or spaces found between 2 guard cells on the lower epidermis of the leaf
guard cells are responsible for
opening and closing of stomata pore which controls gas exchange and water loss
what does the stomata pore control
loss of water and gas exchange
are stomata open in the night, why
no because they’re open when there is plenty of water and sunlight
what does the guard cell control
The guard cells control the opening and closing of the stomata
during the daytime plants …
respire and do photosynthesis
if plants respire during the night, it means there is ( movement of gases)
this means that there is a net movement of oxygen into the plant and a net diffusion of carbon dioxide out of the plant during the nighttime
at low intensities, the rate of photosynthesis is ____ to rate of respiration
meaning that the net movement of gases is
equal
This means that there is no net movement of oxygen or carbon dioxide in either direction
PRACTICAL EFFECT OF LIGHT ON GAS EXCHANGE IN PLANTS
- Measure out 20 cm3 hydrogencarbonate indicator into 4 boiling tubes
- Put some cotton wool into each boiling tube
- Label the boiling tubes A-D and set them up as follows:
- Tube A - No leaf (control tube)
- Tube B - Place a leaf in the tube and leave in the light
- Tube C - Place a leaf in the tube and wrap it in aluminium foil to block out the light
- Tube D - Place a leaf in the tube and wrap it in gauze to allow partial light
- Put a LID into the top of each tube
- Leave all 4 tubes in the light for 30 minutes
what should the results of the practical be
Tube A- should remain orange/red to show There has been no net movement of CO2
Tube B- will turn purple as there is less carbon dioxide than atmospheric levels
Tube C- will turn yellow as carbon dioxide levels increase above atmospheric levels
Tube D- no net change in carbon dioxide levels and the indicator remained orange/red
in photosynthesis, where does the carbon dioxide get diffused into (part of the leaf)
chloroplasts
always use word NET
YES
