Leaves and Stomata Flashcards
What are stomata and what do they do
Stomata are gaps in the lower epidermis of leaves that make the diffusion of gas easier
What diffuses through the stomata
1) Water Vapour
2) Oxygen
What must happen for the stomata to close
The guard cells lose water and return to a limp state.
How does the stomata open up
The guard cells can open the stomata by taking up lots of water, causing them to swell.
What does the stomata do when water is abundant and why
The plant can afford to lose water, so it opens the stomata to allow gases for photosynthesis to move freely in and out of the leaf.
What does the stomata do when water is scarce
Stomata close in order to prevent further water loss.
This is achieved by guard cells returning to a limp state after they lose water.
Why are the stomata closed at night
Stomata close because, in the absence of sunlight, carbon dioxide is not required for photosynthesis.
At this time, their only objective is to prevent water loss.
The state of stomata (open or closed) achieves what?
a balance between allowing gases for photosynthesis into the leaves, and conserving water in the plant.
when does the hydrogencarbonate indicator change colour
depending on how much carbon dioxide is in a solution
what can a hydrogencarbonate indicator show
how much photosynthesis and respiration an aquatic plant (like pondweed) is doing, by adding it to the water the plant is in.
what colour does the hydrogencarbonate turn when there are high levels of carbon dioxide
it turns yellow when there is a high concentration of carbon dioxide present
what does the fact that CO2 is produced in respiration and used up in photosynthesis suggest and how can you get this result when the colour of the indicator is yellow
it suggests that the plant is respiring more than it is photosynthesising.
you can get this result by keeping the plant in the dark
what colour does the hydrogencarbonate indicator turn when there are low levels of carbon dioxide
it turns purple when there is a high concentration of carbon dioxide present
what does the fact that CO2 is produced in respiration and used up in photosynthesis suggest and how can you get this result when the colour of the indicator is purple
this suggests the plant is photosynthesising more than it is respiring.
This result can be seen if the plant is kept in bright light.
what colour does the hydrogencarbonate indicator turn when in normal atmospheric levels of carbon dioxide
it turns red
