Plant Gas Exchange Flashcards
What is excretion?
The removal of metabolic waste from an organism.
How do plants exchange gases?
By diffusion
What does the net exchange of gases depend on?
Light intensity
When does photosynthesis happen?
During the day only
Why must plants respire all the time?
To get the energy they need to live
In the day (high light intensity) why do plants release oxygen?
Because they make more oxygen by photosynthesis than they use in respiration
Why do plants take in carbon dioxide in the daytime?
Because they use up more carbon dioxide than they can produce.
What ways have leaves been adapted for efficient gas exchange?
Broad leaves
Thin leaves
Stomata
Guard cells
Air spaces inside the leaf
How is broad leaves an adaptation for efficient gas exchange?
Larger surface area so diffusion can occur quicker
How are thin leaves an adaptation for efficient gas exchange?
Gases have a short diffusion distance
How are air spaces in the leaf an adaptation for efficient gas exchange?
They let gases like carbon dioxide and oxygen move easily between cells and also increases the surface area for gas exchange
How are the stomata an adaptation for efficient gas exchange?
They let CO2 and O2 in an out of the cell
They close as it gets dark as photosynthesis can’t occur so they prevent water from getting out and drying out the leaf.
How are guard cells an adaptation for efficient gas exchange?
They change shape to open and close the stomata
Name an experiment that could be used for gas exchange.
Sodium hydrogen carbonate indicator to show changes in CO2 concentration
Describe the set up of an experiment to test gas exchange.
Living leaves are placed in 3 out of 4 test tubes with a dead leaf in the last one.
One tube is placed in bright light
One is wrapped in foil (no light)
One is wrapped in tissue paper (weak light)
The dead leaf is also in bright light
What colour would the sodium hydrogen carbonate indicator go in increasing levels of CO2?
yellow
What colour would the sodium hydrogen carbonate indicator go in decreasing levels of CO2?
purple
What colour is sodium hydrogen carbonate indicator?
orange
What colour would the indicator go in the tube with the foil cover and why?
It would go yellow as more carbon dioxide is being produced because it has no light so only respiration is occurring.
What colour would the indicator go in the tube with the tissue cover and why?
It would stay orange as the rates of respiration and photosynthesis are the same in the low light levels.
What colour would the indicator go in the tube in bright light and why?
It would be purple as the rate of photosynthesis is much higher than the rate of respiration so more carbon dioxide is being used up/ less is being produced
What colour would the indicator go in the test tube with the dead leaf in bright light?
It would have no colour change as there are no living cells.
What is the point of having the test tube with the dead leaf in it in bright light?
It is there as a control factor to prove that nothing else is affecting the indicator.
