Ch.7.4 Flashcards
Both respiration and photosynthesis involve ________________________________________________________________________________________________________.
exchange of carbon dioxide and oxygen between living things and their environment
What is the colour of hydrogencarbonate indicator if the carbon dioxide level is >0.03%?
yellow
What is the colour of hydrogencarbonate indicator if the carbon dioxide level is =0.03%?
red
What is the colour of hydrogencarbonate indicator if the carbon dioxide level is <0.03%?
purple
Green plants can carry out both ________________ and ________________.
photosynthesis, respiration
What does net gas exchange in plants depend on?
The relative rates of photosynthesis and respiration.
During daytime, ________________________________________________ take place, but the __________________________________ is higher than the ______________________________________.
both photosynthesis and respiration, rate of photosynthesis, respiration
Name the two net gas exchange indicators we can measure in daytime.
- net uptake of carbon dioxide
- net release of oxygen
At night, ________________________________. Only ________________________ takes place.
photosynthesis stops, respiration
Name the two net gas exchange indicators we can measure at nighttime.
- net uptake of oxygen
- net release of carbon dioxide
Where is gas exchange carried out in plants?
The tiny pores on the leaf epidermis, aka stomata
Why are stomata only found on the lower surface of the leaf?
It is to avoid direct contact with sunlight.
Surrounding each stoma are _________________________________.
two guard cells.
What are the functions of guard cells?
They control the opening and closing of the stoma.
In the daytime, the guard cells are ________________________. They ___________ the stoma.
full of water, open
Why do guard cells open in the daytime?
So that the plants can take in carbon dioxide from the air for photosynthesis, and give out the oxygen produced through the stomata.
At night, the guard cells _______________ as they _____________ ______________, and so the stoma _______________.
shrink, lose water, closes
When the stoma is open in the ________________, the guard cells are ________________/ ________________.
daytime, swollen, turgid
When the stoma is closed at ________________, the guard cells are ________________/ ________________.
night, shrunken, flaccid
Stomata are very ________________ in size. They can only be observed using a ________________ with the magnification of about x__________.
small, microscope, 400
We need to take in ________________ from the air and remove ________________ ________________ from our bodies. There is _____________ ________________ between our ________________ and the ____________________.
oxygen, carbon dioxide, gas exchange, body, environment
How can we find evidence for gas exchange between us and the environment?
By comparing the composition of the air we breathe in (inhaled air) and the air we breathe out (exhaled air)
How is the oxygen content of inhaled/ exhaled air tested? Why?
With a burning splint. This is because a glowing splint requires a large amount of oxygen to relight, but both inhaled air and exhaled air do not have enough oxygen to relight a glowing splint.
How is the carbon dioxide content of inhaled/ exhaled air tested?
With hydrogencarbonate indicator.
Exhaled air contains ______________ oxygen than inhaled air.
less
Exhaled air contains ______________ carbon dioxide than inhaled air.
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