Gas Exchange in Plants + Experiment

Question 1

why are plants constantly respiring?

Answer 1

because all their cells require energy

Question 2

when is photosynthesis faster than respiration?

Answer 2

during the day, at higher light intensities - there will be a net uptake of carbon dioxide and net release of oxygen, and it is excreted from the leaves

Question 3

when is respiration faster than photosynthesis?

Answer 3

in the dark, and at low light intensities - there will be a net uptake of oxygen and net release of carbon dioxide, and it is excreted from the leaves

Question 4

what does gas exchange occur in plants?

Answer 4

between the air spaces in the leaves and the atmosphere - carbon dioxide and oxygen diffuse, moving through the stomata

Question 5

describe the investigation about gas exchange in plants

Answer 5

• this investigation uses sodium hydrogen-carbonate indicator to show the changes in carbon dioxide concentration in the air surrounding leaves in different light conditions
• leaves, for example, are placed in three of four boiling tubes containing a small volume of sodium hydrogen carbonate indicator (red/orange when in atmosphere)
• one tube is placed in bright light, one is wrapped in foil, one is wrapped in tissue paper (weak light) and the tube with a dead leaf is also left in bright light and the tubes are left for 40 minutes

Question 6

what are the results of the gas exchange in plants experiment?

Answer 6

leaf in tube with foil cover = yellow indicator because respiration is higher than photosynthesis so more carbon dioxide

leaf in tube with tissue paper cover = red indicator because respiration is equal to photosynthesis so the gases are equal

leaf in clear tube = pink indicator because photosynthesis is higher than respiration so more oxygen

boiled leaf = red indicator because there are no living cells