Ch.11 - Photosynthesis Flashcards
Write the balanced equation for photosynthesis.
6CO2 + 6H2O =(sunlight+chlorophyll) C6H12O6 + 602
What is the role of photosynthesis?
Photosynthesis’ role is to make food for plants. Animals get food from plants so animals and plants get food from photosynthesis. Produces oxygen needed for respiration. It was responsible for forming fossil fuels.
What is photolysis? Write its balanced equation.
Photolysis is the splitting of water by light.
2H2O =(light) 4H+ + 4e- + O2
Where do plants get the CO2 required for photosynthesis?
Plants get CO2 from the atmosphere and from CO2 produced by respiration.
Where do plants get H2O required for photosynthesis?
H2O is absorbed from the soil by the plant’s roots.
How can you increase the rate of photosynthesis?
The use of artificial light sources. The use of artificial CO2 sources such as burning hydrocarbons.
Give 2 fates of energised electrons.
They can pass to electron acceptors or to NADP+ to make NADP-.
What is the fate of ATP that is produced in the light stage?
ATP supplies energy for the dark stage reactions.
What is the fate of NADPH that is produced in the light stage?
NADPH supplied protons and electrons for dark stage reactions.
What is the fate of O2 that is produced in the light stage?
O2 is used in respiration or released into the atmosphere.
Give an account of the events in pathway 1(cyclic).
Energised electrons are released by the electron acceptor and are brought from carrier to carrier. The energy from the electrons are used to combine ADP and P to form ATP and water.
Give an account of the events in pathway 2(non-cyclic).
2 energised electrons combine with NADP+ to form NADP-. H+ is added from the proton pool to form NADPH. Water is photolysed to produce electrons and O2. ATP is formed from ADP + P using the electrons.
Give an account of the events in the darks stage.
NADPH from the light stage supplies H+ and electrons to CO2. The resulting NADP- goes back to the light stage. ATP from the light stage supplies energy to CO2 and the resulting ADP returns to the light stage. Using this CO2 is converted to C6H12O6.
Mandatory experiment: To investigate the influence of light intensity on the rate of photosynthesis.
Add NaHCO3 to water so that there is a constant concentration of CO2. Cut a section of elodea and place the cut end upwards in the test tube. Place the test tube in a water bath of a constant 25C. Place the lamp 1m from the elodea and leave for 5 minutes to allow the system to adjust. Count the bubbles of oxygen released per minute. Repeat and find average. Increase light intensity and graph.
