Flashcards
A Level Biology- Photosynthesis and Limiting Factors
Cards in this deck (27)
- 1Where does the Light Dependant stage take place?In the Thylakoid Membranes of the Chloroplast
- 2What is the point of the Light Dependant stage?To convert light energy to chemical energy (ATP)
- 3Which photosystem does begins the Light Dependant stage?Photosystem II
- 4How many electrons move from Photosystem II to the first Electron Acceptor?2 electrons
- 5What occurs as electrons travel down the electron transfer chain to Photosystem I?Photo-phosphorylation. ATP is produced by chemiosmosis. (ADP + Pi = ATP)
- 6When the electrons continue to rotate from the 1st Electron Acceptor to the PS I to the 2nd Election Acceptor again and again what is it called?Cyclic photo-phosphorylation
(This produces more ATP than a normal Light Dependant stage which is non-cyclic) - 7Which reaction is going on during the Light Stage to replenish the supply of electrons to PS II?H2O = 2e-, 2H+, 1/2 O2
- 8What happens at the end of the Light Dependant Stage?We are left with two electrons and the two hydrogen atoms from the breakdown of water. The hydrogen atoms go on to form NADPH (reduced NADP)
- 9What are the products of the Light Stage?Oxygen, ATP, NADPH
- 10Which molecule is at the beginning of the Calvin Cycle?RuBP (Ribose biphosphate) which is a 5 carbon molecule and is a CO2 acceptor
- 11What happens to the rubisco enzyme above 25 degrees temperature?It begins to accept oxygen instead of carbon dioxide which stops the Calvin Cycle.
- 12What happens as RuBP is converted to 2 molecules of GP (Glycerate 3-phosphate)?With the aid of the rubisco enzyme, CO2 diffuses in and carboxylation occurs.
- 13How many carbons are in a molecule of GP (glycerate 3-phosphate)?Three
- 14What is required in to turn the two molecules of GP into two molecules of TP (triose phosphate)?ATP and NADPH from the Light-Dependant stage. (NADPH donates its hydrogen and becomes NADP again).
- 15What do plants use the TP for?It can be built up into glucose or other carbohydrates (two TP make glucose) or can be stored as starch, sucrose or used to make new cell walls.
- 16How is the RuBP regenerated in the Calvin Cycle?10 of the 12 TP molecules made are used to regenerate the RuBP. This is 5/6 of the TP.
- 17Where does the Calvin Cycle take place?In the stroma
- 18What happens when a plant is put in the dark?The Calvin Cycle can continue up until the point of GP being converted to TP. This can't occur as the prducts of the light dependant stage are required to do this.
- 19What are the roles of Chlorophyll A and Chlorophyll B in the photosystems?Chlorophyll A- Causes the electrons to get excited so they can continue down the electron transfer chain.
Chlorophyll B- This and Carotenoids filter the light into the Photosystem - 20What happens to produce ATP?As electrons are carried through the electron transfer systems, the H+ molecules are pumped into the spaces between the thylakoid membranes. To get back, they pass through protein channels that are attached to the enzyme that makes ATP, producing it in the process.
- 21What happens when a plant is exposed to too high of a temperature?If the temperature is way too high (around 45 degrees) , the enzymes involved in the Calvin Cycle (such as rubisco) will denature. if the temperature is 25 degrees, rubisco will begin picking up oxygen instead of carbon dioxide.
- 22What happens if a plant is exposed to too much carbon?It is toxic to the plant as CO2 can dissolve into carbonic acid which will cause the PH of the plant to change.
- 23What happens if the temperature of a plant drops below 10 degrees?Lack of kinetic energy means there is a lack of collisions of enzymes and substrates so reactions slow.
- 24What are the limiting factors of photosynthesis?Carbon dioxide concentration, temperature, light wavelength and light intensity, amount of pigment and the PH
- 25Which wavelengths do plants absorb best?Blue and red light is more readily absorbed by the chlorophyll, green light is mostly reflected and isn't absorbed.
- 26On a graph of limiting factors, why is it likely to plateau?Another limiting factor will stop the rate from infinitely increasing.
- 27Why is water not a limiting factor?Plants can control their water loss by closing the stomata.
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- A level Biology (Module 5 ) Flashcards on A Level Biology- Photosynthesis and Limiting Factors , created by Emma Lloyd on 28/09/2016.
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