Photosynthesis Flashcards

Question

What is the action spectrum?

Answer 1

A graph that shows the rate of photosynthesis at different wavelengths if light

Answer 2

There is a close connection between greater light absorption and a faster rate of photosynthesis , suggesting that these pigments are responsible for absorbing the wavelengths of light used in photosynthesis to ,are glucose

Answer 3

Count the number of bubbles of O2 gas produced by pondweed (underwater plant) over a set period of time

Answer 4

- accessory pigments are grouped into clusters with associated proteins to form an antenna complex - the accessory pigmets absorb photons of light energy and funnel this down the antenna complex to the reaction centre - the reaction centre contains 2 chlorphyll a molecules and is found below the antenna complex - when photons of light energy reach chlorophyll a, electrons are excited to become high energy

Answer 5

- absorb photons of light energy - act as transducers - transferring the light energy to high energy electrons - this energy is then used to fuel proton pumps and synthesis ATP

Answer 6

PSI has chlorphyll a that is 680nm (P680) PSII has chlorophyll a that is 700nm (P700)

Answer 7

- non-cyclic phosphorylation - cyclic phosphorylation

Answer 8

- light energy is passed from the accessory pigments (chlorophyll b, xanthophyll, beta-carotene) to 2x chlorophyll a (P680) in the reaction centre of PSII - photons of lights are also absorbed directly by chlorophyll a -exciting 2 electrons to a high energy state - high energy electrons are released from chlorophyll a, binding to he primary electron acceptor and passing down a chain of electron carriers down the electron transport chain - energy lost from electrons in the electron transport chain activates a proton pump so H= ions diffuse from the stroma into the thylakoid lumen - electrochemical gradient is established, allowing ATP synthesis from ADP and Pi - final electron acceptor is NADP+ which binds to H+, forming NADPH - photolysis of water (2H20 —> 4H+ + 4e- + 1/2O2) - low energy electrons from water replaces those lost from chlorophylll a in P680 and protons to reduce NADP+

Answer 9

A process that occurs in bacteria and primitive plants Higher lands use this process to provide extra ATP when CO2 is in short supply, or if levels of NADPH are very high ONLY PSI IS INVOLVED

Answer 10

- light energy is absorbed at PSI and channelled to chlorophylll a - electrons in the chlorophyll a become excited, energised, and released. They are then accepted by an electron acceptor and are passed down the same electron transport chain that is used by the electrons from PSII - protons are pumped from the stroma into the thylakoid space and ATP is produced from ADP+Pi - the electrons excited from PS! Return to PS! THERE IS NO PHOTOLYSIS AND NO INVOLVEMENT OF PSII

Answer 11

CYCLIC: ATP only NON-CYCLIC: ATP, NADPH, O2

Answer 12

- CO2 from the atmosphere is fixed with RuBP in a reaction catalysed by RuBisCo enzyme - this forms the unstable 6C compound, which splits into glycerate-3-phosphate (3C) - G3P is then reduced, simultaneously oxidising NADPH into NADP+, ATP is also hydrolysed and thee phosphate is transferred to G3P, forming 1 triose phosphate for every G3P (2 per RuBP) - one carbon atoms of the 6 is removed from the Calvin cycle and is used to produce organic molecules like glucose - 5 carbon atoms remain in the Calvin cycle and are used to regenerate RuBP so the cycle can begin again in another process that requires ATP

Answer 13

When CO2 falls, less RuBP is sued to fix CO2, but it continues to be regenerated from any triose phosphate present, using the ATP in the Calvin cycle so concentration of RuBP increases As less RuBP is used to fix CO2, less of the unstable ^C compound is formed, so less G3P is generated. Any G3P present is still reduced to TP using ATP hydrolysis and NADPH, so G3P concentration falls/decreases

Answer 14

- G3P increases in the dark, as CO2 is fixed not RuBP, but in the dark there is less light dependent products, so less G3P is reduced to triose phosphate, so [G3P] increases - glucose falls as it is used up in respiration and isn’t replaced by photosynthesis in the dark - RuBP is used to fix CO2 in the dark still, as the reaction is not dependent on products from the light dependent reaction. Concentration falls as it is not regenerated from TP due to a lack of ATP

Answer 15

- amylose (starch) - amino acids - fatty acids - cellulose

Answer 16

Taken up by roots, transported as nitrates in the xylem and as amino acids in the phloem FUNCTION: protein synthesis, synthesis of nucleic acids/DNA/RNA/nucleotides DEFICIENCY SYMPTOMS: reduced grout of organs, chlorosis (yellowing leaves due to inadequate chlorophyll production so no longer able to absorb light energy)

Answer 17

Absorbed as Mg2+ and transported in the xylem FUNCTION: for chlorophyll production and activation of ATP synthase DEFICIENCY SYMPTOMS: pronounced chlorosis between veins of older leaves as Mg is moved and transported to new leaves

Photosynthesis Flashcards

(41 cards)