photosynthesis topic 5

Question 1

where does the light dependant reaction take place?

Answer 1

thylakoid membrane

Question 2

Describe the light-dependent reactions of photosynthesis

Answer 2

• light energy exites electrons in chlorophyll
• water undergoes photolysis (by light) to produce oxygen, electron and H ions
• these electrons are used in the electron transport chain and to relpace that lost by chlorophyll
• photophosphorylation produces ATP
• NADP is reduced at the end og ETC

Question 3

where do the light independant reactions occur?

Answer 3

stroma

Question 4

Why is the Calvin cycle temperature sensitive but the light dependant reactions are not ?

Answer 4

Calvin cycle contains enzymes

Question 5

why would a cold solution of sucrose and buffer be used in a photosynthesis practical?

Answer 5

• cold + buffer used to stop enzyme denaturation
• sucrose used to stop osmotic loss of water from chloroplasts

Question 6

describe the main compounds in order in the calvin cycle

Answer 6

CO2 + RuBP –> GP –> GALP + Glucose –> RuBP

Question 7

what are the products of the light dependant reaction?

Answer 7

ATP + reduced NADP

Question 8

what is the reaction of the splitting of water in the LDR called?

Answer 8

photolysis

Question 9

describe what occurs in the photoionisation of chlorophyll

Answer 9

• light energy is absorbed
• electrons become exited
• electrons raised up an energy level to leave chlorophyll

Question 10

what is the equation for the photolysis of water?

Answer 10

H2O –> 1/2 O2 + 2e- + 2H+

Question 11

Describe where each product of the photolysis of water goes

Answer 11

• H+ picked up by NADP to form reduced NADP
• e- passed along electron transport chain
• O is a waste product

Question 12

Describe the role of RUBISCO in the production of GALP in the light-independent reaction.

Answer 12

• RuBISCO is an enzyme in the calvin cycle (1)
• catalyses carbon fixation when CO2 and RuBP combine (1)
• this forms GP (1)
• using ATP and reduced NADP GP is converted into GALP (1)

Question 13

when completing the photosynthesis practical what is DCPIP acting as?

Answer 13

NADP

Question 14

explain the relationship between structure and function of a granum in photosynthesis (3)

Answer 14

• granum formed from layers of thylakoid membranes to increase surface area
• contain chlorophyll to absorb light
• electron carrier molecules in thylakoid membranes involved in ATP production