photosynthesis

Question 1

define reduction

Answer 1

loss of oxygen, gain of electrons

Question 2

define oxidation

Answer 2

gain of oxygen, loss of electrons

Question 3

name the two stages of photosynthesis

Answer 3

light dependent, light independent reactions

Question 4

state the location of the light dependent stage of photosynthesis

Answer 4

thylakoids

Question 5

state the location of the light independent stage of photosynthesis

Answer 5

stroma

Question 6

describe photoionisation stage in photosynthesis

Answer 6

chlorophyll absorbs light energy and electrons gain energy/become excited. electrons leave the chlorophyll, so the chlorophyll is oxidised, this is photoionisation

Question 7

describe stage 2 of light dependent reaction in photosynthesis

Answer 7

excited electrons passed from electron carrier to electron carrier in a series of redox reactions. the series of electron carriers is present in the thylakoid membrane. each electron carrier is a different energy level than the next so the electrons lose energy

Question 8

describe stage 3 of light dependent reaction in photosynthesis

Answer 8

the energy is used to pump hydrogen ions against their concentration gradient from the stroma inside the thylakoid

Question 9

describe stage 4 of light dependent reaction in photosynthesis

Answer 9

hydrogen ions move down their conc gradient from a high conc in the thyalkoid to low conc in the stroma through atp synthase. atp synthase combines adp and pi to form atp

Question 10

describe stage 5 of light dependent reaction in photosynthesis

Answer 10

hydrogen ions pass through atp synthase and are taken up with electrons by NADP to form reduced NADP

Question 11

describe stage 6 (photolysis) of light dependent reaction in photosynthesis

Answer 11

photolysis splits water with light, which provides electrons to the chlorophyll to replace ones lost during photoionisation

Question 12

explain how chloroplasts are adapted to carry out light dependent reaction

Answer 12

thylakoid membranes- supplies a large surface area for chlorophyll, electron carriers and enzymes to attach.
proteins in grana- hold chlorophyll in precise place for max absorption of light
ATP synthase in thylakoid membranes for atp production

Question 13

explain how carbon dioxide absorbed by plants is incorporated into organic molecules

Answer 13

carbon dioxide enters the stroma by diffusion and reacts with 5C RuBP to form an unstable 6C intermediate then 2x 3C GP, in the presence of enzyme RuBisCo

Question 14

what are the roles of ATP and NADPH in the light independent reaction

Answer 14

ATP and NADPH are used to convert the 2 molecules of GP to TP. ATP is then used to convert TP back to 5C RuBP, losing a C atom which is used to make organic molecules such as glucose

Question 15

describe the events in the Calvin Cycle/Light independent reaction

Answer 15

carbon dioxide and RuBP form 2x GP in the presence of enzyme RuBisCo. GP converted to TP using ATP and NADPH and then ATP is used to convert TP back to 5C RuBP where it loses a C atom to form organic molecules