Photosynthesis

Question 1

Whats the overall equation for photosynthesis

Answer 1

6CO2 + 6H20 + light - C6H12O6 + 6O2

Question 2

Whats the overall equation for Aerobic Respiration

Answer 2

C6H12O6 + 6O2 - C6H12O6 + 6O2

Question 3

What enzyme catalyses synthesis of ATP

Answer 3

ATP synthase

Question 4

ATP synthesis is known as what process

Answer 4

Phosphorylation

Question 5

What enzyme catalyses breakdown of ATP

Answer 5

ATPase

Question 6

ATP is broken down by what process

Answer 6

Hydrolysis

Question 7

Name 4 benefits of ATP

Answer 7

• small/soluble for transport
• easily broken down
• cant pass out of cell so cell has immediate energy
• releases only small, manageable amount of energy

Question 8

Whats the compensation point

Answer 8

when photosynthesis and respiration occur at the same rate, no net loss/gain of carbon

Question 9

Where does photosynthesis take place

Answer 9

Chloroplasts

Question 10

name 3 features of chloroplasts

Answer 10

• surrounded by envelope with inter membrane space
• outer membrane s highly permeable
• 2 distinct regions: stroma and grana, which consist of stacks of thylakoid membranes

Question 11

Why does the stroma contain some loops of DNA

Answer 11

for proteins needed in photosynthesis

Question 12

Photosynthetic pigments are found where

Answer 12

Thylakoid membrane

Question 13

primary pigments are

and accessory pigments are

Answer 13

reaction centres

light harvesting systems

Question 14

Name the 2 photosystems and their wavelengths

Answer 14

PS1 700nm

PS2 680nm

Question 15

Name the 3 things the light energy absorbed is used for

Answer 15

• photophosphorylation
• making NADP into NADPH
• Photolysis

Question 16

Photosystems are linked by what

Answer 16

electron carriers

Question 17

the photosystems and electron carriers form an

Answer 17

electron transport chain

Question 18

whats am electron transport chain

Answer 18

chain of proteins through which excited electrons flow

Question 19

Summarise non-cyclic photophosphorylation in 4 steps

Answer 19

• photon absorbed by PSII exciting electrons in chlorophyll moving them towards PSI
• Electrons from PSII replaced by electrons from photolysis. This produces/releases O2.
• Energy lost from electrons travelling down ETC used to pump H+ into thylakoid. Creates H+ conc gradient across membrane. H+ moves into stroma via ATP synthase. Energy from this movement makes ATP.
• Photon absorbed by PSI, excites electrons further. Electrons transferred to NADP with H+ from the stroma, reduces NADP to NADPH. Catalysed by NADP reductase

Question 20

State the reaction for photolysis

Answer 20

H2O - 2H+ + 1/2O2

Question 21

Whats another name for the light independent reaction/calvin cycle

Answer 21

carbon dioxide fixation

Question 22

Summarise the calvin cycle in 3 steps

Answer 22

• CO2 combines with 5-C RuBP to form 2x 3-C GP. Catalysed by RuBisCo
• GP reduced by 2x NADPH to 2x 3-C TP. Uses 2x ATP
• 5/6 TP produced is used to regenerate RuBP. Uses last ATP from light dependent reaction.

Question 23

How many turns of the Calvin cycle are needed to make one Hexose sugar

Answer 23

6

Question 24

How many turns of the Calvin cycle are needed to make a TP molecule not used to regenerate RuBP

Answer 24

3

Question 25

How many ATP and NADPH are needed for 6 turns of the Calvin cycle

Answer 25

18ATP | 12NADPH

Question 26

Name the 3 limiting factors of photosynthesis

Answer 26

- Light intensity - Temperature - Carbon Dioxide

Question 27

what the optimum temp for most plants

Answer 27

around 25°C

Question 28

name 3 problems that occur at high temps

Answer 28

- enzymes denature - stomatal closure avoid water loss, less CO2 intake - thylakoid membrane may be damaged, reduce rate of light dependent reaction by decreasing number of sites for electron transfer

Question 29

Increasing CO2 conc up to what increases rate | After this point what happens

Answer 29

0.4 | stomata start to close

Question 30

What else can affect photosynthesis

Answer 30

water stress as the stomta will close to preserve water decreasing CO2 intake

Question 31

What effect will low light intensity have on concentration of GP, RuBP and TP

Answer 31

GP higher | RuBP and TP lower

Question 32

What effect will low CO2 conc have on concentration of GP, RuBP and TP

Answer 32

RuBP higher | GP and TP lower