PHOTOSYNTHESIS

Question 1

What are flowering plants main class of pigments

Answer 1

Chlorophyll
Carotenoids

Question 2

What is the peak wavelength for chlorophyll a

Answer 2

43, 670-680

Question 3

What is the pigment colour for chlorophyl a

Answer 3

Yellow - green

Question 4

What is the peak wavelength of chlorophyll b

Answer 4

480, 650

Question 5

What is the pigment colour of chlorophyll b

Answer 5

Blue - green

Question 6

What is the peak wavelength for b-carotene

Answer 6

425 - 480

Question 7

What is the pigment colour for b-carotene

Answer 7

Orange

Question 8

What is the peak wavelength for xanthophylls

Answer 8

400 - 500

Question 9

What is the pigment colour of xanthophylls

Answer 9

Yellow

Question 10

Which regions do chlorophyll mainly absorb light energy and which colour does this reflect

Answer 10

Red - blue violet

Green

Question 11

Which regions do carotenoids absorb light energy and what colour does this reflect

Answer 11

Blue - green

Yellow - orange

Question 12

What is the absorption peak of PSI

Answer 12

700nm

Question 13

What is the absorption peak of PSII

Answer 13

680nm

Question 14

What are the 3 products in light dependent stage

Answer 14

ATP
RED NADP
OXYGEN

Question 15

Define phosphorylation

Answer 15

Addiction of phosphate ion into ADP

Question 16

Define photo phosphorylation

Answer 16

Using light energy

Question 17

What photo system does non cyclic photophosphorylation involve

Answer 17

PSI and PSII

Question 18

What photo system does CYCLIC photophosphorylation involve

Answer 18

PSI

Question 19

Describe the process of cyclic photophosphorylation

Answer 19

• light energy is absorbed by PSII, causing electrons to get excited by chlorophyll a molecules in the reaction centre
• these are picked up by an electron acceptor which passes them down into ETC back into PSI
• the energy that is released from the ETC is phosphorylated to produce ATP

Question 20

Describe the process of non cyclic photophosphorylation

Answer 20

• light is absorbed by PSII, exciting electrons in chlorophyll to a higher energy level
• this is picked up by electron acceptor and goes through ETC
• as electrons move through ETC, they lose energy which is used to actively pump protons into thylakoid space creating proton gradient
• protons diffuse back into ATP synthase - phosphorylation of ADP to ATP
• photolysis of water is used to replace lost electrons in PSII
• electrons reach PSI where they are again excited by light from absorption
• reduced NADP is formed

Question 21

Describe fixation in light independent reaction

Answer 21

• RuBP reacts with carbon dioxide
• catalysed by enzyme RuBisCo
• forming 2 molecules of glucose-3-phosphate

Question 22

Describe reduction in light independent reaction

Answer 22

• each molecule of GP is reduced into triose phosphate
• this reaction used reduced NADP and ATP from light dependent reaction

Question 23

Describe regeneration in light independent reaction

Answer 23

• ribulose bisphosphate is regenerated using ATP

Question 24

What are 4 limiting factors of photosynthesis

Answer 24

Carbon dioxide
Light intensity
Temperature
Water

Question 25

Explain how light intensity is a limiting factor of photosynthesis

Answer 25

If low = decrease photosynthesis rate due to less reduced NADP and ATP produced in the light dependent stage If high = increase rate of photosynthesis due to more reduced NADP and ATP production in light dependent stage

Question 26

Explain how carbon dioxide is a limiting factor for photosynthesis

Answer 26

Is high concentration = increase photosynthesis, light independent stage working at a faster rate so more GP, TP RUBP regenerated If low concentration = decrease photosynthesis, light independent stage working at a slower rate

Question 27

Explain how temperature is a limiting factor for photosynthesis

Answer 27

If high = increase rate of photosynthesis, more kinetic energy within RuBisCO enzyme so light independent stage can work at a faster rate but can denature If low = decrease rate of photosynthesis, RuBisCO enzyme works at a much slower rate

Question 28

How is water a limiting factor for photosynthesis if low

Answer 28

If low / scares = stomata closes so carbon dioxide is also prevented from diffusing in