Photosynthesis

Question 1

What are the 2 groups of reactions called

Answer 1

Light independent / Calvin cycle
Light dependant

Question 2

What happens to chlorophyll when it absorbs light

Answer 2

Photoionised
Electrons become excited
Causes production of ATP and NADPH

Question 3

Where is chlorophyll found

Answer 3

Internal membranes of chloroplasts / another word for thylakoid membranes

Question 4

What is chemiosmosis

Answer 4

Diffusion if Hydrogen ions (protons)
Through partially permeable membrane/ ATP synthase channels

• generates ATP

Question 5

What enzyme catalyses reaction between RUBP and CO2
What is this proscess called

Answer 5

Rubisco
Carbon fixation

Question 6

What are energy sources for Calvin cycle

Answer 6

From Light dependant reaction
- ATP
- NADPH (reduced NADP)

Question 7

What is the product of reacting co2 and rubp (ribulose)

Answer 7

Unstable carbon compound
Splits to = 2 x GP
( glycerate 3-phosphate)

Question 8

What is triose phosphate used for ?

Answer 8

Regeneration of RUBP - Calvin cycle can continue
Making useful organic molecules

Question 9

Name 3 molecules that can be produced from photosynthesis

Answer 9

Glucose, cellulose, starch

Question 10

What is photolysis

Answer 10

During LDR
Water split into - oxygen , 2 protons, 2 electrons
- used to reduce NADP

Question 11

How can chlorophylls be separated experimentally

Answer 11

Paper chromatography or thin layer

Question 12

Role of dehydrogenase

Answer 12

Catalyses reaction where :
Electrons are accepted by NADP

Question 13

What is GP reduced to ?

Answer 13

6 x TP

Question 14

Which reaction is co2 taken in

Answer 14

Light independent

Question 15

Summary of light dependent reactions

Answer 15

1- photolysis, water broken into protons electrons and oxygen

2- photoionisation, chlorophyll absorbs light
- excited electron moves down electron transport chain
- Protons are actively transported into membrane and diffuse back through ATP synthase channels

3 - produces ATP and NADPH (reduced NADP) for light independent
4- electrons + protons from photolysis reduce NADP = NADPH, replace electrons lost from electron transport chain

Question 16

Summary of light independent reactions

Answer 16

1- co2 fixed with RUBP
2- GP reduced to TP
3- production of organic compounds and recycling of RUBP

• Calvin cycle uses ATP and NADPH from light dependant as energy

Question 17

What enzyme catalyses co2 + RUBP

Answer 17

Rubisco

Question 18

What 2 molecules reduce GP - TP

Answer 18

ATP
Reduced NADP( NADPH)
- both made in light dependent

Question 19

Name 2 other types of molecule that can be produced from Calvin cycle

Answer 19

Lipids
Amino acids

Question 20

Site of chemiosmosis

Answer 20

Across thylakoid membrane

Question 21

Site of light independent

Answer 21

Stroma

Question 22

What sugars can be produced from Tp

Answer 22

• hexose sugars - glucose
• 2x TP = 1 glucose

Question 23

Where is chlorophyll found

Answer 23

Thylakoid membranes

Question 24

Site of light dependant

Answer 24

Across thylakoid membranes mainly

Question 25

How are chloroplasts adapted to photosynthesis

Answer 25

• stacks of thylakoid membranes(grana) provide large surface area
• Chloroplasts have DNA + ribosomes allowing them to synthesis proteins needed

Question 26

How many molecules of TP are needed for one glucose

Answer 26

2
Therefore 2 cycles of Calvin cycle = 1 glucose

Question 27

What do ATP and NADPH do in light independent reaction

Answer 27

ATP = provides energy for GP to TP
- provides P for RUP + TP = RUBP

NADPH= provides H + electrons for GP to TP
- reduces GP to TP
(Reduction is gain of electrons + hydrogen)

Question 28

How many carbons are in a TP molecule

Answer 28

3
- Therefore 2x TP = a 6 carbon compound = glucose