Biology - Unit 4 - Photosynthesis

Front 1

What does the light dependant require?

Back 1

Energy from a light source

Front 2

Where does the light dependant reaction take place?

Back 2

Thylakoid membranes

Front 3

What is the light energy absorbed by?

Back 3

Photosynthetic pigments in the photosystems which converts it into chemical energy.

Front 4

What is the light energy used for in the light dependant reaction?

Back 4

The energy is used to add a phosphate group to ADP to make ATP and to reduce NADP to form reduced NADP (nadph)

Front 5

What does ATP do?

Back 5

Transfer energy

Front 6

What does red NADP do?

Back 6

This transfers hydrogen

Front 7

ATP is mad by....

Back 7

Photophosphorylation

Front 8

What three reactions occur during the light dependant reaction?

Back 8

The making of ATP from ADP and an inorganic phosphate. Making of reduced NADP from NADP. The splitting of H2O into protons, electrons and oxygen O2.

2H2O = 4H+ + 4e- + O2

Front 9

Describe the light Dependant reaction

Back 9

1 - light energy is absorbed by photosystem 2.

2 - light energy excites the electrons in the chlorophyll causing the now high energy electrons to move along the electron transport chain. To photosystem 1.

3 - As the excited electrons from chlorophyll leave photosystem 2 they must be replaced.

4 - light energy splits water into H+ ions, electrons and O2.

REACTION H2O = 2H+ + 1/2 O2

5 - Excited electrons loose energy as they move along the electron transport chain.

6 - This energy is then used to transport protons into the thylakoid so that the thylakoid has a higher concentration or protons than the stroma.

7 - This forms a proton gradient across the membrane, protons move down the conc gradient into the stroma, via an enzyme called enzyme ATP ase.

8 - The energy from this movement combines ADP and a inorganic phosphate to form ATP.

9 - Light energy is then absorbed by photosystem 1the electrons in there move to a higher energy level.

10 - Electrons are transferred to NADP with a proton (H+ ion) from the stroma to form reduced NADP (NADPH).

Front 10

What does the diagram look like which shows the Light Dependant Reaction?

Back 10

Pic

Front 11

What is the Light Independent reaction also known as?

Back 11

The Calvin Cycle

Front 12

Where does the light independent reaction take place?

Back 12

The stroma of the chloroplasts.

Front 13

What does the Calvin Cycle make?

Back 13

Triose phosphate from CO2 and ribulose biphosphate.

Front 14

What does the diagram look like which shows the Light independent Reaction?

Back 14

Pic

Front 15

Describe the light independent reaction

Back 15

1 - CO2 from the atmosphere diffuses into the leaf through the stomata and dissolves in the water surrounding the mesophyll cells.

2 - CO2 diffuses through he plasma membrane, cytoplasm and chloroplast membranes into the stroma.

3 - Once in the stroma the CO2 combines with the compound ribulose biphosphate using an enzyme.

4 - the combination of Ribulose Biphosphate and CO2 produces x2 3 carbon, Glycerate-3-phosphate.

5 - ATP and NADPH from the light dependant reaction are used to reduce the activated Glycerate-3-phosphate, into Triose Phosphate.

6 - The NADP is reformed and goes back tot he light dependant reaction, ready to be re- reduced by accepting hydrogen.

7 - 1/6 of the Triose Phosphate is converted into useful substances i.e glucose.

8 - Most of the Triose Phosphate 5/6 is used to regenerate ADP and Pi from ATP to be used again in the light dependant reaction.

Front 16

What is Cyclic Photophosphorylation?

Back 16

This does not produce NADP OR O2 this reaction only produces small amounts of ATP. It's called cyclic because electrons from the chlorophyll are not passed onto NADP instead are passed back to PS1 via electron carriers. The electrons are recycled, only repeatedly flow through PS1.

Front 17

How many times does the Calvin Cycle need to occur to make a hexose sugar?

Back 17

The Calvin cycle needs to occur 6 times to produce a hexose sugar. Whilst producing 18 ATP and 12 red NADP.

Front 18

What are the three factors which effect the rate of Photosynthesis?

Back 18

Light, temp and CO2 conc.

Front 19

DONT FORGET TO LOOK AT GRAPHS FOR PHOTOSYNTHESIS!!

Front 20

In which part of a chloroplast does the light-independent reaction occur?

Back 20

stroma

Front 21

Describe how NADP is reduced in the light-dependent reaction of photosynthesis.

Back 21

electrons;

from chlorophyll / photolysis;

Front 22

Explain the rise in the amount of ribulose bisphosphate after the carbon dioxide

concentration is reduced.

Back 22

less used to combine with carbon dioxide /

less used to form glycerate 3-phosphate;

Front 23

Reduced NADP produced during the light-dependent reactions of photosynthesis is used

in the light-independent reactions. Explain how.

Back 23

reduction/described;

of GP to triose phosphate;

Front 24

how the energy of light is converted into chemical energy in the light-dependent

reactions.

Back 24

Electrons raised to higher energy level/electrons excited;

Use of electron carriers/cytochromes/acceptors;

For production of ATP

Front 25

Describe the part played by chlorophyll in photosynthesis.

Back 25

light (energy) absorbed by chlorophyll;

raises energy level of electrons / electrons are excited/emitted;

ATP formed;

Front 26

Describe the light-independent reactions of photosynthesis and explain how they allow the

continued synthesis of hexose sugars.

Back 26

1 5C/RuBP combines with CO

2

;

2 to form 3C compound / TP / GP;

3 using ATP;

4 and reduced NADP / eq;

5 2 molecules of 3C compound/ TP / GP form hexose;

6 all RuBP is regenerated;

7 10 molecules of 3C/TP/GP form 6 molecules of 5C/RuBP;

Front 27

Describe the role of electron transport chains in the light-dependent reactions of

photosynthesis.

Back 27

1 electron transport chain accepts excited electrons;

2 from chlorophyll / photosystem;

3 electrons lose energy along chain;

4 ATP produced;

5 from ADP and Pi;

6 reduced NADP formed;

7 when electrons (from transport chain) and H combine with NADP;

8 H from photolysis;