Photosynthesis

Question 1

Give the equation for photosynthesis.

Answer 1

6CO2 + 6H2O -> C6H12O6 + 6O2

Question 2

What is the first stage of photosynthesis called?

Answer 2

The light dependent reaction.

Question 3

Where does the 1st stage of photosynthesis take place?

Answer 3

The thylakoid membrane

Question 4

Light dependent reaction leads to the production of which molecule and the occurrence of what process?

Answer 4

ATP
Photolysis of water

Question 5

Light energy is absorbed by what pigment in the chloroplast?

Answer 5

Chlorophyll

Question 6

Absorption of light into the chloroplast does what to electrons?

Answer 6

Excites the electrons into a higher energy level

Question 7

Name the process where electrons in the LDR are released as a result of excitation.

Answer 7

Photoionisation

Question 8

After electrons have been released in the LDR, where do they travel to?

Answer 8

An electron acceptor at the start of the ETC.

Question 9

Attachment of electrons to an electron carrier does what to the electron carrier in the LDR?

Answer 9

The electron carrier becomes reduced.

Question 10

A series of what type of reactions pass electrons down the ETC during the LDR?

Answer 10

Redox

Question 11

Why do electrons lose energy as they are passed down the ETC in the LDR?

Answer 11

Each electron carrier is at a slightly lower energy level, so electrons lose energy

Question 12

Where does energy come from to be used for ATP production in the LDR?
What is the name for this type of ATP production?

Answer 12

Energy lost as electrons are passed down the chain is used to provide energy for ATP production.
This is called photophosphorylation

Question 13

What does chemiosmotic theory explain?

Answer 13

Mechanism of ATP production

Question 14

In chemiosmosis, how do H+ get into the thylakoid from the stroma?
Name the pumps used

Answer 14

Active transport, using proton pumps.

Question 15

Why does the concentration of H+ ions increase in the thylakoid during chemiosmosis?
Where in the chloroplast will have high/low concentration of H+?

Answer 15

Photolysis of water produces H+. This means that there is a high concentration of H+ in the thylakoid and a low concentration in the stroma.

Question 15

Energy for active transport of H+ in chemiosmosis comes from where?

Answer 15

Photolysis of water, when electrons are released.

Question 16

In chemiosmosis, how do protons cross the thylakoid membrane?

Answer 16

Through ATP synthase channels

Question 17

How does movement of H+ through ATP synthase channels lead to the catalysing of ADP + Pi?

Answer 17

Movement of H+ leads to the protein changing shape, therefore catalysing the reaction.

Question 18

For chlorophyll to be able to continue absorbing light, what must happen?

Answer 18

Electrons must be replaced

Question 19

Where do replacement electrons for the chlorophyll come from after some electrons have left the chlorophyll to travel down the ETC?

Answer 19

Replacement electrons come from when water is photolysed (split using light).

Question 20

Give an equation for the photolysis of water.

Answer 20

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

Question 21

Protons generated in photolysis pass out of which component of the chloroplast through what type of channels?

Answer 21

Protons leave the thylakoid through ATP synthase channels.

Question 22

Protons that have left the thylakoid during photolysis are picked up by which coenzyme?

Answer 22

NADP, which becomes reduced NADP

Question 23

Reduced NADP acts as a source of what type of energy for the plant?

Answer 23

Chemical energy

Question 24

Reduced NADP enters the light independent reaction after photolysis, carrying what?

Answer 24

Electrons that have come from the original chlorophyll molecule.

Question 25

What is another name for the light independent reaction?

Answer 25

The Calvin Cycle

Question 26

The light independent stage occurs in which part of the chloroplast?

Answer 26

The stroma.

Question 27

The light independent stage uses which 2 molecules from the light dependent stage?

Answer 27

Reduced NADP and ATP

Question 28

What is the first stage of the light independent reaction called?

Answer 28

Carbon fixation

Question 29

Describe the structure of ribulose biphosphate.

Answer 29

5C with 2 phosphate groups attached

Question 30

How many CO2 molecules are inputted into the Calvin cycle?

Answer 30

3

Question 31

Rubisco catalyses the reaction between which molecules?

Answer 31

Ribulose biphosphate and CO2

Question 32

What is rubisco short for?

Answer 32

Ribulose bisphosphate carboxylase

Question 32

How many carbons are in the molecule produced after the reaction between ribulose biphosphate + CO2

Answer 32

6

Question 33

Why does the product formed from ribulose biphosphate + CO2 immediately split into 2? What is the product called?

Answer 33

The 6C biphosphate molecule is unstable. Therefore, it splits into 2 glycerate-3-phosphate molecules.

Question 34

What is the second stage of the light independent reaction called?

Answer 34

Reduction

Question 35

In the LIR, glycerate-3-phosphate reduces into what molecule? Which molecules assist this?

Answer 35

Triose phosphate. This is done with the help of reduced NADP, which becomes oxidised, and ATP which releases it's phosphate.

Question 36

How many ATP involved in the reduction stage? How many NADPH?

Answer 36

6ATP 6NADPH

Question 37

What is the 3rd stage of the LIR called?

Answer 37

Regeneration

Question 38

How many turns of the Calvin cycle are needed to produce 1 glucose molecule?

Answer 38

6

Question 39

What happens to the triose phosphate in the regeneration stage of the Calvin cycle?

Answer 39

It's recycled

Question 40

How much ATP is used in the regeneration stage of the Calvin cycle?

Answer 40

3

Question 41

How is ribulose biphosphate regenerated at the end of the Calvin cycle?

Answer 41

ATP turns remaining triose phosphate molecules into ribulose biphosphate.

Question 42

Thylakoid membranes provide a large SA for the attachment of what 3 things?

Answer 42

Chlorophyll molecules Electron carriers Enzymes

Question 42

Name 2 adaptations do the grana membranes have for photosynthesis.

Answer 42

Many ATP synthase channels Selectively permeable

Question 43

Why do chloroplasts contain DNA and ribosomes?

Answer 43

To quickly synthesise proteins required for photosynthesis

Question 44

What does the stroma contain that is needed for the light independent reaction?

Answer 44

Enzymes

Question 45

What are the benefits of the stromal fluid surrounding the grana for the light independent reaction?

Answer 45

Short diffusion pathway for diffusion of products into the stroma.