5.2.1 Photosynthesis

Question 1

What parts of a chloroplast make it efficient for photosynthesis?

Answer 1

Large SA for max absorption
Thylakoids contain lots of pigments
Stroma is a chemical reaction site

Question 2

What is the definition of a pigment?

Answer 2

Absorb different wavelengths of light

Question 3

Why are leaves green?

Answer 3

Chlorophyll a pigment in stroma

Question 4

Why is it good to have a range of pigments for photosynthesis?

Answer 4

• Each pigment absorbs different wavelengths of light
• Allows for a broader range of light to be absorbed

Question 5

Where is chlorophyll B found?

Answer 5

The Thylakoids

Question 6

What is the light dependent stage?

Answer 6

The first stage of photosynthesis where energy is harvested for light

Question 7

What is the purpose of the light dependent stage?

Answer 7

To use energy to split water
To create ATP and NADPH

Question 8

What are the four key steps of the light dependent stage?

Answer 8

• Non cyclic photophosphorylation
• Cyclic photophosphorylation
• Photolysis
• Chemiosmosis

Question 9

Whuch photosystem is used first in non-cyclic photophosphorylation?

Answer 9

• Photosystem 2 at 680 nm

Question 10

How are electrons moved along from photosystems in non cyclic phosphorylation?

Answer 10

Electron transport chain

Question 11

How are electrons that are used up replaced in non cyclic phosphorylation?

Answer 11

Photolysis

Question 12

What happens at the end of non cyclic photophosphorylation?

Answer 12

Electrons are accepted by NADP along with a H+ from photolysis forming NADPH

Question 13

Which photosystem does cyclic photophosphorylation occur in?

Answer 13

Photosystem 1

Question 14

How does cyclic photophosphorylation occcur?

Answer 14

Not all electrons are picked up by NADPH

Question 15

What are the key differences between cyclic and non cyclic photophosphorylation?

Answer 15

Same electrons reenter system in cyclic photophosphorylation
No NADPH is made in cyclic photophosphorylation (some ATP is still made however)

Question 16

What is the formula for Photolysis?

Answer 16

H2O -> 1/2O2 + 2e- + 2H+

Question 17

What is the enzyme involved in chemiomosis?

Answer 17

ATP synthase

Question 18

How are H+ ions transported via chemiosmosis?

Answer 18

As electrons move along electron transport chain they released small amounts of energy
This energy can then actively transport H+ out

Question 19

What happens to the protons at the end of chemiosmosis?

Answer 19

Combine with NADP to form NADPH
Provide energy for photophosphorylation of ADP

Question 20

Where does the light independent reaction occur?

Answer 20

In the stroma

Question 21

What is the key enzyme involved in the calvin cycle?

Answer 21

RuBisCo

Question 22

What are the reactants and products of the light independent reaction?

Answer 22

Reactants- Carbon dioxide, NADPH, RuBP and ATP
Products- Hexose sugar

Question 23

How many cycles of the calvin cycle is it to form one hexose sugar?

Answer 23

6 cycles

Question 24

What is the first step of the light independent reaction?

Answer 24

CO2 fixed to RuBP via RuBisCo to form 2x GP

Question 25

WHat happens to GP in the calvin cycle?

Answer 25

Some reduced by NADPH to form TP
Others to form amino acids and fatty acids

Question 26

Why is only one carbon removed from each turn of the cycle?

Answer 26

So that RuBP can be regenerated