Photosynthesis

Question 1

Which ptotosystem appears first in the sequence of the light dependent reactions? [1]

Answer 1

Photosystem 2

Question 2

Explain why the word equation of photosynthesis is not accurate of the whole process [1]

Answer 2

Implies that is a single step reaction and other products are also made

Question 3

What is required to excite 2 electrons from photosystem 2? [1]

Answer 3

Photon of visible light

Question 4

Give the word and symbol equation for photolysis [2]

Answer 4

Water –> Electrons + Oxygen + Hydrogen ions

H20 -> 2e- + 1/2O2 +2H+

Question 5

Define the term photolysis [1]

Answer 5

The splitting of a molecule of water of water using visible light

Question 6

When NADP is reacted with two electrons and two protons it becomes what? [1]

Answer 6

Reduced NADP or NADPH

Question 7

What is the main difference between cyclic and non cyclic photo-phosphorylation? [2]

Answer 7

Non cyclic requires an external source of electrons whereas cyclic can keep using the same electrons over and over again

Question 8

Draw out the stages of the light dependent reactions [4]

Answer 8

Check diagram in pack

Question 9

State the reaction of chemeosmosis [1]

Answer 9

ADP + Pi -> ATP

Question 10

Where does the energy require for chemeosmosis come from [1]

Answer 10

Energy given of at the electron transport chain

Question 11

Where within the chloroplast does the light dependent stage take place? [1]

Answer 11

Within the thylakoid membrane

Question 12

What is the initial reactant involved in the light independent reactions? [1]

Answer 12

RUBP

Question 13

What does RUBP stand for? [1]

Answer 13

Ribulose biphosphate

Question 14

What is the function of the rubisco enzyme? [1]

Answer 14

To fix CO2 to RUBP

Question 15

Suggest where the CO2 for the fixing comes from? [1]

Answer 15

The air

Question 16

What is the enzyme that fixes CO2 to RUBP called? [1]

Answer 16

Rubisco

Question 17

After fixing CO2 and RUBP form what? [1]

Answer 17

GP

Question 18

Why isn’t GP very useful? [2]

Answer 18

Very unstable so breaks apart easily

Question 19

What does GP stand for? [1]

Answer 19

Glycerate (III) Phosphate

Question 20

How does GP form TP? [2]

Answer 20

H+ donated from NADPH and energy required in the form of ATP

Question 21

What does TP stand for? [1]

Answer 21

Triose phosphate

Question 22

What happens to the majority of TP? [1]

Answer 22

It is phosphorylated and regenerates RUBP

Question 23

What happens to the minority or TP? [1]

Answer 23

Used within the plant to form amino acids, sugars and lipids.

Question 24

The light independent reactions are more commonly known as the what? [1]

Answer 24

Calvin - Benson cycle

Question 25

Expalin what is meant by CO2 fixation? [2]

Answer 25

The conversion of a gaseous molecule into an organic compound

Question 26

At what point in the Calvin cycle is there a reduction reaction taking place? [1]

Answer 26

GP is reduced when it gains e- from NAPDH in order to form TP

Question 27

How many times must the cycle go around for one molecule of glucose to be produced? [1]

Answer 27

6

Question 28

Explain why the light independent reactions could not carry on for a very long time without any light? [1]

Answer 28

Because you would run out of ATP and NADPH both of which are produced in the LDR so light needed in order for this to occur

Question 29

Draw out the Calvin cycle [4]

Answer 29

See diagram in pack

Question 30

List the three factors that limit the rate of photosynthesis [3]

Answer 30

Light intensity Carbon dioxide concentration Temperature

Question 31

Suggest why temperature in a limiting factor? [2]

Answer 31

Because the greater the temperature the more Ke therefore the rate of enzyme controlled reactions is increased (CO2 fixation in the presence of rubisco

Question 32

Suggest why CO2 concentration is a limiting factor? [2]

Answer 32

Because CO2 is required to be fixed to RUBP. The more CO2 the more GP can be produced so the Calvin cycle proceeds at a greater rate.

Question 33

A horizontal line on a rate / factor x suggests what? [1]

Answer 33

Another factor - not x - is limmiting

Question 34

What abbreviation can be used for concentration? [1]

Answer 34

[]

Question 35

The light compensation point is what? [2]

Answer 35

The point at which there is no net CO2 uptake. I.e the CO2 produced in respiration = the CO2 used in photsynthesis

Question 36

The light saturation point is what? [2]

Answer 36

The value of light intensity which gives the maximum rate of photosynthesis