C17 - Photosynthesis

Question 1

Why do you living organisms need energy

Answer 1

Active transport
DNA replication
Cell division
Protein synthesis

Question 2

What is the enzyme that hydrolyses ATP

Answer 2

ATPase

Question 3

What is the enzyme that synthesises ATP and what are its reactants

Answer 3

ATP synthase, ADP and Pi

Question 4

Why is ATP a good source of energy

Answer 4

Small quantities of energy – efficient
Easily hydrolysed – single step reaction
Small and soluble – easily transported

Question 5

Give two ways chloroplasts are adapted for function

Answer 5

Network of membranes – high surface area – max absorption of light
Contain photosynthetic pigment to absorb light

Question 6

What are the flattened membraneous sacks in chloroplasts called and what are their stacks called

Answer 6

Thylakoids

Grana

Question 7

What are lamellae

Answer 7

Membranes that join Grana

Question 8

What is the fluid in chloroplasts called

Answer 8

Stroma

Question 9

What is chlorophyll and what is its function

Answer 9

Photosynthetic pigment
Absorbs specific wavelengths of light
Absorbs red and blue, reflects green

Question 10

name one primary and one accessory photosynthetic pigment and where they are located

Answer 10

Primary – chlorophyll a in reaction centre

Secondary chlorophyll b in thylakoid membrane

Question 11

What is the role of accessory pigments

Answer 11

Absorb maximum light by absorbing a range of colours

Question 12

What is the difference between photosystem i and photosystem II in the light dependent reaction

Answer 12

Photosystem I I – lower energy level, first photosystem – noncyclic phosphorylation
Photosystem I - second, higher energy level

Question 13

What are the three steps in the light dependent reaction

Answer 13

Photoionisation of chlorophyll
Synthesis of ATP
Photolysis of water

Question 14

What happens in the photoionisation of Chlorophyll

Answer 14

PSII absorbs light energy
Energy causes electrons to become excited, with sufficient energy they leave
High energy electrons pass along electron transport chain
Energy released used to pump H+ ions across the thylakoids membrane

Question 15

How is ATP is synthesised in the light dependent reaction

Answer 15

Chemiosmosis causes flow with H+ ions across thylakoid membrane
Ions cause a conformational change
ATP synthase synthesise ATP from ADP and PI

Question 16

Where do the electrons to replace those lost in PS1 come from

Answer 16

End of electron transport chain from PS I I

Question 17

Where do electrons come from to replace those lost in psII

Answer 17

Photolysis of water

Question 18

Where do electrons go after being passed down PSI transport chain

Answer 18

Combined with H+ and NADP to make NADPH

Question 19

What happens in the photolysis of water

Answer 19

Water split into H+, e- and O2 using energy from sun

Question 20

Describe the process of cyclic phosphorylation

Answer 20

Energy from the Sun absorbed by psi
Electrons excited, passed along electron transport chain
Given back to psi
Energy released used for chemiosmosis and synthesis of ATP

Question 21

What word describes the loss of electrons from chlorophyll when A light shines on it

Answer 21

Photoionisation

Question 22

What stages is the light independent stage of photosynthesis made of

Answer 22

Calvin cycle
One – CO2 fixation
Two – reduction of GP
Three – regeneration of RuBP

Question 23

What happens in CO2 fixation in the Calvin cycle

Answer 23

CO2 enters
RuBP (5C) fixes to C in CO2
Carboxylation reaction
Catalysed by RuBP

Question 24

What happens during reduction of GP in the Calvin cycle

Answer 24

GP to TP
Uses energy from ATP—> ADP +Pi
Uses H+ from NADPH—> NADP

Question 25

What happens during the regeneration of RuBP in Calvin cycle

Answer 25

TP (6C) to RuBP (5C) +C C goes to forming organic molecules (eg. Glucose) Uses energy from ATP—> ADP +Pi

Question 26

What are the uses of glucose

Answer 26

``` Substrate for aerobic respiration Cellulose production Store amylase and amylopectin Make sucrose Stored as lipids Make amino acids and proteins Synthesis of nucleic acids ```

Question 27

What are the three factors that affect the rate of photosynthesis

Answer 27

Light intensity Concentration of CO2 Temperature

Question 28

How does light intensity affect the rate of photosynthesis

Answer 28

Needed for ATP and NADPH production in light dependent reaction

Question 29

How does the concentration of CO2 affect the rate of photosynthesis

Answer 29

Needed for carbon fixation in Calvin cycle

Question 30

How does temperature affect the rate of photosynthesis

Answer 30

Affects rate of enzyme controlled reactions (e.g. carbon fixation and RuBP) However too hot and will denature

Question 31

Is water a factor that will affect the rate of photosynthesis

Answer 31

No. Although water is required it is never considered a limiting factor because the stomata will have closed so no CO2 will be able to enter

Question 32

How will reducing light intensity affect the concentration of the products in the Calvin cycle

Answer 32

Increased GP | Reduced RuBP and TP (ATP needed for their synthesis coming from LDR)