photosynthesis Paper 2

Question 1

ATP

Answer 1

Adenosine triphosphate
releases energy in small amounts, manageable amounts
broken down in a single process
immediate energy compound
phosphorylates
makes phosphorylated substances more reactive
refromed and made again

Question 2

photosynthesis

Answer 2

carbon dioxide + water –> Glucose + oxygen

Question 3

Photoionisation

Answer 3

physical process in which an ion is formed from the interaction of a photom with an atom

Question 4

photolysis- where does this occur?

Answer 4

splitting of water molecules in the presence of light into proton, electron and oxygen- in the thylakoid space

Question 5

photphosphorylation

Answer 5

the conversion pf ADP to ATP using energy of sunlight by activation of PS11

Question 6

where does the LDR take place

Answer 6

in the grana/ thylakoid membrane and results in the formation of ATP and NADPH

Question 7

LDL

Answer 7

Chlorophyll absorbs light energy, chlorophyll becomes oxidised. Excited electrons move to a higher energy level- energy released helps activate the proton pump.electrons move down ETC and are oxidised and reduced through a series of redox reactions. This pumps H+ ions to form proton gradient which moves through ATP synthase to combine ADP + Pi to form ATP. High energy electrons from next chlorophyll reduces NADP to form reduced NADP.
Photolysis- energy from light- catalyses the breakdwon of water –> 2H2O–> 4 protons, 4 electrons and O2
protons used to help activate proton carrier and proton gradient.
Electrons used to replace electrons lost from chlorophyll and reduce NADP.

Question 8

Chemiosmotic theory

Answer 8

the movement of ions across a membrane down an electrochemical gradient. This gradient is established through redox reactions and activation of proton pumps.

Question 9

In plants, ATP is produced in the light dependant reaction. Suggest why this is not the plants only source of ATP

Answer 9

Plants don’t photosynthesise in the dark
not all parts of the plant photosynthesise
plant require more ATP than is produced in the light dependant reaction
ATP used in active transport

Question 10

describe the effect of introducing a herbicide on the electron transport chain

Answer 10

reduced transfer of protons across thylakoid membrane
less ATP produced
less NADP produced
light dependant reaction is slower
less reduction of GP to Triose Phopshate

Question 10

What role does light play in the LDR

Answer 10

Photoionisation of chlorophyll- excitation of electrons to higher energy level. photolysis of water

Question 10

How is ATP produced

Answer 10

H+ electrons diffuse through ATP synthase

Question 11

How is NADP produced

Answer 11

H+ and electrons used to reduce NADP- O2 is released as a useful waste product

Question 12

LIDR

Answer 12

carbon dioxide combines with RuBP
produces two GP molecules
2GP reduced to 2x triose phosphate
using reduced NADP
using energy from ATP
Triose phosphate converted to glucose and amino acids

Question 13

Fixation, reduction and regeneration

Answer 13

F- RuBP acts as a carbon dioxide acceptor, catalyzed by rubisco. CO2 reacts with RuBP to from two molecules of GP
R- GP reduced to triose phosphate. requires NADPH and ATP. Some triose phosphate converted into useful compounds
Re- Triose phosphate mostly used to regenerate RuBP from ATP

Question 14

factors affecting rate of photosynthesis

Answer 14

temperature, CO2 conc, Light intensity and wavelength

Question 15

The conc of CO2 in the air at different heights above the ground in a forest changes over a period of 24 hours. Describe and explain these changes

Answer 15

High conc of CO2 linked with darkness
no photosynthesis in the dark
in the dark plants and other organisms respire
in light, the net uptake of CO2 by plants increases- rate of photosynthesis greater than rate of respiration
decrease in CO2 concentration with height
at ground level fewer leaves- less photosynthesis

Question 16

Greenhouses

Answer 16

enhance temp, CO2 conc and light intensity/ wavelength- allow to grow crops all year round
Artificial light used to enhance light intensity to optimum levels, blinds can be used if light intensity is too high
CO2 levels increased by burning fossil fuels or pumping in CO2
heaters can be used to raise the temperature to optimum levels