Photosynthesis

Question 1

What is formed in the light dependant reaction

Answer 1

ATP
NADPH

Question 2

Where does the light dependant reaction occur

Answer 2

the thylakoid membrane of chloroplasts

Question 3

3 stages of light dependant reaction

Answer 3

Photoionisation of chlorophyll + photolysis of water

Chemiosmosis - ATP production

NADPH production

Question 4

Photoionisation of chlorophyll and photolysis

Answer 4

Light energy from the sun passes through photosystem II and is absorbed by chlorophyll , excites an electron in chlorophyll causing it to rise to a higher energy level

therefore chlorophyll has been photoionised

The electron is replaced by the photolysis of water into oxygen electrons and protons

Question 5

Chemiosmosis in photosynthesis

Answer 5

Once the electron from photoionisation has reached the higher energy level it is transported down the electron transport chain

this causes the electron to release energy, therefore protons can enter the thylakoid space, creating an electrochemical gradient

therefore protons will pass through the ATP synthase enzyme, allowing ATP to be synthesised from ADP and Pi

Question 6

NADPH production

Answer 6

Electrons that have been passed down the ETC will be excited again and will be passed through photosystem 1 to directly reduce NADP+ to NADPH

Question 7

Where does light independent reaction occur

Answer 7

in the stroma

Question 8

Full process of the Calvin cycle

Answer 8

Carbon dioxide combines with RuBP to form a 6C molecule, which then splits to give 2 molecules of GP (3C) , this reaction is catalysed by rubisco

Both GP molecules are reduced using NADPH and ATP for energy to produce 2 molecules of TP

5 out of every 6 molecules of TP are used to regenerate RuBP, and the other molecule is used for useful organic substances ( polysaccharides or converted to glycerol)

Question 9

3 limiting factors of photosynthesis

Answer 9

Temperature - affects rate of all reactions

carbon dioxide concentration - affects rate of light independent reaction

light intensity - affects rate of light dependent reaction

Question 10

Agricultural practices to overcome limiting factors

Answer 10

Grow plants under LED lights to maximise light intensity and maintain temperature

use a greenhouse to control temperature and light intensity

Burning fuel to produce CO2