photosynthesis (unit 2)

photosynthesis

a process by which plants make their own food using light

Location of photosynthesis

chloroplasts / palisade mesophyll

chemical

chlorophyll

Role of photosynthesis

• produces food

• produces oxygen

• removes carbon dioxide

chemical equation for photosynthesis

6CO2 + 6H2O —→ C6H12O6 +6O2

Absorption of light

chlorophyll is made up of many different pigments. Each absorbs a wavelength of light , green/ yellow light is not absorbed

how do humans increase the rate of photosynthesis (greenhouse)

• artificial light

• increase CO2 concentration

• suitable temperature for enzyme activity

light stage pathway one

• light energy is absorbed by chlorophyll and energises electrons

• electrons pass from electron acceptor to electron acceptor, releasing energy

• this energy combine with ADP+P to form ATP

• the electron returns to original chlorophyll

light stage pathway 2

• light energy is absorbed by chlorophyll and energises electrons

• two electrons pass from electron acceptor to electron acceptor releasing energy

• this combine with ADP+P to form ATP

• electrons are taken up by NADP

• water is split by light forming H+, electrons and oxygen

• hydrogen combines with NADP to form NADPH

photolysis

water is split by light to form H+, electron and oxygen

fates of the products of photolysis

• 2H+ - convert NADP to NADPH

• 2E- - sent to the electron acceptor

• ½ O2 - used in respiration

location of dark stage

stroma of chloroplasts

fate of ATP

used in the dark stage

fate of oxygen

used in respiration/ let into atmosphere

fate of NADPH

used in the dark stage

dark stage steps

• co2 is converted to glucose

• ATP breaks down to ADP+P releasing energy

• NADPH breaks down NADP+ 2e+ H- used to make glucose

• NADP+ and ADP+P are returned to the light stage