9. Photosynthesis Flashcards
Def. of photosynthesis
The way in which plants make their food using light energy
Photosynthesis equation
6CO2 + 6H2O —–Light+Chlorophyl—> C6H12O6 +6O2
Role of photosynthesis
Source of O2 for living things
Makes food for plants
Makes food for animals
Where photosynthesis takes place
Chloroplast
Name stage 1
Light dependent stage
Where does stage 1 happen
Granium of the chloroplast
Products of stage 1
ATP, NADPH, O2
Fate of products from stage 1
ATP- used in dark stage to provide energy to reduce H+, e- and CO2 to form glucose
NADPH- Provides H+ and e- to reduce CO2
O2- released as gas (wasted) or used in respiration
Photolysis
- means
- what
- where
- how
- means: photo=light, lysis= burst
- what: water splitting in light dependent stage
- where: In the chloroplast of the leaf
- how: energy from the sun
What is the reaction centre chlorophyll
Is the molecule that specifically absorbs the light energy
Sources of things needed for photosynthesis
CO2, H2O, Light
CO2- air, respiration, burning fossil fuels
H2O- absorbed through roots from soil
Light- Sunshine
What is chlorophyll
Green pigment in leaf used to absorb light energy
Name stage 2
Light independent stage / dark stage/ Calvin cycle
Where does stage 2 happen
Stroma of chloroplast
Products of second stage
Glucose (C6 H12 O6)
ADP
NADP
Fate of products from stage 2
Glucose (C6 H12 O6)- glucose used as food/ used in respiration/ stored as starch
ADP- will go back to stage 1 to be phosphorylated
NADP- will go back to stage 1 to gain H+ and e-
Describe process in stage 1
Start
Light energy absorbed by chlorophyll in chloroplast.
Electrons become energised and leave chlorophyll in pairs.
Picked up by 2 pathways.
Pathway 1
Pathway 2
Describe Pathway 1 in stage 1
Name and what happens
Pathway 1: Cyclic photo phosphorylation
Electrons picked up by electron acceptor which passes them into a carrier system, C1-C2-C3, releases energy at each stage which is used to make ATP
Describe pathway 2 (stage 1)
Name and what happens
Pathway 2: Non cyclic photo phosphorylation
The 2 electrons join with the NADP+ to make NADP-
A water molecule splits to make H+, e-, O2
The H+ joins with the NADP- to form NADPH
The electron passes into a carrier system releasing energy to form ATP and returns to the chlorophyll (reaction centre)
Describe Stage 2
NADPH releases electron(e-) and hydrogen molecule (H+)
An ATP from stage 1 is carried over and loses a phosphate and releases energy (ATP=ADP+ P)
The e- and H+ reduces the CO2 with energy from the ATP and forms glucose
