Respiration and photosynthesis Flashcards
What is the structure of a chloroplast
Chloroplast envelope- this is the outer and inner membrane and it’s function is to keep the reactants for photosynthesis close to their reaction site
Thylakoids- the green pigment chlorophyll is found in thylakoids they are the site of the light dependent reaction of photosynthesis
Grana - they are stacks of thylakoids
Lamellae - they join the grana together maintaining a working distance between the grana for maximum function as efficiently as possible
What is a photo system
A photo system is a combination of the protein and the pigment in the thylakoid membrane
What is the stroma
It’s a gel like substance contained within the inner membrane. It contains enzymes, sugars etc for the light dependent reaction
What wavelengths of light can a plant best absorb
Blue and red light
What does the action spectrum show
It shows the volume of oxygen produced
Why do most plants appear green
Because the green wavelength isn’t being absorbed as much so it is being reflected
What is the compensation point
Where the rate of photosynthesis and respiration are equal
Why do plants have several pigments
It allows the plant to absorb more of the light in a wider range of wavelengths than a single pigment would be able to
What is phosphorylation
This is when phosphate is added to a molecule
What is photolysis
This is the splitting of water molecules using light
What is light energy used for when it is absorbed by the photosynthetic pigments
It’s used to:
- add a phosphate group to ADP to form ATP
- Form reduced NADP
What are ATP and reduced NADP used for in the light dependent reaction
ATP is used to provide energy for the Calvin cycle and reduced NADP transfers hydrogen to the Calvin cycle
What happens to water when light hits the plant
Water is oxidised to form protons (H+), electrons and oxygen which is mostly lost through the stomata but some is used for aerobic respiration
What is photophosphorylation
Adding a phosphate group to a molecule using light energy
What is a coenzyme
A molecule (e.g NADP) that aids the function of an enzyme
What are the 4 stages of non cyclic photophosphorylation
Stage 1
- light energy is absorbed by photsystem II
- The light energy excites electrons in the chlorophyll
- the electrons move to a higher energy level
- they move along the electron transport chain to photosytem I
Stage 2
- as excited electrons leave PSII they must be replaced
- light energy splits water into protons, electrons and oxygen
Stage 3
-the excited electrons lose energy as they pass the electron transport chain this energy is used to produce ATP from ADP and Pi
Stage 4
-Light energy is absorbed by PSI which excites the electrons again to an even higher energy level
- finally the electrons are transferred to NADP to form reduced NADP
What is chemiosmosis
The process where movement of protons across a membrane generates atp
What happens in the process of cyclic photophosphorylation
- The electrons go back to PSI instead of NADP this means that electrons are recycled and can repeatedly flow through PSI
- this produces a little bit of atp but no oxygen or reduced NADP
Where does the Calvin cycle take place in the chloroplast
The stroma
What is the first stage of the Calvin cycle
- Carbon dioxide is combined with ribulose bisphosphate (RuBP) to form two molecules of glycerate 3 phosphate (GP)
- Carbon dioxide combines with RuBP and the carbon dioxide is said to be fixed so this is carbon fixation
- this reaction is catalysed by the enzyme rubisco
What is the second stage of the Calvin cycle
- atp from the light dependent stage provides energy for the 3 carbon compound GP to be reduced into GALP another 3 carbon compound
- this reduction requires h+ ions which come from reduced NADP
- reduced NADP is then recycled to oxidised NADP
- GALP then gets converted into different useful compounds
What is the third stage of the Calvin cycle
- 5 of the 6 GALP produced in the cycle are used to regenerate RuBP to continue the Calvin cycle
- this regenerating requires ATP
What are the products of the Calvin cycle
Carbs, lipids, proteins and nucleic acids
How are carbs formed from the Calvin cycle
Two GALP molecules are joined together which is known as gluconeogensis
