Topic 5 - Photosynthesis and Respiration Flashcards
What is the equation for photosynthesis ?
6CO2 + 6H2O = C6H12O6 + 6O2
What is photosynthesis ?
The process where energy from light is used to make glucose.
What is the equation for respiration ?
C6H12O6 + 6O2 = 6CO2 + 6H2O
What is respiration ?
The release of energy
What does anaerobic respiration in plants and yeast produce ?
ethanol and carbon dioxide
Why is ATP needed ?
cells cant get energy directly from glucose, so in respiration the energy released from glucose is used to make ATP which carries energy in cells to where it is needed.
What is a photosystem ?
A light absorbing pigment attached to a protein. it contains chlorophyll in the middle
where are the products of photosynthesis stored ?
starch grains in the stroma
What is the thick fluid in chloroplast called ?
stroma
Where does the light dependent reaction of photosynthesis take place ?
The thylakoid membrane of the chloroplast
What is the light dependent reaction of photosynthesis also called ?
Photophosphorylation
What occurs during photophosphorylation (LDR) ?
- Photoionisation: light energy is absorbed by the chlorophyll. The light energy excites electrons and they move to a higher energy level. They move down an electron transport chain and a series of redox reactions occur.
- Photolysis: These electrons must be replaced so light energy is used to split water into oxygen, protons and electrons
- Chemiosmosis: The electrons loose energy as they move down the electron transfer chain and this energy is used to transport the protons across the membrane into the thylakoid. This forms a proton gradient. Protons move down the concentration gradient by ATP synthase.
- The energy from this movement combines ADP and Pi to form ATP.
- The electrons and protons are transferred to NADP to form reduced NADP.
What is the light independent reaction also called ?
The calvin cycle
Where does the calvin cycle take place ?
The stroma of the chloroplast
What is the function of the calvin cycle ?
It makes triose phosphate which can be used to make useful compounds such as carbohydrates, lipids and proteins.
What happens during the light independent reaction
- Carbon dioxide enters the leaf through the stomata and diffuses into the stroma of the chloroplast. It is combined with RuBP ( a five carbon compound), this reaction is catalysed by rubisco. This produces an unstable 6 carbon compound which quickly breaks down into 2 molecules of a 3 carbon compound called GP
- GP is reduced into triose phosphate by reduced NADP.
- Some triose phosphate is converted into useful compounds, e.g. glucose. Some continue into the calvin cycle to regenerate RuBP which uses ATP from the LDR.