A2 Photosynthesis and Respiration Flashcards
What is the Equation for Photosynthesis?
6CO2 + 6H2O + Energy > C6H12O6 + 6O2
What is the Equation for Aerobic Respiration?
C6H12O6 + 6O2 > 6CO2 + 6H2O + Energy
What Properties of ATP make it a Good Energy Source?
- Releases small, manageable amount of energy, no energy wasted as heat
- Small, soluble molecule, easily transported
- Easily broken down, energy released quickly
- Quickly re-made
- Can make other molecules more reactive by transferring one of its phosphate groups
- ATP cant pass out cell, always has immediate supply of energy
Define phosphorylation and photophosphorylation
Adding phosphate to a molecule (using light)
Define Photolysis
The splitting of a molecule using light energy
Define photoionisation
When light energy ‘excites’ electrons in an atom or molecule, giving them more energy, causing them to be released. Atom becomes a positively-charged ion
Define decarboxylation and dehydrogenation
Decarboxylation - removal of CO2 from a molecule
Dehydrogenation - removal of H from a molecule
Describe redox reactions
Reduction:
- Gained electrons and may have gained hydrogen or lost oxygen
Oxidation:
- Lost electrons and may have lost hydrogen or gained oxygen
Oxidation of one molecule always involves reduction of another
Describe what a Co-enzymes is and their Involvement in Photosynthesis and Respiration
Molecule that aids the function of an enzyme by transferring a chemical group from one molecule to another
Photosynthesis:
- NADP - transfers hydrogen from one molecule to another, it can reduce or oxidise a molecule
Respiration:
- NAD/FAD - same as NADP
- Coenzyme A - transfers acetate between molecules
Describe the Structure of a Chloroplast
- Flattened organelles surrounded by double membrane
- Thylakoids stacked into grana
- Grana linked together by lamellae
- Photosynthetic pigments contained in thylakoid membranes, attached to proteins
- Protein and pigment called a photosystem
- Stroma contains enzymes, sugars and organic acids
- Carbohydrates stored as starch grains in stroma
What are the Products of the Light-Dependent Reaction?
- ATP made from ADP and inorganic phosphate
- Reduced NADP made from NADP
Describe the First Stage of the Light-Dependent Reaction (Photoionisation)
- Light energy absorbed by PSII
- Excited electrons in chlorophyll move up to higher energy level
- Electrons released from chlorophyll, move down ETC to PSI
Describe the Second Stage of the Light- Dependent Reaction (Photolysis)
- Electrons leaving PSII need replacing
- Light energy splits water into Protons (H+), electrons and oxygen
- H2O > 2H+ + 0.5O2
Describe the Third Stage of the Light-Dependent Reaction (Chemiosmosis)
- Electrons lose energy as they move down ETC
- Energy used to transport protons into thylakoid, higher conc. of protons than stroma
- Forms proton gradient across membrane
- Protons move down conc. gradient into stroma via ATP synthase, embedded in thylakoid membrane
- Energy from this combines ADP and inorganic phosphate to form ATP
Describe the Fourth Stage of the Light-Dependent Reaction (Reduced NADP)
- Light energy absorbed by PSI, excites electron to even higher energy level
- Electrons transferred to NADP, along with a proton from stroma
- Forms reduced NADP