Photosynthesis Flashcards
How does Light Dependent Reaction occur?
Photoionisation of reaction centre photosynthetic pigments due to the absorption of light energy supplies excited electrons
These are replaces by photolysis of water
Excited electrons travel down an electron transport chain and transfer some of their energy to create a proton gradient across the thylakoid membrane
The energy in the proton gradient is used to produce ATP
Excited electrons and hydrogen ions are used to reduce NADP
What is an Autotroph and what are the examples of it?
Carry out photosynthesis and use simple inorganic molecules to synthesise complex organic molecules such as glucose.
Examples: plants and algae
What are Heterotrophs and what are some examples of it?
Organisms which obtain molecules by digesting and absorbing complex organic molecules - organic molecules used for growth and respiration
Examples: animals and fungi
Where does light dependent stage occur?
Thylakoid
What’s the equation for photosynthesis?
6CO2 + 6H20 ——> C6H12O6 + 6O2
What are photosynthetic pigments? Some examples of it?
Chemicals that absorb light energy, found in the thylakoid membrane of chloroplasts, absorbs light of a particular range or wavelengths of light energy
Examples: Chlorophyll A, Chlorophyll B, Carotene and Xanthophyll
What are accessory pigments?
They surround the primary pigment and absorb light energy and pass the energy from one to another and then onto the primary pigment
Example: Carotenoids
What are primary pigments?
Reaction centres where electrons are excited to higher energy levels during the light dependent reaction
Example: Chlorophyll A
What is photolysis of water?
Because electrons have been lost from chloroplast due to photoionisation, these electrons are replaced by water. Water molecules are slit using light energy to produce protons, electrons and hydrogen ions. Protons are used in chemiosmosis.
What are coenzymes?
Molecule that aids the function of an enzyme. Works by transferring a chemical group from one molecule to another. Example is NADP
Non-cyclic photosphorylation?
PSII and PSI are linked through a series of protein electron carriers on the thylakoid membrane forming electron transport chain. Electrons move from PSII to PSI, as they do so energy is lost as each electron becomes reduced and oxidises as it moves. This energy is used to add phosphate to ADP to form ATP and reduce the co-enzyme NADP to reduced NADP
What does non-cyclic photophosphorylation produce?
ATP, NADP, O2
What is Chemiosmosis?
As electrons flow down the electron transport chain from PSII to PSI, some energy is used to actively transport H+ ions into the thylakoid space which produces a proton gradient. Protons move down the concentration gradient into the stroma through ATP synthase. Energy from the movement is used to form ATP
What is cyclic phosphorylation?
Does not involve PSII. Electrons in PSI pass through in a circle to produce ATP not reduced NADP. Electrons are passed back to PSI via electron carriers
What is the energy resulting from LDR used for?
- ) Making ATP from ADP and inorganic phosphate
- ) Reduced NADP from Oxidised NADP
- ) Photolysis - into protons, electrons and oxygen
