Topic 9- Photosynthesis Flashcards
What are the organisms that do photosynthesis
They are called Photoautotrophs
- plants
-multicellular algae
-unicellular eukaryotes
-cyanobacteria
-purple sulfur bacteria
What are the important structures for photosynthesis
Mesophyll- sack of chloroplast
Chloroplast- where photosynthesis happens
stomata- pores in the leaves which allow CO2 to enter and O2 to leave
What is the redox reaction that happens in photosynthesis?
Energy+CO2+H2O becomes G3P and Oxygen
How does light absorption work
The color of the object absorbs the opposite color of light. Plants absorb purple light cause it has the most energy thus it is green.
How do plants collect the suns energy?
Chlorophyll collects the light and transfers the energy to the electrons.
What is photorespiration?
When rubisco takes oxygen and tries to use it in the Calvin Cycle to make a complex carbon chain which is bad because it is using energy to make garbage. This happens when the stomata is closed and CO2 cannot enter.
What is C3 Photosynthesis
Regular photosynthesis
What is C4 photosynthesis? When is this likely to occur?
Leaves have evolved a second layer called the bundle sheath where photosynthesis happens. The mesophyll is used to store C4. When it is needed the C4 is converted back to CO2 for photosynthesis. Likely to happen in hot climates when the stomata closes in the afternoon
What is CAM photosynthesis and when does it happen.
Plants leave stomata open at night to convert CO2 into C4 and does photosynthesis in the day. Often happens in extremely hot climates.
Describe the stages of photosynthesis
- Light Reactions
Occurs in the Thylakoid membrane and turns light energy into chemical energy to power the Calvin Cycle. - Calvin Cycle
Takes place in the stroma and its goal is to use ATP and NADPH to make G3P from CO2.
Describe light reactions in photosynthesis
a. Photon of light hits a chlorophyll in photosystem 2. The chlorophylls transfer the energy from one to another until it reaches the central chlorophyll pair which is really electronegative and gives the energy to an electron.
b. Energized electron is grabbed by a primary electron acceptor and used for work by being send through a small transport chain to create an electrochemical gradient by pumping protons into thylakoid space. This then powers ATP synthase to make ATP.
c. Meanwhile that electron is replaced by one from H2O, which releases H+ and Oxygen.
d. depleted electron goes to photosystem 1 and is re energized
e. It is then taken by a primary electron acceptor and used to power NADP+ reductase enzyme to make NADP+ into NADPH.
Describe the Calvin cycle in photosynthesis.
a. Carbon Fixation- Rubisco attached 3 co2 from the air onto 3 RuBP causing it to break into a 2 carbon chain.
b. Reduction- uses energy from ATP and NADPH to energize the 3 carbon chain into G3P.
c. Only one of the G3P are taken out of the system, the remaining 5 get turned back into RuBP.
