photosynthesis Flashcards
Autotrophs
They sustain themselves without eating anything derived from other organisms
They are the ultimate source of organic compounds and are therefore known as producers.
Heterotrophs
Live on compounds produced by other organisms and are known as consumers.
They depend on photosynthesis for food and oxygen
What are the specific sites of photosynthesis in a plant cell?
Chloroplasts
Describe the structure of the chloroplast
An envelope of two membranes encloses the stroma, which is in a dense fluid-filled area. Within the stroma is a vast network of interconnected membranous sacs called thylakoids - they segregate the stroma from thylakoid space. They set up compartments separate from the stroma - this will allow the proton gradient to be established.
Chlorophyll is located in the thylakoid membranes and is the light-absorbing pigment that drives photosynthesis and gives plant their green colour.
What are stomata?
The tiny poles that the exterior of the lower epidermis of a leaf contains.
Reaction for photosynthesis?
6CO2+ 6h2o + light energy = c6h12o6 + 6o2
Describe the two stages of photosynthesis
The light reactions occur in the thylakoid membranes where solar energy is converted to chemical energy. The net products of the light reactions are NADPH (which stores electrons), ATP and oxygen.
The primary events:
1. The light energy is absorbed by chlorophyll, which drives the transfer of electrons from water to NADP+, forming NADPH.
2. Water is split during these reactions and o2 is realsed.
3. ATP is generated, using chemiosmosis to power the addition of a phosphate group to ADP, a process called photophosphorylation.
The Calvin cycle occurs in the stroma, where co2 from the air is incorporated into organic molecules in carbon fixation. The Calvin cycle uses the fixed carbon plus NADPH and ATP from the light reactions in the formation of new sugars.
