Chapter 7 Flashcards
What is the definition of photosynthesis?
It is the use of light energy to convert carbon dioxide into organic compounds (contains one or more C-H bonds) such as carbohydrates
What are autotrophs?
What is their other name?
Photosynthetic organisms that do not need to import already formed organic compounds from the environment
Photoautotrophs
What is the equation for photosynthesis?
6CO2+12H2O->C6H12O6+6O2+6H2O
What are the two processes within photosynthesis?
The Light reaction
The Calvin cycle
What are the light reactions of photosynthesis?
Involve the capture of light energy by pigment molecules and the utilization of that energy to synthesize NADPH and ATP
What is the Calvin cycle of photosynthesis?
Electrons and protons carried by NADPH and he energy of ATP hydrolysis are used to convert CO2 into a carbohydrate
In eukaryotes, where does photosynthesis take place?
The chloroplast
Where does the light reactions of photosynthesis take place in the chloroplast of eukaryotes? What about the Calvin cycle?
In between the outer membrane and inner membrane in a space which contains thylakoids
Calvin cycle is found in the stroma of the inner membrane
Why are phytoplankton for abundant in the poles oceans rather than the equator?
The poles are more nutrient rich and can support large phytoplankton communities
What is the photosynthetic apparatus?
A series of large protein complexes found in the thylakoid membrane that are responsible for the light reactions
What is a photon of light?
Contains a fixed amount of energy that is inversely related to its wavelength
Shorter he wavelength, the greater the amount of energy the photons of that wavelength contain
What are the three possible events that can occur after a pigment molecule absorbs a photon of light?
- Excited electrons from molecule return to ground state releasing heat or light known as fluorescence
- The energy of the excited electron is transferred to a neighbouring pigment molecule
- The exited electron is transferred from the pigment molecule to a nearby electron-accepting molecule
What is an absorption spectrum?
A plot of the absorption of light as a function of wavelength
What is the action spectrum?
A plot of the effectiveness of light of particular wavelengths in driving a process
What are photosystems?
Complexes within the thylakoid membrane that trap photons of light and use the energy to oxidize a reaction centre chlorophyll
What are the 3 stops in the electron transport of photosynthesis?
- Photosystem II absorbs photon of light then electrons flow using PQ to:
- Cytochrome complex sends electrons using copper-protein plasticyanin to:
- Photosystem I which donates electrons to iron sultry protein called ferredoxin which donates electrons to NADP+
What is photophosphorylation?
The process of using light to generate ATP
How many photons of light are required to generate one molecule of NADPH by linear electron transport?
2 photons
One absorbed by photosystem II
One absorbed by photosystem I
What are the three phases of the Calvin cycle?
- Fixation- incorporates carbon atom from CO2 into one molecule of five carbon sugar
- Reduction- gets addition phosphate from breakdown of ATP
- Regeneration- two molecules of G3P are produced per turn of the cycle, total of six carbon atoms
What is rubisco? What is it’s weakness?
Considered the most important enzyme of the biosphere because by catalyzing CO2 fixation in all photoautotrophs, it provides the source of organic carbon for most of the worlds organisms
It is insufficient at fixing CO2
What is photorespiration?
The wasteful process that uses ATP to consume O2 and release CO2
Which process gains carbon: carboxylation reaction or oxygenation reaction?
Carboxylation reaction
Why do high temperature increase photorespiration?
Because the solubility of CO2 decreases as the temperature goes up which makes the oxygenation reaction more common
What product is good at preventing photorespiration?
C4 metabolism
What are the similarities between photosynthesis and cellular respiration?
Both have key phosphorylation reactions involving an electron transport system
G3P is found in both
