Dans Lectures Flashcards
What animals produces the most o2 through photosynthesis?
Cytoplankton
How many semi interdependent reactions are there involved in photosynthesis?
80+
What wavelengths have more energy associated with them?
Short Wavelengths
What is the role of photoreceptive pigments
Capture radiant energy from the sun
What is the primary photoreceptive pigment?
Chlorophyll a
What color are carotenoids?
Orange
What color are phycobilins?
Blue-violet - Red
What color are anthophyks?
Yellow - Brown
Where does photosynthesis occur?
Chloroplasts
Where is chlorophyll produced?
Chloroplasts
What are photosystems?
Clusters of light trapping pigments in thylakoid membranes
Where is light energy absorbed?
LHC
What is O2 produced from in photosynthesis?
H2O
When is CO2 needed in the photosynthesis reaction process?
Light Independent reactions to produce glycogen
What is the phlogiston theory?
Only living (phlogiston) material can be burned
What did Joseph Priestly find out?
That the air is an inert pure substance
Who discovered O2?
Antonie Lavoisier
Where does synthesis occur?
Stroma
What do chloroplasts require to work?
electron acceptors
Where does chlorophyll get its spare electron from?
H2O
What two chemicals supply the energy for enzymes to work?
ATP and NADPH
What type of system involves a light-dependent reaction?
Photosystem
What is the first stage of a photosystem scheme?
II (Splits water an releases o2, H+ and ATP), then I (Produces NADPH and H+)
What is photolysis?
The diffusion of oxygen into the atmosphere
What is H+ only way out of a plant cell?
ATP synthase
What are the features of a light dependent reaction?
Uses light energy
Add water
Electron receptor
CO2 not necessary
What are the features of a light-independent reaction?
Uses ATP, NADPH
Uses CO2
Produces Carbohydrates
Light not necessary
What is the role of fluorescence?
The absorbance of light energy at one wavelength and re-emitting it at a longer wavelength
When will a particle be released as fluorescence?
When it is too energetic
What type of light does chlorophyll a absorb?
Blue light
When does chlorophyll absorb a photon?
Photochemistry
Fluorescence
Heat
What is the photosynthetic yield?
It shows how stressed the leaf
What is the most widely used fluorescent parameter?
FV/FM
When is there less fluorescence in a leaf?
When the leaf is exposed to heat and stress
What is the calvin cycle?
Light-independent reaction -
Series of enzyme-driven reactions to produce a sugar
What percentage of chloroplast protein does rubisco constitute?
50%
Where does rubisco originate?
The stroma of a chloroplast
Where does starch and sucrose synthesis take place?
Starch: Chloroplast
Sucrose: Cytoplasm
What are the three phases of the Calvin Cycle?
Carboxylation, reduction, regeneration of RUBP
What is photoinhibition?
Reduces the rate of photosynthesis as the plant is exposed to high light.
Ie. plants produce 9680, which is a strong oxidant
What are xanthophylls and what are their roles?
They protect the plant through dissipating light energy as heat. This reduces photosynthesis but protects the plant.
Where does photosynthesis take place?
Mesophyll cells
What is photorespiration?
The plant uses O2 for biosynthesis. No carbon fixed. Loses carbon chain. Reduces oxygen uptake.
What is C4 photosynthesis?
Separates reaction chambers.
Energetically costly.
Produces Oxyleoate
Where are light dependent and independent reactions taking place in a C4 plant?
Light Dependent: Mesophyll cells
Light Independent: Bundle sheath
How do C4 plants pass oxygen between mesophyll cells and the bundle sheath cells. Describe this process
Uses PEP to fix carbon.
Produces CO2.
Carbon cycle continues as usual
What are some advantages of C4 plants
CO2 greater
Reduces H2O loss
More efficient use of Nitrogen from rubisco
What are the disadvantages of C4 plants?
Require 6 additional ATP to work
What is alarm photosynthesis?
Uses carbon oxylate crystals as carbon providers under drought stress
What is CAM?
Similar to C4. Separates cycles from night and day
What happens in the night and day in the CAM cycle?
Night: Malic acid produced. Stomata open
Day: Malic acid decarboxylated. CO2 fixed
Leading to the more efficient use of H2O
What type of photosynthesis mechanism in plants has a higher photosynthetic rate?
C3 plants have the higher photosynthetic rate
What type of photosynthesis mechanism in plants has a higher photosynthetic rate?
C3 plants have a higher photosynthetic rate
What is diffusion?
The net movement of water molecules from high concentration to low concentration
What happens when molecules reach equilibrium?
There’s no net movement of molecules
What is osmosis?
Diffusion of water molecules. Helps water cross a partially permeable membrane
What is water potential?
Potential for water molecules to move
What is the highest potential of water?
0
How does water move?
It moves along gradients of water potential
In what direction does water move in terms of water potential?
It moves towards the more negative water potential
When soil has high salinity what water potential does it have?
a very negative one
What is the water table?
Pure water just under the soil
