Photosynthesis (pdbio exam 3) Flashcards
What is photosynthesis?
The plants way of converting sunlight to glucose and subsequently ATP via mitochondria and oxidative respiration.
What is an autotroph
organism that photosynthesizes
In plants, they use sunlight to convert ___ to ___.
H2O to O2
CO2 is then reduced to carbohydrates in a separate set of reactions. This process (reducing ___ and adding to an ____) is said to ___ CO2
CO2
organic molecule
“fix”
What is the equation for photosynthesis?
CO2 + H2O + light energy»_space; C6H1206 + O2 + H2O
What is reduced in the photosynthesis equation?
CO2 is reduced
What is oxidized in the photosynthesis equation?
H2O is oxidized
Where does photosynthesis occur?
In the chloroplast
What is the green pigment called that chloroplast contains?
chlorophyll
In the chloroplast there is no ____, therefore, all ATP stays in the chloroplasts and is used to synthesize ____
ATP transporter
sugar
What is a stack of thylakoid disks called?
the granum
What is the thick fluid found in between grand where the carbohydrate formation reactions occur in the chloroplast of plant cells undergoing photosynthesis?
the stroma
The _____ contains pigment molecules
thylakoid membrane
What is the inside pocket of a thylakoid disc called?
the thylakoid lumen
What are the two stages of photosynthesis?
Where do they take place?
What do they use and produce?
1) light reactions
- take place in thylakoid membranes
- use light energy and water and produce ATP, NADPH, and O2
2) dark reactions
- take place in the stroma
- use ATP, NADPH, and CO2 and produce glucose/carbohydrate
Where is the ETC located?
Along the membrane of the thylakoid
What is the electron source for photosynthesis?
Water
What is the difference between Photosystems I and II?
PSII: occurs first, electrons excited when light hits the pigments in the P680 photo center, breaks down (oxidizes) H2O to O2, releases energy in ETC and creates a H+ electrochemical gradient
PSI: occurs second, re-excites the electrons when light hits the pigments in the P700 photocenter, primary role is to make NADPH (meanwhile the H+ are leaving the thylakoid to the stroma through the ATP synthase creating ATP
Plants ____ colors that they don’t absorb well
reflect
The pigments don’t absorb ____ so the ____ color is reflected
green, green
What color wavelengths are great for photosynthesis?
Blue and red
What primarily protect chlorophyll by absorbing free radicals?
Carotenoids
The ____ scheme is a good representation of the energy levels at different points in the light reaction
Z
What are the three chemical products of the light reactions?
How/where produced?
- oxygen, O2: produced in the thylakoid lumen by oxidation of H2O by PSII
- NADPH: produced in the stroma from high-energy electrons that start in PSII and are boosted in PSI
- ATP: produced in stroma by ATP synthase using the H+ electrochemical gradient
What is another name for the Calvin cycle?
Carbon fixation
The carbon from ____ in the environment is used to synthesize carbohydrates
CO2
What is the main occurrence of the Calvin cycle?
CO2 is added to a 5 carbon and 6 carbon carbohydrates are formed
What enzyme facilitates the CO2 being added to a 5 carbon in the Calvin cycle?
rubisco
Variations in photosynthesis are due to what 3 factors?
Light intensity (incr = faster) Temperature (incr = faster) Water availability (good amount = faster)
The light reaction of photosynthesis takes place in the ____, while the Calvin cycle occurs in the ____ of the chloroplast.
thylakoid membrane
stroma
In photosynthesis, light energy is converted to ____ energy, which in turn is converted to ____ energy in a sugar molecule
electrochemical
chemical
T/F: The ATP used during the Calvin cycle in photosynthesis comes from cellular respiration.
False
