Lecture 12: Photosynthesis Flashcards
What is the chemical reaction for photosynthesis?
6CO2 + 6H2O —- C6H12O6 + 6O2
Does respiration have a negative delta G or does photosynthesis?
-Respiration does, photosynthesis has a positive delta G that requires energy to be put in the reaction
Where does photosynthesis get its energy from?
Sunlight
Where does photosynthesis occur?
Chloroplasts
How many chloroplasts can be found in plant leaf?
40-50 chloroplasts per plant leaf
Why are plant leaves so thin?
To capture sunlight more easily
Where do the dark reactions occur?
The storm
The Calvin cycle does not require light directly but what does it require?
-ATP
- NADH
Both produced by light reactions
Where do the light reactions occur?
Thylakoid membrane
What are some similarities between aerobic respiration and photosynthesis?(3)
- Both have an ETC
- Both have ATP synthase
- Citric acid cycle and Calvin cycle are opposite of each other
What does the citric acid cycle do vs the Calvin cycle?
Citric Acid Cycle: Oxidizes sugar and produces CO2
Calvin Cycle: Uses CO2 to build sugars
What are some differences between aerobic respiration and photosynthesis?(2)
- Photosynthesis uses light energy to split water into oxygen, protons and electrons used to initiate the ETC
- Photosynthesis uses NADPH
What’s the difference between NAD and NADP?
NADP has a phosphate group attached to it
Why is NADPH used in photosynthesis?
-NADH is used for catabolic reactions
-NADPH is used for anabolic reactions(helps support plant growth as it can be used to drive reactions producing fatty acids, and other polymers)
Are NADH and NADPH both found in plants and animals?
Yes
Why is the NADPH concentration kept high?
Used for reductions to make sugars
Why is the NAD concentration kept high?
NAD is used to oxidize sugar
Are short wavelengths high energy or low energy?
HIGH energy
Are long wavelengths high energy or low energy?
LOW energy
What wavelengths does photosynthesis absorb? what are these wavelengths called?
-400nm -700nm
-This is the visible light spectrum
What does visible light do to electrons?
Lifts them from the ground state to the excited state
Why are microwaves not used?(low energy)
Only induce vibrational energy
Why are gamma rays not used? (high energy)
Cause damage by ionization
What happens when an excited electron is brought back down to the ground state?
-Excited electrons contain potential energy
-This energy is released when brought back down to the ground state
What do the pigments chlorophyll and B carotene have that allows their electrons to be excited?
Both chlorophyll and B carotene have alternating bonds that have delocalized electrons that can be easily excited by certain visible wavelengths
Why are leaves green ?
Chlorophyll found in plants absorb blue and red light and reflects green light
What is the action spectrum?
A spectrum that shows at what wavelengths plants best absorb light and produce oxygen (oxygen is a waste product of photosynthesis, so this how’s how much photosynthesis is being done)
What does the solar spectrum show?
-Describes the type of electromagnetic radiation that arrives on earth
-Shows most sunlight arrives in the visible spectrum
Why did humans evolve on earth and not another planet?
-On other planets the sun radiates gamma rays or infrared rays which could not sustain human life
Why do leaves change from green to red in the fall?
Before the leaves drop to the ground, trees try to recoup their investments and try to shuttle chlorophyll and other chemicals back into their trunk and that leaves carotenoids in the leaves which leaves the leaves as red/orange
What can happen to an excited electron(not in photosynthesis)?
Excited electrons decay and fall back to ground state resulting in the emission of light (wavelength is lower as some is lost as heat)