Chapter 10 Photosynthesis Flashcards
What drives the endergonic reaction in photosynthesis?
Energy from light
The organelles in plants that carry out photosynthesis
Chloroplasts
What has the green pigment and absorbs light?
Chlorophyll
Describe the anatomy of chloroplast
Outer and inner membrane, inter membrane space, 3rd membrane (thylakoid) contains pigment molecules
A stack of thylakoids make up the _________
Granum
The tiny openings where gassed pass though in pants
Stomata
The liquid part inside the chloroplast
Stroma
What is the equation for photosynthesis?
6 CO2 + 12 H2O + Light Energy
Yields
C6H12O6 + 6 O2 + 6 H2O
Chloroplasts split water into hydrogen and oxygen, incorporating the electrons of ____________ into sugar molecules
O2 is released as a by product
Hydrogen
Photosynthesis is a redox reaction in which ________ is oxidized and ______________ is deduced
Water, CO2
Endergonic redox process, energy is used to reduce ___________
CO2
Photosynthesis consist of what two stages
Light reactions (photo part), Calvin cycle (the synthesis part) ***
Where does the photo part occur?
In thylakoid membrane of chloroplast
Steps of the light reactions
- split water
- releases oxygen
- reduces NADP+ to NADPH
- generate ATP from ADP by photophosphorylation
Where does the Calvin cycle take place?
Stroma
Steps in the Calvin cycle
- CO2 is incorporated into existing organic molecules (carbon fixation)
- reduced fixed carbon into carbohydrate (sugar)
- ATP -provides chemical energy - NADPH -provides reducing power
Thylakoids transform light energy into the chemical energy of _____ and ________
ATP, NADPH
Light is a type of _____________ radiation
Electromagnetic
Do shorter or longer wavelengths have more energy?
Shorter
What is the wavelength range for visible light?
380-750 nm
What light drive photosynthesis?
Visible light
Each pigment absorbs a specific ______________
Wavelength
Substances that absorb visible light
Pigments in the chloroplast
Wavelengths that are not absorbed are _________ or ________
Reflected or transmitted
When pigments absorb light, electrons….
Get boosted to higher energy levels
- measures a pigment’s ability to absorb various wavelengths
- sends light through pigments and measures the fraction of light transmitted at each wavelength
Spectrophotometer
What are the main pigments of photosynthesis?
Chlorophyll a -key pigment
Chlorophyll d, carotenoids (accessory)
What color range of of light works best for photosynthesis?
Violet-blue and red
Profiles the relative effectiveness of different wavelengths of radiation I’m driving a process
An action spectrum
After an electron absorbs energy; it goes from ground to…..
An unstable excited state
Excited electrons fall back to ground state release energy as what?
Heat or Florences
Two components of a photosystem?
Reaction center- pair of chlorophyll a molecules and the primary electron acceptor
Light- harvesting complexes- pigment molecules bound to proteins, funnel the energy of photons to the reaction center
What is the first step of the light reactions?
Solar-powered transfer of an electron from chlorophyll a molecule to the primary electron acceptor
Two types of photosystems in the thylakoid membrane
Photosystem II and I
Which PS functions first?
PS II
PS II is best at absorbing a wavelength of ______ nm
And the reaction center chlorophyll a is called_______
680, P680
PS I is best at absorbing a wavelength of ______ nm. The reaction-center chlorophyll a is called ______
700, P700
The two phot systems work together to use light energy to generate _____ and ______
ATP and NADPH
During the light reactions, there are two possible routes for electron flow:
- cyclic
- noncyclic (the primary pathway)
Cyclic electron flow uses PS I only (no NADPH or water)
Noncyclic electron flow produces ________ and ________
ATP and NADPH
SP I primary role?
To make NADPH
Addition of H+ to NADP contributes to H+ electrochemical gradient
Photosystems I and II work together to make _____ and ______
ATP, NADPH
Linear or noncyclic electron flow
PS II
Excited electrons travel to PS I
-water is oxidized, generates O2 and H+
- releases energy in electron transport chain
-energy used to make H+ electrochemical gradient
ATP synthesis driven by flow of H+ from thylakoid _______ into _______ via ATP synthase
Lumen, stroma
How is the H+ gradient generated?
H+ is increased by
- thylakoid lumen by splitting of water - by ETC pumping H+ into lumen
H+ is deceased from formation of NADPH In stroma
Electrons begin in PS II and eventually transfer to ________ linear processes produce ATP and NADPH in ________ amounts
NADPH, equal
The three products produced by light reactions
- O2 produced in thylakoid lumen by oxidation of H2O by PS II 2 electrons transferred to P680+
- NADPH produced In the stroma from high-energy electrons that start in PS II and boosted in PS I
- ATP produced in stroma by H+ electrochemical gradient
Cyclic electron flow only makes ______ and only uses PS __
ATP, 1
Cyclic electron flow generates surplus ______, satisfying the higher demand in the Calvin cycle
ATP
Cyclic photophosphorylation
- Electron cycling relaxes energy to transport H+ into lumen driving synthesis if ATP
- PS electrons excited, real see e wordy and eventually return to PS I
- favored when ATP Levels are low
- favored when NADP+ is low and NADPH is high
Water is split by _______ on the side of the membrane _______ the thylakoid space
PS II, facing
The diffusion of H+ form ________ back you the _______ powers ATP synthase
The thylakoid space, stroma
ATP and NADPH are produced on the side facing the ______, where the Calvin cycle takes place
Stroma
Light reactions generate ATP and increase the potential energy of electrons by moving them from ________ to ________
H2O, NADPH
- ATP and NADPH used to make carbohydrates
- CO2 incorporated into carbohydrates (precursor to all organic molecules, energy storage)
Calvin-Benson cycle
The Calvin cycle uses ______ and ________ to convert CO2 to sugar
ATP and NADH
Carbon enters the Calvin cycle as CO2 and leaves as a sugar named……
Glyceraldehyde-3-phosphate (G3P)
Glucose is not directly made
For every 6 CO2 incorporated in the Calvin cycle, ______ ATP and ______ NADPH used
18, 12
What are the three phases of the Calvin cycle?
- Carbon fixation
- reduction and carbohydrate production
- Regeneration of the CO2 acceptor RuBP
- first phase of the Calvin cycle
- CO2 is incorporated in RuBP using rubisco
- 6 carbons intermediates splits into 2 3PG
Carbon fixation
-second phase of the Calvin cycle
-ATP is used to concert 3PG into 1, 3-bisphosphoglycerate
-NADPH electrons reduce it to G3P
-6CO2 ——-> 12 G3P
(2 for carbohydrate, 20 for regeneration of RuBP
Reduction and carbohydrate production
- third phase of the Calvin cycle
- 10 G3P converted into 6 RuBP using 6 ATP
Regeneration of the CO2 acceptor RuBP
