Chapter 7- Phtosynthesis Flashcards
What are autotrophs?
Organisms capable of making their own food
What are photoautotrophs?
Organisms capable of making their own food, and food for heterotrophs (you and me), using the energy of sunlight to make organic molecules from water and carbon dioxide
Photosynthesis occurs in what 3 things?
Plants
Uni/multi-cellular algae
Some prokaryotes
Photosynthesis consists of how many stages?
2
What are the 2 stages of photosynthesis?
Light reactions (the photo part) Calvin cycle (synthesis part)
The light reactions occur where?
In the thylakoids
Light reactions do what?
Split water
Release O2
Produce ATP
Form NADPH
How does CO2/O2 enters/exits plant cells?
Through tiny pores called Stomata
The chloroplast is formed by ______ membranes, enclosing an inner compartment filled with ______.
Two
Stroma, a thick fluid
What is suspended in the Stroma of the chloroplast?
Thylakoids
Thylakoids, concentrated in stacks, are called what?
Grana (singular: granum)
The thylakoids membranes contain what?
The chlorophyll molecules that capture light energy
During photosynthesis, in the summary equation, which molecules are split first two obtain sugar?
Who hypothesized this?
When was it confirmed?
Summary equation:
(6CO2 + 6H20 = C6H12O6 + 602)
Breaks the bonds of water, not carbon dioxide, to produce the 6O2 from photosynthesis.
1930s- C.B. van Niel
Confirmed 20 years later
Photosynthesis and _____ are _____ reactions.
Redox reactions
What becomes reduced and oxidized in the photosynthesis summary equation?
CO2 become reduced
H2O becomes oxidized
The Calvin cycle occurs where?
In the Stroma of the chloroplast
The Calvin cycle forms _____ from _____, using _____ and _____.
Sugar
CO2
ATP (product of light cycle)
NADPH (product of light cycle)
Light reactions occur where?
In the thylakoids
What is the process of light reactions?
- Water is split, 02 is released outside the chloroplast
- H+ electrons are transferred to the electron carrier NADP+, reducing it to NADPH
- Generate ATP FROM ADP + P
Light reactions produce _____ and the Calvin cycle produces _____.
O2
Sugar
What is the first step of the Calvin cycle?
Carbon fixation
What is carbon fixation?
Incorporating carbon from CO2 into organic compounds
Once carbon fixation is complete, what occurs in the Calvin cycle?
The carbon compounds are reduced to sugars
The electrons required in the Calvin cycle to reduce carbon compounds comes from where?
The NADPH produced from the light cycle
Chemical energy (ATP) for the Calvin cycle comes from where?
ATP produced in the light cycle
What drives light reactions?
Visible radiation absorbed by pigments
Sunlight contains energy called what?
Electromagnetic energy, or radiation
What is the electromagnetic spectrum?
The full range of electromagnetic wavelengths from very short (gamma) to very long, radio waves
In the electromagnetic spectrum, as the wavelength get shorter, what occurs to the amount of energy?
The energy increases
What is the wavelength?
Distance between crest of two waves
The shorter the wavelength, the _____.
Higher the energy
What are photons?
Discreet packets of energy
Discreet packets of energy are called _____.
Photons
Photons have _____ of light energy.
Fixed quantities
Pigments built into the thylakoids membrane absorb ______ and _____ or _____ other wavelengths.
Some wavelengths of light
Reflect
Transmit
When looking at a leaf, in regard to the electromagnetic spectrum, what are you seeing?
The green wavelengths that are not absorbed but transmitted and reflected by the pigments.
Chloroplasts contain ______ of pigment.
More than one type
Chlorophyll absorbs very little _____ and almost all _____.
Green light
Blue light
Carotenoids May do what?
Broaden the spectrum of light used for photosynthesis
Carotenoids have what kind of role?
Photo protection
What is photoprotection?
Carotenoids absorb and dissipate excess light energy that would otherwise damage chlorophyll or interact with O2 to form reactive oxidative molecules that can damage cell molecules
How many types of photosystems are in thylakoids?
2
What are the two photosystems in the thylakoids membrane?
Photosystem I
Photosystem II
Photosystem II is best at absorbing light at what wavelength?
680 nm (red)
Photosystem I is best at absorbing which wavelength?
700 nm
Photosystems I and II WORK TOGETHER TO PRODUCE ____.
ATP and NADPH
Light energy absorbed by the two Photosystems drives the flow of electrons from _____.
H2O to NADP+
The electron transport chain helps produce what?
The H+ concentration gradient across the thylakoids membrane, driving H+ through ATP synthase producing ATP
The chemiosmotic production of ATP is called?
Photophosphorylation
Chlorophyll molecules are organized into clusters called?
Photosystem
The Calvin Cycle uses what to produce what?
Uses ATP and NADPH to concert CO2 to sugar
The Calvin and Citric Acid cycles regenerate their starting material? T/F
True
Carbon enters the Calvin cycle, leaving as _____.
G3P (sugar, called glyceraldehyde-3-phosphate)
The Calvin cycle must be completed ____ times, fixing _____ molecules of _____.
3 Times
3 molecules
CO2
Who discovered the Calvin cycle? What year was he awarded Nobel Peace Prize?
Melvin Calvin
1961
What is carbon fixing?
Taking carbon from an inorganic molecule and making an organic molecule out of it
What are the steps of the Calvin cycle?
- Carbon fixation
- Reduction
- Release of one molecule of G3P
- Regeneration of the starting molecule, ribulose biphosphate (RuBP)
_____ is an emergent property of the _____ of a chloroplast, integrating the two stages of photosynthesis.
Photosynthesis
Structural organization
What are the reactants of the light cycle?
H2O, NADP+, ADP, P
What are the products of the light reaction?
O2, NADPH, ATP
Sugar made in chloroplasts supplies ______ and ______ to synthesize cell’s organic molecules.
Chemical energy
Carbon skeletons
Photorespiration reduces the efficiency of _____.
Photosynthesis
What is photorespiration?
In hot dry weather, C3 plants close their stomata to reduce water loss
- prevents CO2 from entering and O2 exiting
- as O2 builds up, rubisco adds O2 instead of CO2 to RuBP, cannot t be used in Calvin cycle
