Unit 3 - Photosynthesis 1, 2 & 3 Flashcards
In what processes, do we lose energy to heat?
-digestion & absorption
-cellilar respiration
-cellular work
-biosynthesis
How do we replenish all the energy we lose as heat?
photosynthesis
How does photosynthesis counteract losing energy as heat?
it reestablishes and replenishes the lowest energy level / base of sunlight
process: creates Glucose (chemical energy) using CO2 and the energy from the sun (solar energy)
photosynthesis
process: converts glucose (chemical energy) to ATP (chemical energy)
respiration
equation for photosynthesis
CO2 + H2O + light –> O2 + glucose
equation for cellular respiration
O2 + glucose –> CO2 + H2O + ATP
Why is cellular respiration such an important process?
all living things use cellular respiration (including plants) to break down sugar and use the associated energy to grow, develop, and live (ex: maintain homeostasis)
Is the energy coming into photosynthesis and out of respiration the same?
no
What is energy possessed by an object because of its relative position or charge called?
potential energy
Energy that is higher up off the surface of Earth has _____ potential energy than objects lower to the ground.
more
Diffusion causes things to flow from _____ to ____ concentration (ex of potential energy).
high; low
How is electromagnetic energy (charge) a form of potential energy?
if there is a buildup of charge on one side, those atoms will rearrange themselves to equalize concentrations
_____ energy stored in a gradient can be converted to _______ energy when a gate is opened.
potential; kinetic
What affects the energy content of electrons?
relative position of electrons to the nuclei
Potential energy of an atom = distance of an _____ from its nucleus
electron
Which type of electrons are more stable:
-electrons closer to the nucleus
-electrons further from nucleus
closer to nucleus
Why are electrons that are closer to the nucleus more stable?
electron is at a lower energy state/orbital
Stable = _____ potential energy
low
Why are electrons that are further away from the nucleus less stable?
electron is at a higher energy state/orbital (excited state)
Excited = ______ potential energy
high
What is a way for electrons to jump energy levels?
absorption of a photon
What is the main importance of electrons being able to jump energy levels in an atom? WHY EVERYTHING ON EARTH EXISTS
once an electron encounters a photon it will jump to a higher energy level & then plants will find a way to harness this higher potential energy state
What is the main reason everything on earth exists?
ability of light to transfer energy into atoms by exciting electrons
What are the main steps to go from CO2 to the building blocks of life?
CO2–> Glucose–> Cellulose–> plants–> cows–> humans
How do we go from CO2 to the building blocks of life?
photosynthesis
How energy moves through systems is equivalent to how _____ moves through systems.
Carbon
______________:
-carbon and hydrogen (organic C)
-Cellulose, Glucose (C6H12O6)
-sugars usually end in -ose
carbohydrates (sugars)
The organic form of Carbon must contain which two atoms?
C & H
What are two important things to know about Carbon?
C needs 4 bonds & it almost never has a charge
Overall, what is the potential energy level of a C–O bond like?
low potential energy
Why does a covalent C–O bond have such low potential energy?
O is very electronegative and therefore holds electrons close to its nucleus (closer to nucleus = more stable = lower PE)
Overall, what is the potential energy level of a C–C bond like?
medium potential energy
Why does a covalent C–C bond have medium potential energy?
electrons are equidistant from both nuclei so C atoms have no partial charges and medium potential energy
Overall, what is the potential energy level of a C–H bond like?
high potential energy
Why does a covalent C–H bond have high potential energy?
H is electropositive and doesn’t hold onto its electrons very well so electrons are furthest from the nucleus (further from nucleus = unstable = high PE)
Rank the potential energy of the following from highest –> lowest:
C–H, C–O, C–C
C–H > C–C > C–O
What does OIL RIG stand for?
-oxidation is losing (energy)
-reduction is gaining (energy)
If you replace a C–H bond with a C–O bond, then C is being _____.
oxidized
What are 3 ways to oxidize a C?
-losing hydrogen
-losing electrons
-adding Oxygen
What are 3 ways to reduce a C?
-adding Hydrogen
-adding electrons
-losing Oxygen
Does a reduced or oxidized atom have more potential energy?
reduced
More _____ - more potential energy / has more Hydrogens / adds electrons / loses Oxygen.
reduced
More _____ - has less potential energy / has fewer Hydrogens / loses electrons / adds Oxygen.
oxidized
In redox paired reactions is compound A is oxidized by ____ electrons then compound B is _____ by _____ electrons.
losing; reduced; gaining
If compound A is originally a reduced compound but undergoes a rxn with compound B where it loses its electrons to compound B, then compound B would be called the ______ agent.
oxidizing (stealing energy)
If compound B is originally a oxidized compound but undergoes a rxn with compound A where it gains its electrons from compound A, then compound A would be called the ______ agent.
reducing (donating energy)
Oxidizing agent _____ energy and reducing agent _____ energy.
steals; donates
In the photosynthesis equation, is the C in CO2 being oxidized or reduced when converted to glucose C6H12O6?
reduced
How is C in CO2 reduced when converted into C6H12O6?
CO2 molecules only has low energy C-O bonds but Glucose has many C-H & higher energy bonds
Does photosynthesis take place more often on the upper or underside of a leaf?
upper surface
Why does photosynthesis take place on the UPPER side of a leaf?
palisade cells (mesophyll) are clustered along the upper surface
What are cell walls made of?
cellulose
What fills up the empty space in palisade cells to help with photosynthesis?
water
What is unique about the vacuole in a plant cell?
there is one, large central vacuole taking up 90% of cell volume
Unique characteristics of a plant cell?
-has a cell wall
-have chloroplasts that make their own food
-very large vacuole compared to animal cells
In what cell structure does photosynthesis take place in plant cells?
chloroplasts
What is the major difference between a prokaryote and eukaryote?
prokaryote: no membrane-bound nucleus or organelles
Shortly describe the origin stories of chloroplasts:
-chloroplasts used to be free-living cyanobacteria (blue/green algae)
-until a host cell swallowed and surrounded this cyanobacteria and trapped it in a vacuole
What is the mutualistic relationship between the host cell and cyanobacteria in endosymbiosis?
host cell: get sugar
cyanobacteria: is provided with protection and everything it needs to survive
Chloroplast is ______ DNA.
circular
What is unique about chloroplasts’ membrane?
it is double-layered
How do chloroplasts reproduce?
via binary fission and they divide independently of the parent cell
What do small ribosomes in a chloroplasts do?
make proteins
Photosynthetic bacteria converged with an ancestral ________ cell to produce photosynthetic protists such as algae.
eukaryotic
A geranium in a chloroplast is a stack of ______.
thylakoids
What is the space inside a thylakoid called?
lumen
Where do the light dependent reactions of photosynthesis occur?
thylakoids
Where do the light independent reactions of photosynthesis occur?
stroma
What are light absorbing pigments organized into in the thylakoid membrane?
photosystems
The lumen is separated from the stroma of a chloroplasts by what structure?
thylakoid membrane
Where are photosystems located in the chloroplasts?
on the thylakoid membrane
Where are light absorbing pigments, such as chlorophyll, located in the chloroplast?
in the photosystems
______: molecules that absorb visible wavelengths of light
pigments
What is the most abundant pigment on the planet?
chlorophyll
Why does chlorophyll appear green?
because it absorbs purple, blue & red, orange colors; therefore, it reflects the green/yellow wavelengths
What color of light does chlorophyll not absorb?
green
The C’s in glucose are more ______ than the C’s in CO2.
reduced
With chlorophyll and water, which is oxidized and which is reduced?
water: oxidized
chlorophyll: reduced
The light reactions create a gradient of H+ ions where there is a high concentration in the ______ of the chloroplast and a low concentration in the _______.
lumen; stroma
What are the reactants of photosynthesis?
CO2, light, water
What are the products of photosynthesis?
glucose and O2
____ reactions:
-convert light energy into chemical energy
-take place in thylakoid
light
______ reactions:
-convert CO2 and chemical energy into sugar
-take place in stroma
Calvin cycle (light independent reactions)
What are the 2 parts of photosynthesis?
(1) light reactions
(2) Calvin cycle
NADP+ is _____ at the end of photosystem I.
reduced
What are the reactants of the light reactions taking place in the lumen?
-water
-light
-NADP+
-ADP
What are the products of light reactions taking place in the lumen?
-O2
-NADPH
-ATP
What are the reactants of the Calvin cycle taking place in the stroma?
-ATP
-NADPH
-CO2
What are the products of the Calvin cycle taking place in the stroma?
-glucose
-NADP+
-ADP
Light reactions span the ______ membrane (transmembrane proteins).
thylakoid
What are the 4 major components of light reactions?
(1) Photosystem II
(2) ETC
(3) Photosystem I
(4) ATP Synthase
What happens in photosystem II?
-light is focused onto central chlorophyll
-photons excite its outer electron
-this increases the potential energy of the chlorophyll
-electron gets removed by the ETC and now chlorophyll is missing an electron and has a positive charge
After photosystem II, chlorophyll is looking to replace the electron it lost to the ETC and where does it find this?
water
What happens to water when chlorophyll takes its electron?
H20 splits into 1/2O2, 2H+, and 2e-
Where does the O2 go after H2O splits? The H+?
O2–> escapes into atmosphere
H+–> sticks around in lumen
In the reaction between chlorophyll and water, which is reduced and which is oxidized?
chlorophyll: reduced (oxidizing agent)
water: oxidized (reducing agent)
_______: when a molecule loses an H or an electrons or subs a high energy bond for something with less potential energy
oxidation
______: when a molecule gains an electron, or an H or replaces a low energy bond with one with more potential energy
reduction
Losing or gaining an H usually comes with an _____ as well.
electron
Chlorophyll+ is reduced by _____ into a form of chlorophyll that is ready for light.
reduced
For the light-dependent component of photosynthesis, what are the reactants?
H2O & light
After chlorophyll is reduced by water, its ready for what?
the next photon to excite it again
What happens to the electron in the ETC?
gradually loses energy as it moves through ETC
What is the energy lost by the electron in the ETC used for? What does this ultimately create?
used to pump H+ protons from the stroma into the lumen, creating an H+ GRADIENT
What is the main function of the ETC?
to move H+ ions from the stroma into the lumen
Where does chlorophyll+ get its electron from in Photosystem I?
ETC
What happens in photosystem I?
-light re-exites the electron
-electron is given to NADP reductase where NADP+ will form NADPH
NADP reductase converts _____ to _______.
NADP+; NADPH
What is NADP+ reduced to in photosystem I?
NADPH
What does the last part of the light reactions involve?
ATP generation through ATP Synthase enzyme, which uses the H+ gradient we just established to make ATP
What is the lost energy from the electron traveling through the ETC used for?
to pump Hydrogen ions from stroma into the interior of thylakoid – lumen
In PS I, when electron gets excited, its removed from chlorophyll and added to _____ which will find a loose ____ and form NADPH.
NADP+; H+
When hit by light, electron moves from ____ state to ______ state.
ground; excited
What converts NADP+ to NADPH?
NADP reductase
_____ transport does NOT require energy.
passive
____ transport: molecules can only move WITH their concentration gradient (high to low).
passive
_____ transport requires energy.
active
____ transport: moves molecules AGAINST their concentration gradient (low to high)
active
What kind of transport happens in the ETC with the movement of H+ ions from the stroma into the lumen?
active transport
Throughout previous steps H+ ions have been building up inside the thylakoid membrane (lumen), what 2 places do these come from?
(1) ETC
(2) splitting of H2O
What enzyme (protein) spans the thylakoid membrane & is a transmembrane protein?
ATP synthase
What flows through ATP synthase?
H+ ions
ATP synthase is like a channel that connects the ______ to the ______.
lumen; stroma
Is ATP needed for ATP synthase?
no; passive transport doesn’t require energy
What type of transport does ATP synthase undergo?
passive transport - flow from high to low [H+] concentration
ATP synthase takes _____ energy and converts it into _____ energy.
kinetic; chemical
ATP synthase converts ______ to ____ for use in the Calvin cycle.
ADP (low energy); ATP (high energy)
What happens to adenosine diphosphate (ADP) as a phosphate group is added?
it is turned into adenosine triphosphate (ATP); ADP is reduced/gains energy
What happens to ADP as it is converted to ATP?
reduction (gains energy)
What products of the light reactions are sent to the Calvin cycle?
ATP / NADPH
What products of the Calvin cycle are sent to the Light reactions?
NADP+ / ADP
Calvin cycle (light independent runs) use ______ energy to convert _____ into sugar.
chemical; CO2
What reduces CO2 to Glucose?
energy from ATP and NADPH (short term storage of chemical energy)
Does glucose store chemical for short or long-term?
long term
What are the 3 parts of the Calvin cycle?
(1) Fixation
(2) Reduction
(3) Regeneration
What enzyme fixes CO2 into organic C?
RuBisCo
What happens in the fixation step of Calvin cycle?
inorganic CO2 is fixated into organic C using RuBisCo enzyme
What happens in the reduction step of CC?
more reduction (adding energy) to 3C molecules
What happens in regeneration step of CC?
expulsion of 1/2 of glucose and return to original form 5C
Fixation starts with ___C (RuBP) and is combined with ___C from a CO2 molecule.
5; 1
What brings the 5C RuBP together with 1 CO2 molecule in the CC?
Rubisco
What is the result of 5C RuBP combining with 1C CO2?
6C broken up into 2, 3C sugars called PGA
Reduction starts with 2, 3C PGAs and reduces them into what?
2, 3C G3Ps
As we add energy to the 2, 3C PGAs (sugars), what is being oxidized?
ATP & NADPH
As we add energy to the 2, 3C PGAs (sugars), what is being reduced?
ADP and NADP+
Every 3 turns, how much of a glucose is produced and exits the CC cycle?
1 G3P = 1/2 a glucose
What are leftover G3Ps that didn’t go into glucose formation used for?
regeneration of RuBP
How many turns of the CC is needed to make 1 glucose molecule?
6
in making 1 glucose:
how many CO2 are needed?
6
in making 1 glucose:
how many RuBP 5C sugars are needed?
6
in making 1 glucose:
how many PGAs are needed?
12
in making 1 glucose:
how many ATP are needed?
18
in making 1 glucose:
how many ADP are needed?
18
in making 1 glucose:
how many NADPH are needed?
12
in making 1 glucose:
how many NADP+ are needed?
12
What two things power the conversion of one 3C sugar to another (PGA–> G3P)?
ATP & NADPH
What is the main thing used to make glucose?
G3P
3CO2 combined with 3RuBP acceptors can make ____ molecules of G3P?
6
In 3 turns, how many G3P molecules exit the cycle and go toward making 1/2 glucose?
1
In 3 turns, how many G3P molecules are recycled and regenerate 3 RuBP acceptor molecules?
5
How many ATP are converted to ADP during the reduction step of the CC? regeneration step?
reduction step: 12
regeneration step: 6
How many NADPH are converted to NADP+ in the reduction step?
12
____ ________ reactions convert light energy and H2O into chemical energy
light dependent
_____ _______ reactions convert CO2 and chemical energy into sugar
light independent
ATP synthase transports H+ ions from where to where?
from lumen into the stroma
