Unit 7 Flashcards
what are photosynthetic organisms in an ecosystem
producers
how are producers involved in evergy flow in an ecosystem
take in sunlight and convert it to chemical energy of sugars
how do producers recycle chemical nutrients in an ecosystem
convert CO2 and H2O to sugar and O2
why are plants autotrophs
bc they make their own food
what types of organisms besides plants are producers
algae, kelp, cyanobacteria, other prokaryotes
organisms that produce food using the energy of light
photoautotrophs
what part of the leaf contains chloroplasts
mesophyll layer
how many membranes do chloroplasts have
two
where is the chlorophyll located within chloroplast?
in thylakoid, within stacks of grana
reactants of photosyntehsis
water and carbon dioxide
products of photosynthesis
glucose, water, oxygen
where is the oxygen from - which reactant
water
photosynthesis equation
CO2 + H2O -> C6H12O6 + O2 + H2O
what is reduced in photosynthesis?
carbon dioxide to glucose
what is oxidized in photosynthesis?
water to oxygen
what kind of reaction is photosynthesis
redox (oxidation-reduction)
what is photosynthesis the opposite of
cellular respiration - it reverses the flow and involves an uphill climb that is endergonic - cell. resp. is food to energy, photosynthesis is energy to food
how do electrons gain energy
by being boosted up an energy hill
what provides the boost for electrons
light energy captured by chlorophyll molecules
where is the chemical energy made from light energy stored
in the chemical bonds of sugar molecules (glucose)
form of photosystem
contains light harvesting complex w pigments (chlorophyll)
function of photosystem
- acts as light gathering antenna
- pigments absorb photons, passing the energy, until it reaches the reaction center complex
- reaction center complex: electron transfer from chlorophyll to primary electron acceptor
fixed amount of light energy
photon
what happens when a pigment absorbs a photon
electron jumps to a level farther from nucleus ( excited state )
why do electrons return from their excited state?
it is unstable
what occurs as the electrons return to ground state
release of heat and light
how many photosystems are in lights reactions
2: Photosystem II and Photosystem I
reactants of light reactions
photons of light energy
products of light reactions
ATP, NADPH, O2
how are the photosystems related
the electrons boosted by PII are passed through the “ATP mill” and boosted again by PI, to reduce NADP+ to NADPH
where are light reactions occuring
thylakoid membrane
how does sunlight enter photosystem
through the chlorophyll molecules
what flows through the membrane
electrons
where the electrons end up after light reactions
NADPH
when H2O is split, whre do the protons begin to build up?
thylakoid space
what concentration are the protons going to in light reactions
low to high - get their energy from the electrons passing through
Define photoautotroph & provide examples
an organism that produces organic molecules from inorganic molecules using light. examples: kelp, alga, and cyanobacteria
What is the function of chlorophyll & where is it found in a plant cell?
a light absorbing pigment in the chloroplast that plays a central role in converting solar energy to chemical energy. the chlorophyll are found in the thylakoid
Where are most cloroplasts concentrated within plants?
concentrated in the cells of th mesophyll, a green tissue in the interior of a leaf
Write the equation for photosynthesis & label which reactant becomes reduced and which reactant becomes oxidized.
6CO2 + 6H2O–>C6h12o6 +6O2
CO2 is reduced to C6H12O6
6H2O is oxidized to 6O2
how is atp generated in light reactions
ATP synthase - protons diffuse and potential energy is released
what type of diffusion is it when protons go from high to low concentration through the atp synthase
facilitated diffusion
where do nadph and atp go
calvin cycle
where does calvin cycle take place
stroma
reactants of calvin cycle
atp, nadph, co2
products of calvin cycle
glucose (2 G3P), adp + p, nadp+
starting material for calvin cycle - always in it
ribulose biphosphate (RuBP)
what happens to rubp in calvin cycle
carbon is added through enzyme rubisco, then splits in half into 2 3-PGA (3C molecules)
does rubisco change
no - keeps its shape so it can repeat
phosphoglyceric acid
3-PGA
what does atp do to 3pga
it adds a phosphate group, which makes atp ADP
what does nadph do to 3pga
it removes a phosphate group and gives H to it, which reduces it
for every __ CO2 fixed, __ G3P are created
3, 6
_ of the _ G3P goes to make glucose, the other _ reyccle to RuBP
1 of the 6, 5 recycle
What are the 2 steps of photosynthesis & where do they occur
- Light Reactions-thylakoids
2. Calvin Cycle/Dark Reactions- stroma
Describe the form & function of a photosystem.
Form- Contains light-harvesting complex, with pigments (chlorophyll)
Function-Act as a light-gathering antenna
What are the reactants of the Calvin cycle & where did they come from?
CO2-environment(air)
NADH-Light Reactions
ATP-Light Reactions
For every 3 CO2 “fixed”, how many molcules of the energy-rich G3P are created & where do they go?
For every 3 CO2 “fixed”, 6 G3P are created: 1 G3P is used to make sugar (glucose)
5 G3P are rearranged to regenerate RuBP
what is a autotroph?
organism that produces their own food through photosynthesis
what are photo autotrophs?
Organisms that produce food using the energy of light
what is a producer?
photosynthetic organisms in an ecosystem
ex of autotrophs
plants
where does photosynthesis occur in a leaf?
chloroplast
what are the parts and functions of a chloroplast?
has stroma, grana, thylakoid
function: to make photosynthesis by converting light energy to sugars
reactants of photosynthesis?
co2 and h20
where do the reactants of photosynthesis come from?
the environment
what are the products of photosynthesis?
c6h12o6, h20, o2
what reactant is being reduced?
co2
what reactant is being oxidized?
h20
what molecule is split?
water
where do the parts of of the split water molecule go?
the hydrogen (and electrons) are lost
Is photosynthesis endergonic of exergonic?
endergonic
what are the 2 stages of photosynthesis?
light reactions, calvin cycle
what two molecules link the the stages of photosynthesis?
atp
nadph
what is a photon?
a fixed amount of energy
what happens when a photon is absorbed by a pigment?
electrons jump to a level further from the nucleus
what are the reactants of the light reactions?
h20, nadp+, adp+p, light
where to reactants in the light reactions come from?
nadp+ ADP+P=calvin cycle
h20, light = environment
where are photosystems located?
thylakoid membrane
what is the form of a photosystem?
l
Contains light-harvesting complex, with pigments (chlorophyll)
What is the function of a photosystem?
➢Act as a light-gathering antenna
➢Pigments absorb photons, passing the energy, until it reaches the reaction center complex
➢Reaction center complex: e- transfer from chlorophyll to primary e- acceptor
products of the light reactions?
o2, nadph, atp
where do the dark reactions occur?
stroma
reactants of dark reactions? come from?
nadph, atp
from the light reactions
what is RuBP?
five carbon sugar
how is rubisco involved in the dark reactions?
it is an enzyme that helps carbon fixation
How does RuBP change when CO2 enters the dark reactions?
it doesn’t
what happens to 3-PGA?
➢ATP phosphorylates 3-PGA, leaving ADP
How many G3P are created during the dark reactions? Where do they end up?
6 are created.
1 is used to make sugar
5 are rearranged to regenerate RuBP
what is photorespiration?
➢Rubisco adds oxygen instead of carbon dioxide to RuBP and produces a two-carbon compound, a process called photorespiration
why do some plants undergo photorespiration if no sugar is produced?
its an evolutionary relic
What do C4 plants do to prevent water loss in dry climates?
➢Some plants can close their stomata when the weather is hot and dry to conserve water but is able to make sugar by photosynthesis
➢These are called the C4 plants because they first fix carbon dioxide into a four-carbon compound
what is the problem with photorespiration?
➢Unlike photosynthesis, photorespiration produces no sugar, and unlike respiration, it produces no ATP
