biology ch10: photosynthesis
Outputs of Calvin Cycle
ADP, NADP, G3P
__ is produced during the light reactions. (3 things)
ATP, NADPH, molecular oxygen
what occurs during the calvin cycle?
CO2 is reduced, ATP is hydrolyzed and NADPH is oxidized
inputs of the calvin cycle
CO2, ATP, NADPH
The electrons derived from this oxidation reaction in the Calvin cycle are used to reduce ___ to ___.
CO2, G3P
What property of the pigment chlorophyll makes it appear green?
Chlorophyll absorbs all of the visible spectrum of light except green, which it reflects.
__ is produced in the reduction phase of the Calvin cycle.
G3P
In the light reactions, light energy is used to oxidize ___ to ___.
H20, O2
Which of the following is the correct order of electron flow in the light reactions of photosynthesis?
H2O → P680 chlorophyll a pair → PS II primary electron acceptor → Pq → cytochrome complex → Pc → P700 chlorophyll a pair → PS I primary electron acceptor → Fd → NADPH
The electrons derived from this oxidation reaction in the light reactions are used to reduce ___ to ___.
NADP+, NADPH
outputs of light reactions
NADPH, ATP, O2
The Calvin cycle oxidizes the light-reactions product ___ to ___.
NADPH, NADP+
If the Calvin cycle slows down, what will happen to the rate of O2 production in PS II, and why?
O2 production will slow down because less NADP+ will be regenerated in the Calvin cycle.
__ is regenerated in the third phase of the Calvin cycle, regeneration of the CO2 acceptor.
RuBP
ATP and NADPH produced in the light reactions provide the energy for the production of sugars in the Calvin cycle.
T
Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.
T
During the Calvin cycle, what happens during the carbon fixation phase?
The Calvin cycle incorporates each CO2 molecule, one at a time, by attaching it to a five-carbon sugar named ribulose bisphosphate.
When a pigment molecule in a light-harvesting complex absorbs a photon of light, what happens to its excited-state electron?
The electron falls back to its ground state, while passing its excited-state energy to an electron in a nearby pigment molecule.
Which of the following statements correctly describes the difference in carbon fixation between C3 and C4 plants?
The first product of carbon fixation in C4 plants is a four-carbon compound instead of a three-carbon compound.
During which process is molecular oxygen produced in photosynthesis?
The light reactions by linear electron flow
Suppose that the concentration of CO2 available for the Calvin cycle decreased by 50% (because the stomata closed to conserve water). Which statement correctly describes how O2 production would be affected? (Assume that the light intensity does not change.)
The rate of O2 production would decrease because the rate of ADP and NADP+ production by the Calvin cycle would decrease.
Why are most autotrophs referred to as the producers of the biosphere?
They are the ultimate sources of organic compounds for all nonautotrophic organisms.
The light reactions of photosynthesis use chemiosmosis to produce ATP that will be used in the Calvin cycle. The electrochemical gradient that drives this chemiosmosis is formed across which structure(s)?
Thylakoid membrane
Chlorophyll molecules are in which part of the chloroplast?
Thylakoid membranes
Metabolic pathways are typically redox processes. In photosynthesis, what molecule is oxidized and what molecule is reduced?
Water is oxidized and carbon dioxide is reduced.
You have a large, healthy philodendron that you carelessly leave in total darkness while you are away on vacation. You are surprised to find that it is still alive when you return. What has the plant been using for an energy source while in the dark?
While it did have access to light, the plant stored energy in the form of sugars or starch, and it was able to derive energy from the stored molecules during your vacation.
In C4 and CAM plants carbon dioxide is fixed in the _____ of mesophyll cells.
cytoplasm
During cellular respiration, ___ is oxidized and ___ is reduced.
glucose, oxygen
inputs of light reactions
light, water, ADP, NADP+
The energy used to produce ATP in the light reactions of photosynthesis comes from __________.
movement of H+ through a membrane
The process that is most like photophosphorylation is ___
oxidative phosphorylation in cellular respiration
In C3 plants the conservation of water promotes _____.
photorespiration
During the citric acid cycle, ___ is oxidized and ___ is reduced
pyruvate, NAD+
Where does the Calvin cycle of photosynthesis occur?
stroma
When chloroplast pigments absorb light, __________.
their electrons become excited
How does carbon dioxide enter the leaf?
through the stomata
C4 plants differ from C3 and CAM plants in that C4 plants _____.
transfer fixed carbon dioxide to cells in which the Calvin cycle occurs
Both mitochondria and chloroplasts __________.
use chemiosmosis to produce ATP
Where do the electrons entering photosystem II come from?
water
A photosystem consists of
- a reaction-center complex - light-harvesting complexes - chlorophyll molecules - primary electron acceptor
both PS II and PS I
- light absorption - reduction of primary electron acceptor
Photosystem II
- oxidation of water - reduction of ETC between 2 photosystems
Photosystem I
- reduction of NADP+ - oxidation of ETC between 2 photosystems
How many electrons at a time are passed between the pigment molecules in the light-harvesting complexes?
0
For every molecule of O2 that is released by photosystem II, ___ H2O molecules are needed, which together pass ___ electrons to the PS II reaction-center complex.
2, 4
