Chapter 10 Photosynthesis Flashcards
Which of the following processes occurs during the second phase, the reduction phase, of the Calvin cycle?
G3P production
Why are most autotrophs referred to as the producers of the biosphere?
They are the ultimate sources of organic compounds for all nonautotrophic organisms.
In the light reactions of photosynthesis, ATP is produced by photophosphorylation. Which of the listed processes is most similar to photophosphorylation?
Oxidative phosphorylation in cellular respiration
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.
Where do the electrons entering photosystem II come from?
Water
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.
Chlorophyll molecules are in which part of the chloroplast?
Thylakoid membranes
During which process is molecular oxygen produced in photosynthesis?
The light reactions by linear electron flow
Carbon dioxide and oxygen enter and exit a leaf by diffusion. Which structure(s) on a leaf allow(s) this process to happen?
Stomata
Both mitochondria and chloroplasts __________.
use chemiosmosis to produce ATP
The energy used to produce ATP in the light reactions of photosynthesis comes from __________.
movement of H+ through a membrane
The reactions of the Calvin cycle are not directly dependent on light, but they usually do not occur at night. Why?
The Calvin cycle requires products only produced when the photosystems are illuminated.
The light reactions of photosynthesis supply the Calvin cycle with __________.
ATP and NADPH.
The light reactions of photosynthesis occur in the __________.
thylakoids
The most important role of pigments in photosynthesis is to __________.
capture light energy
What property of the pigment chlorophyll makes it appear green?
Chlorophyll absorbs all of the visible spectrum of light except green, which it reflects.
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.
A photosystem consists of which of the following structures?
All of the listed structures are parts of a photosystem (Reaction-Centre Complex, Chlorophyll molecules, Light harvesting complexes and Primary electron acceptor).
In photosynthesis, plants use carbon from __________ to make sugar and other organic molecules.
Carbon Dioxide.
When chloroplast pigments absorb light, __________.
their electrons become excited
How does carbon dioxide enter the leaf?
Through the stomata
The light reactions of photosynthesis generate high-energy electrons, which end up in __________. The light reactions also produce __________ and __________.
NADPH; ATP; oxygen
Of the following, which occurs during the Calvin cycle?
CO2 is reduced.
Which of the following statements is a correct distinction between autotrophs and heterotrophs?
Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.
Where does the Calvin cycle of photosynthesis occur?
Stroma
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.
The Calvin cycle could not occur without the light reactions. Which of the following statements describes why this is the case?
ATP and NADPH produced in the light reactions provide the energy for the production of sugars in the Calvin cycle.
The source of the oxygen produced by photosynthesis has been identified through experiments using radioactive tracers. The oxygen comes from __________.
water
G3P is used in which of the following processes?
All of the listed processes can use G3P.
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
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.
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
Why is it correct to say that the linear electron flow of the light reactions directly captures energy in NADPH but only indirectly captures energy in ATP?
Electrons are directly transferred to NADP+ to form NADPH, but electron flow is used to generate a proton gradient for ATP synthesis. Electrons are not directly transferred to ATP.
