ch 10 mastering biology
Which of the following statements correctly describes a distinction between autotrophs and heterotrophs?
Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic
What is the basic role of CO2 in photosynthesis?
CO2 is fixed or incorporated into organic molecules.
Select the most accurate statement describing the basic function of the light reactions of photosynthesis
The basic function of the light reactions of photosynthesis is the conversion of solar energy to chemical energy
What is the biological significance of the light-independent reactions of photosynthesis?
they convert carbon dioxide to sugar
Which of the following molecules are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
ATP and NADPH
Chloroplast membrane vesicles are equilibrated in a simple solution of pH 5 . The solution is then adjusted to pH 8 . Which of the following conclusions can be drawn from these experimental conditions?
ATP will not be produced because there is no ADP and inorganic phosphate in the solution
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.
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
Which molecule is the final electron acceptor for electrons from photosystem I?
NADP+
Part complete Which of the following products of the light reactions of photosynthesis is consumed during the Calvin cycle?
NADPH
The reducing power for Calvin cycle reactions is provided by which of the following molecules?
NADPH
Which of the following molecules is the primary product of photosystem I?
NADPH
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.
Under what conditions do photosynthesis and cellular respiration occur in most plants?
Photosynthesis occurs only in the light, and cellular respiration occurs in both the dark and the light.
Why are plants classified as producers?
Plants are classified as producers because they fix inorganic carbon into organic molecules
Which molecule is regenerated in the regeneration phase of the Calvin cycle? Without regeneration of this molecule, the Calvin cycle would stop.
RuBP
Select the correct statement about the Calvin cycle
The Calvin cycle has three phases: carbon fixation, reduction, and regeneration of RuBP.
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 best describes the relationship between the light-dependent and light-independent reactions of photosynthesis?
The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions.
What is the importance of the light-independent reactions in terms of carbon flow in the biosphere?
The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars
Plants are photoautotrophs. What does this mean?
They use light energy to drive the synthesis of organic molecules from inorganic materials.
The photosynthetic membranes are found in the _____ in plant cells
chloroplasts
In C4 and CAM plants carbon dioxide is fixed in the _____ of mesophyll cells.
cytoplasm
CAM plants keep stomata closed in the daytime, thus reducing loss of water. They can do this because they _____.
fix CO2 into organic acids during the night
In autotrophic bacteria, where is chlorophyll located?
in infolded regions of the plasma membrane
What happens to the free energy released as electrons are passed from photosystem II to photosystem I through a series of electron carriers?
it is used to establish and maintain a proton gradient
Which set of reactions uses H2O and produces O2?
light dependent reactions
Photosynthesis is a redox reaction. This means that H2O is _____ during the light reactions and CO2 is _____ during the Calvin cycle.
oxidized, reduced
Which of the following is a product of the light reactions of photosynthesis?
oxygen, ATP, and NADPH
Which term describes ATP production resulting from the capture of light energy by chlorophyll?
photophosphorylation
In C3 plants the conservation of water promotes _____.
photorespiration
Which process produces oxygen?
photosynthesis
According to the chemiosmotic hypothesis, what provides the energy that directly drives ATP synthesis?
proton gradient
Which of the following particles can pass through the ATP synthase channel?
protons
Which of the following processes occurs during the Calvin cycle?
regeneration of the CO2 acceptor
When light strikes chlorophyll molecules, they lose electrons, which are ultimately replaced by _____.
splitting water
The oxygen released by photosynthesis is produced by which of the following processes?
splitting water molecules
Where does the Calvin cycle occur?
stroma
The ultimate source of energy to support most life on Earth is _____.
sunlight
Why are C4 plants able to photosynthesize with no apparent photorespiration?
they use PEP carboxylase to initially fix CO2
Why are the reaction centers of photosystems composed of several structurally different pigments?
this arrangement enables the plant to absorb the light energy of a variety of wavelengths
C4 plants differ from C3 and CAM plants in that C4 plants _____.
transfer fixed carbon dioxide to cells in which the Calvin cycle occurs
The light reactions of photosynthesis use _____ and produce _____.
water, NADPH
How many electrons at a time are passed between the pigment molecules in the light-harvesting complexes?
0
Which of these equations best summarizes photosynthesis?
6 CO2 + 6 H2O → C6H12O6 + 6 O2
