Chapter 8
Heterotroph
Must consume food to obtain organic molecules.
How is NADPH formed in PSI?
NADP+ reductase adds two electrons and a H+ to NADP+
What is the source of electrons used to reduce the C-O bond of 3-phosphoglycerate during the Calvin cycle?
NADPH
Which of the following are products of the light reactions of photosynthesis that are used as reactants in the Calvin cycle?
NADPH ATP
The steps of the light reactions of photosynthesis yield three major products:
NADPH ATP Oxygen
The products of the light reactions that are used by the Calvin cycle to make carbohydrates are ______________
NADPH and ATP
During the Calvin cycle, high-energy electrons are provided by ______, and the source of energy for the reactions is ______.
NADPH; ATP
What plant organelle is pictured here?
A chloroplast
The Calvin cycle uses energy from_________________ , and high-energy __________________ supplied by NADPH.
ATP electrons
True or false: Glucose is the primary output of the Calvin cycle.
False
True or false: In the reduction phase of the Calvin cycle, ATP is the source of electrons used to reduce a C-O bond to a C-H bond.
False
In the first phase of the ________, atmospheric carbon dioxide is fixed into a five carbon sugar.
Calvin cycle
What happens during photosynthesis?
Plants capture energy from sunlight and use it to synthesize organic molecules.
What is carbon fixation?
The incorporation of carbon into an organic molecule that is not a gas
Which of the following statements are true of carotenoids?
They may appear yellow, orange, or red. They are abundant in flowers and fruits. They are found in chloroplasts.
Photoautotrophs
Uses light energy to drive the synthesis of organic molecules from inorganic molecules.
A pigment is a molecule that can ______________
absorb light
A diagram that depicts the wavelengths of electromagnetic radiation that are absorbed by a pigment is termed a(n)
absorption spectrum
A graph that represents the wavelengths of light absorbed by a given pigment is called a(n)
absorption spectrum
A graph that shows the rate of photosynthesis plotted as a function of light wavelength is called a(n) _____________ spectrum for photosynthesis.
action
Organisms that can synthesize organic molecules from inorganic molecules are called _____________ , while those that must consume food to obtain organic molecules are termed _______________.
autotrophs heterotrophs
The end product of phase 2 of the Calvin cycle is G3P. This molecule is used to synthesize__________________ and to regenerate the starting material_________________ bisphosphate.
carbohydrates ribulose
In the light reactions, ATP is generated via ____________
chemiosmosis
The incorporation of carbon from CO2 in the atmosphere into an organic molecule is called carbon
fixation
The electrochemical gradient generated in the light reactions of photosynthesis is used primarily to __________________
generate ATP via ATP synthase
A product of the Calvin cycle is used to produce ________________ molecules that may be linked together to form a polysaccharide called starch.
glucose
O2 is produced in the thylakoid lumen via the ___________________
oxidation of water in photosystem II
The process by which plants capture light energy and use it to synthesize glucose and other organic molecules is called
photosynthesis
During photosynthesis, oxygen is produced by the
removal of electrons from water in PSII
The reactions of the Calvin cycle occur in the
stroma
The energy required for the synthesis of glucose from carbon dioxide ultimately comes from
sunlight
Where do light reactions occur?
thylakoid membrane
Which of the following are major chemical products of the light reactions of photosynthesis?
Oxygen ATP NADPH
What are the three phases of the Calvin cycle?
Regeneration of ribulose bisphosphate Reduction and carbohydrate production Carbon fixation
In the last phase of the Calvin cycle, what molecule is regenerated so that the next cycle can occur?
Ribulose bisphosphate
What enzyme is responsible for carbon fixation?
Rubisco
The oxidization of water by photosystem II causes the pH of the thylakoid lumen to ____________
decrease
As water is oxidized during photosynthesis, the pH of the thylakoid lumen __________________
decreases
Homologous genes have similarity to one another because they are ______________
derived from the same ancestral gene
In photosynthesis, light energy is converted to ___________ energy, which in turn is converted to _______________ energy in a sugar molecule.
electrochemical chemical
Light is a type of _______________ radiation because it consists of energy in the form of electric and magnetic fields.
electromagnetic
After a pair of _______________ reaches QB, each enters a transport chain in the thylakoid membrane.
electrons
NADP+ reductase generates NADPH by transferring two____________ and one _______________ ion to NADP+.
electrons hydrogen
Sunlight enables the synthesis of glucose from carbon dioxide by providing the ______________ that is necessary for the process.
energy
Genes that are derived from the same ancestral gene, and thus are similar to each other, are termed ____________ genes
homologous
Along their journey from PSII to PSI, electrons release energy as they pass from one electron carrier to the next. This energy is used to pump _____________ ions into the thylakoid lumen.
hydrogen
Electrons in the pigment molecules of photosystems I and II are excited by
light
The flow of electrons from PSII to PSI involves a direct movement, thus electrons end up at a different destination from where they started. This is called ______________ electron flow.
noncyclic
During photosynthesis, NADPH is synthesized by ________________
photosystem I
During noncyclic electron flow, electrons flow from water to __________
photosystem II, then to photosystem I, and ultimately are transferred to NADP+
The energy released as electrons pass from an electron carrier to another in the electron transport chain between photosystem II and photosystem I is used to _____________
pump H+ establish an electrochemical gradient
In the Calvin cycle, CO2 is
reduced
In the Fall, aspen leaves change from a green color to a lovely yellow color. Seasonal color changes in a leaf happen because ______________
the quantity of chlorophyll in a leaf declines, unmasking the carotenoids
Chlorophylls a and b are found bound to integral membrane proteins in the ______________ membrane of the chloroplast.
thylakoid
The two independent, light capturing complexes of proteins and pigments called photosystems I and II, are located in the _____________ membrane of the chloroplast.
thylakoid
The electrons that exit PSII are replenished by electrons from oxidized ___________________ , which yields oxygen gas that can be used by plant cells or released to the environment.
water
What is the flow of electrons from PSII to PSI called?
Linear electron flow
A major purpose of the electrochemical gradient generated in the light reactions of photosynthesis is to synthesize ___________________
ATP
Where are photosystems I and II located?
In the thylakoid membrane
What molecule is produced by photosystem II?
Oxygen
A key role of PSI is to produce high-energy electrons that are used to make ____________ .
NADPH
Why is light considered a form of electromagnetic radiation?
Because it consists of both electric and magnetic energy.
What molecule is reduced in the Calvin cycle?
CO2
This figure depicts a cellular organelle called a(n)
chloroplast
What is the product of the carbon fixation reaction catalyzed by rubisco in the Calvin cycle?
3-phosphoglycerate
Sequence the phases of the Calvin cycle from first (on top) to last.
1. Carbon Fixation 2. Reduction and Carbohydrate production 3. Regeneration of ribulose bisphosphate
Arrange the following molecules according to the order of electron flow during photosynthesis. Begin at the top with the location where electrons are first excited in noncyclic electron flow.
1.P680 2.Cytochrome Complex 3.Plastocyanin 4.P700 5.NADP+
What is the function of chlorophyll during photosynthesis?
It absorbs light energy.
What happens to a pair of electrons after it reaches QB?
It enters an electron transport chain in the thylakoid membrane.
Which of the following happens to the molecule formed by the addition of carbon dioxide to ribulose bisphosphate?
It is immediately split into two more stable three-carbon molecules.
What energy conversion occurs during photosynthesis?
Light energy is converted to electrochemical energy, which is converted to chemical energy.
What is a visualization of the rate of photosynthesis plotted as a function of light wavelength?
An action spectrum
Which of the following summarizes the events of the first phase of the Calvin cycle?
Atmospheric carbon dioxide is fixed into a five carbon sugar.
In plants, which of the following is polymerized to form starch?
Glucose
What is produced at the end of the second phase of the Calvin cycle?
Glyceraldehyde 3-phosphate
Which of the following is the primary output of the Calvin cycle?
Glyceraldehyde-3-phosphate
How does an electron located in the pigment of the light-harvesting complexes become excited?
Light excites an electron in a pigment found in the light-harvesting complexes of the photosystems.
Autotroph
Produces organic molecules from inorganic molecules.
Which phase of the Calvin cycle will require both ATP and NADPH?
Reduction and carbohydrate production
Which of following best describes the location of chlorophyll a and b within the chloroplasts of green plants?
Thylakoid membrane
Which of the following is the purpose of phase 3 of the Calvin cycle?
To create a new 5-carbon sugar for the "next" Calvin cycle
The G3P produced at the end of the second phase of the Calvin cycle is directly used for which of the following?
To make glucose or other carbohydrates To regenerate ribulose bisphosphate
Carbon dioxide is incorporated into a molecule of ribulose biphosphate to form an unstable 6-carbon intermediate that immediately splits into two 3-carbon molecules. This process is called
carbon fixation
The pigment molecules that cause autumn leaves to appear yellow and orange are called
carotenoids
Similar to ATP synthesis in mitochondria, ATP synthesis in chloroplasts is achieved by a(n)__________________ mechanism called photophosphorylation.
chemiosmotic
Green plants absorb light energy in photosynthesis using ____________ a and b.
chlorophyll
Plants appear green because they contain
chlorophyll
The green color of plants is due primarily to the absorptive properties of the pigment ____________ found in the chloroplasts.
chlorophyll
In comparison to a leaf that appears yellow, a leaf that appears green has more of the pigment _______________ . A leaf may appear more yellow due to the presence of pigments called ________________ .
chlorophyll carotenoid