Chapter 8 Assignment
A key role of PSI is to produce high-energy electrons that are used to make
NADPH
A pigment is a molecule that can _____
absorb light
What is the function of chlorophyll during photosynthesis?
absorb light energy
The role of the light-harvesting complex is to ______.
absorb photons of light
What chemical reaction is catalyzed by the enzyme rubisco?
carbon fixation
Similar to ATP synthesis in mitochondria, ATP synthesis in chloroplasts is achieved by a(n _____mechanism called photophosphorylation
chemiosmotic
Similar to ATP synthesis in mitochondria, ATP synthesis in chloroplasts is achieved by a(n) _____ mechanism called photophosphorylation.
chemiosmotic
In the light reactions, ATP is generated via ______.
chemiosomosis
Green plants utilize ___a and b to absorb light energy in photosynthesis.
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 chloroplasts
chlorophyll
Light is a type of ______ radiation because it consists of energy in the form of electric and magnetic fields.
electromagnetic
When a pigment molecule absorbs a photon of light, a(n) ______is boosted to a higher energy level.
electron
NADP+ reductase transfers two ___ and one ____ion to NADP+ to generate NADPH.
electron and hydrogen
After a pair of _____reaches QB, each enters a transport chain in the thylakoid membrane
electrons
The light reactions of photosynthesis require water to supply two ____ that are transferred to P680+.
electrons
The light reactions of photosynthesis require water to supply two ____that are transferred to P680+.
electrons
Sunlight enables the synthesis of glucose from carbon dioxide by providing the ____that is necessary for the process.
energy
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 process of carbon ______, carbon dioxide is incorporated into a molecule of ribulose biphosphate forming an unstable 6 carbon intermediate that immediately splits into two 3-carbon molecules.
fixation
After ____molecules are made, they may be linked together in a polysaccharide called starch.
glucose
____ genes are similar to each other because they are derived from the same ancestral gene.
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
What part of a photosystem contains dozens of pigment molecules that absorb light photons?
light-harvesting complex
PSI and PSII have two main components: a(n) ____ -harvesting complex and a (n _____ center
light; reaction
The flow of electrons from PSII to PSI is considered to be:
linear electron flow
The flow of electrons from PSII to PSI is called ___electron flow because the electrons move linearly from PSII to PS1
linear non-cyclic
In hot dry conditions, rubisco can attach O2 to RuBP in a process called ______. which ultimately produces CO2.
photorespiration
The process by which plants capture light energy and use it to synthesize glucose and other organic molecules is called
photosynthesis
During photosynthesis, NADPH is synthesized by __
photosystem 1
A molecule that can absorb light energy is called a(n) ______.
pigment
The light-harvesting complex is composed of several dozen ______ molecules that are anchored to transmembrane proteins.
pigment
Which of the following will remove a high-energy electron from P680* and transfer it to a more stable molecule?
reaction center
In the Calvin cycle, CO2 is ______.
reduced
The energy of an excited electron can be transferred from one pigment molecule to another via ____ energy transfer
resonance
What enzyme is responsible for carbon fixation?
rubisco
The reactions of the Calvin cycle occur in the ______.
stroma
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 decline, unmasking the carotenoids
Chlorophylls a and b are found bound to integral membrane proteins in the _____ membrane of the chloroplast
thylakoid
The ___ membrane of the chloroplast contains two independent, light-capturing complexes of proteins and pigments called photosystems I and II.
thylakoid
Which of the following best describes the location of chlorophyll a and b within the chloroplasts of green plants?
thylakoid membrane
According to the Z scheme, how many photoactivation events occur during photosynthesis?
two
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
In C4 plants, the first product of carbon fixation is ______.
a four carbon molecule
What happens when a photon of light is absorbed by a pigment molecule?
an electron is boosted to a higher level
A major purpose of the electrochemical gradient generated in the light reactions of photosynthesis is to synthesize
ATP
The products of the light reactions of photosynthesis are
ATP Oxygen NADPH
Which of the following are major chemical products of the light reactions of photosynthesis?
ATP Oxygen NADPH
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.
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
Why is light considered a form of electromagnetic radiation?
Because it consists of both electric and magnetic energy.
In some plants, carbon fixation yields a four-carbon molecule instead of 3GP as the first product. Such plants are known as
C4
What molecule is reduced in the Calvin cycle?
CO2
In the first phase of the ______, atmospheric carbon dioxide is fixed into a five carbon sugar.
Calvin cycle
The pigment molecules that cause autumn leaves to appear yellow and orange are called
Carotenoids
A leaf that appears green has more of the pigment ______ than a leaf that appears yellow. A leaf may appear more yellow due to the presence of pigments called _____
Chlorophyll; carotenoid
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.
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 products of the light reactions that are used by the Calvin cycle to make carbohydrates are
NADPH and ATP
What happens during photosynthesis?
Plants capture energy from sunlight and use it to synthesize organic molecules.
In the last phase of the Calvin cycle, what molecule is regenerated so that the next cycle can occur?
Ribulose bisphosphate
What happens during photorespiration?
Rubisco attaches O2 to RuBP, and CO2 is produced.
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
Why is water required for the light reactions of photosynthesis?
To replace the electrons lost from P680
The Calvin cycle is affected by certain environmental conditions, including light intensity ______, and _____
Water availability Temperature
The model for photosynthesis that incorporates two photoactivation events and shows the series of energy changes during the light reactions of photosynthesis is called the ____ scheme
Z
Homologous genes have similarities 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
During resonance energy transfer, what is transferred from one molecule to another?
energy
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
Several dozen pigment molecules anchored to transmembrane proteins make up the ____ harvesting complex of a photosystem.
light
_____ excite(s) electrons in pigment molecules in photosystems I and II.
light
The splitting of water in photosystem II results in the production of ___ gas
oxygen
What molecule is produced by photosystem II?
oxygen
The energy required for the synthesis of glucose from carbon dioxide ultimately comes from
sunlight
During photosynthesis, oxygen is produced by:
the removal of electrons from water in PS2
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
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 -RuBP
Sequence the phases of the Calvin cycle from first (on top) to last.
-Carbon fixation -Reduction and carb production -Regeneration of ribulose bisphosphate
What are the three phases of the Calvin cycle?
-Carbon fixation -Reduction and carbohydrate production -Regeneration of ribulose bisphosphate
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
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+
Which of the following are components of both PSI and PSII?
A reaction center A light-harvesting complex
____plants avoid water loss by closing their stomata during the day and opening them at night.
CAM
How do CAM plants avoid water loss?
CAM plants close their stomata during the day and open them at night.
What energy conversion occurs during photosynthesis?
Light energy is converted to electrochemical energy, which is converted to chemical energy.
Which of the following conditions affect the way the Calvin cycle operates in photosynthetic organisms?
Temperature Light intensity Water availability
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.
In plants, which of the following is polymerized to form starch?
glucose
Where do the light reactions occur?
In the thylakoid membrane
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 is the role of the reaction center in a photosystem?
It transfers a high-energy electron to another molecule.
True or false: Glucose is the primary output of the Calvin cycle.
false
Which of the following is the primary output of the Calvin cycle?
Glyceraldehyde-3-phosphate
Match each type of organism with its correct description. heterotroph, autotroph, photoautotroph
Heterotroph: must consume food to obtain organic molecules Autotroph: Produces organic molecules from inorganic molecules. Photoautotroph: Uses light energy to drive the synthesis of organic molecules from inorganic molecules
Where are photosystems I and II located?
In the thylakoid membrane