Biology Exam 2 Chapter 8
Carbohydrates are very important to plant cells because they:
-form the building block for many organic macromolecules -can be used as an energy reserve
What provides the energy for the synthesis of ATP in the light reactions of photosynthesis?
A proton gradient across a membrane
In photosynthesis, carbon dioxide is reduced and H2A is oxidized. What type of chemical reaction is this?
A redox reaction
Why is light considered a form of electromagnetic radiation?
Because it consists of both electric and magnetic energy
Why is it significant that energy from excited electrons in photosynthesis is "captured"?
Because the energy is not released but instead used productively
Why is it significant that in photosynthesis, photoexcited electrons are passed from one molecule to another?
Because the energy of the electron is "captured" rather than lost to the environment
What type of organisms carry out cellular respiration?
Both heterotrophs and photoautotrophs
This is the general equation for photosynthesis in green plants: CO2+ 2H2O + light energy→ CH2O + O2 + H2O. What represents the balanced products of the reaction if we account for the production of glucose (C6H12O6) from 6 molecules of CO2?
C6H12O6 + 6O2 + 6H2O
According to the general equation for photosynthesis, CO2+ 2H2A + light energy →
CH2O, A2, H2O
In the first phase of the ______, atmospheric carbon dioxide is fixed into a five carbon sugar.
Calvin Cycle
What is the origin of the carbons in a carbohydrate generated by photosynthesis?
Carbon dioxide in the atmosphere
What is the purpose of the light reactions of photosynthesis?
Conversion of light energy to chemical energy
Which of the following organisms are photoautotrophs?
Cyanobacteria Algae Green plants
Which of the following is the primary output of the Calvin cycle?
Glyceraldehyde-3-phosphate
In this diagram of a chloroplast, the structure that is circled is a(n);
Granum (stack of green plates)
The energy that is released as electrons pass from one electron carrier to the next is used to pump ions into the thylakoid lumen.
H+
What is carbon fixation?
Incorporation of carbon into an organic molecule that is not a gas
What happens to a pair of electrons after it reaches QB?
It enters an electron transport chain in the thylakoid membrane
What three things may happen to light when it strikes an object?
It may change direction. It may pass through the object. It may be absorbed.
How does photosynthesis benefit organisms that are not plants? Select all that apply.
It produces organic molecules that other organisms use as food. It produces oxygen that can be used for cellular respiration.
What energy conversion occurs during photosynthesis?
Light energy is converted to electrochemical energy, which is converted to chemical energy
How does an electron present 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.
During noncyclic electron flow, high-energy electrons are ultimately transferred to:
NADP+
The synthesis of NADPH is catalyzed by which of the following?
NADP+ reductase
How is NADPH formed in PSI?
NADP+ reductase adds two electrons and a H+ to NADP+
A key role of PSI is to produce high-energy electrons that are used to make
NADPH
During photosynthesis, serves as an electron carrier that can accept two high-energy electrons.
NADPH
Which molecule is used as an electron carrier during photosynthesis?
NADPH
Which of the following are products of the light reactions of photosynthesis that are used as reactants in the Calvin cycle?
NADPH ATP
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
Why is water required for the light reactions of photosynthesis?
To replace the electrons lost from P680
Photoautotroph
Uses light energy to drive the synthesis of organic molecules from inorganic molecules
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
A pigment is a molecule that can:
absorb light
The role of the light-harvesting complex is to:
absorb photons of light
When light strikes an object, the light may pass through the object, have its direction changed by the object (reflected), or be by the object.
absorbed
A graph that represents the wavelengths of light absorbed by a given pigment is called a(n):
absorption spectrum
The diagram pictured shows an:
absorption spectrum for individual pigments
What happens when a photon of light is absorbed by a pigment molecule?
an electron is boosted to a higher level
The wavelength of visible light is
between 380-740 nm
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
Similar to a mitochondrion, a(n) contains an outer and inner membrane, with an intermembrane space between the two. Unlike a mitochondrion, it also contains chlorophyll-containing membranes called membranes.
chloroplasts, thylakoid
Light is a type of ______ radiation because it consists of energy in the form of electric and magnetic fields.
electromagnetic
After a pair of reach QB, each enters a transport chain in the thylakoid membrane.
electrons
When an electron absorbs energy, it becomes
excited
After absorbing energy, an electron is said to be in a(n):
excited state
True or false: Glucose is the primary output of the Calvin cycle.
false
True or false: The synthesis of glucose from carbon dioxide is an exergonic reaction.
false
Visible light is longer than ______ _______ and shorter than ________ _______.
gamma rays, radio waves
The electrochemical gradient generated in the light reactions of photosynthesis is used primarily to:
generate ATP via ATP synthase
During photosynthesis, CO2 is reduced to produce
glucose
Living organisms that are not plants depend on photosynthesis because photosynthesis produces: (1) organic molecules such as that can be used for nourishment; and (2) the gas that makes up a large portion of the Earth's atmosphere.
glucose, oxygen
Thylakoids (or thylakoid membranes) stack on top of each other to form a(n)
granum
genes are similar to each other because they are derived from the same ancestral gene.
homologous
What is the function of chlorophyll during photosynthesis?
it absorbs light energy
What is the source of energy for photoautotrophs?
light
excite(s) electrons in pigment molecules in photosystems I and II.
light
Photosynthesis is divided into two stages: the reactions and the cycle.
light, Calvin
PSI and PSII have two main components: a(n) harvesting complex and a(n) center.
light, reaction
In PSII, water is "split" and the electrons are used to replenish excited electrons that are lost from the photosystem. The loss of electrons during the oxidation, or "splitting" of water, results in the formation of gas.
oxygen
In the following generalized equation for photosynthesis, what does "A" represent for photosynthesis in green plants? CO2+ 2H2A + light energy→ CH2O + A2 + H2O
oxygen
The splitting of water in photosystem II results in the production of gas.
oxygen
What molecule is produced by photosystem II?
oxygen
Which of the following are major chemical products of the light reactions of photosynthesis?
oxygen ATP NADPH
Because they use light energy to drive the synthesis of organic molecules, algae and cyanobacteria are considered:
photoautotrophs
What type of organisms produce most of the Earth's organic molecules?
photoautotrophs
The process by which plants capture light energy and use it to synthesize glucose and other organic molecules is called
photosynthesis
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
Electron transport generates an electrochemical H+ proton gradient across the thylakoid membrane. ATP is generated by the ATP synthase enzyme using the energy released when:
protons move down their electrochemical gradient by facilitated diffusion
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
Leaves appear green because they green light.
reflect
CO2 and H2O are produced during cellular and consumed during the process of
respiration, photosynthesis
The light reactions convert energy into energy stored in covalent bonds.
solar, chemical
The pores in the surface of a leaf that can participate in gas exchange are called
stomata
In plants and algae, the Calvin cycle occurs in the ______ of chloroplasts.
stroma
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
Wavelength refers to:
the distance between the peaks in a wave pattern
The splitting of water, the transfer of high energy electrons from PSII to PSI, and the generation of NADPH all contribute to
the generation of a H+ gradient
In a green plant, the majority of photosynthesis takes place in:
the leaves
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.
During photosynthesis, oxygen is produced by:
the removal of electrons from water in PS2
Homologous genes are similar to one another because:
they are derived from the same ancestral gene
Chlorophylls a and b are found bound to integral membrane proteins in the membrane of the chloroplast.
thylakoid
The light-harvesting complex is found in the membrane.
thylakoid
The membrane contains pigment molecules, including chlorophyll.
thylakoid
The membrane of the chloroplast contains two independent, light capturing complexes of proteins and pigments called photosystems I and II.
thylakoid
Photosystems I and II are located in:
thylakoid membrane
Where do the light reactions occur?
thylakoid membrane
A granum is a stack of
thylakoids
True or false: Photoautotrophs metabolize organic molecules via cellular respiration to supply their energy needs.
true
True or false: The electromagnetic spectrum encompasses all possible wavelengths,
true
True or false: Water is oxidized during the light reactions of photosynthesis.
true
During photosynthesis in green plants, what molecule is oxidized?
water
The oxidation of results in the formation of oxygen gas and the replenishment of electrons lost from PSII.
water
Photosynthesis is a redox reaction. Select all of the following that are true of photosynthesis.
water is oxidized CO2 reduced
The Calvin cycle is affected by certain environmental conditions, including light intensity, availability, and
water, temp
The distance between the peaks in a wave pattern is the
wavelength
The light reactions of photosynthesis require water to supply two that are transferred to P680+.
electrons
NADP+ reductase transfers two and one to NADP+ to generate NADPH.
electrons, H+
In photosynthesis, glucose is synthesized from CO2. This reaction is:
endergonic
Sunlight provides the that is necessary for the synthesis of glucose from carbon dioxide.
energy
The light reactions of photosynthesis take place in the membrane, while the Calvin cycle occurs in the of the chloroplast.
thylakoid, stroma
According to the Z scheme, how many photoactivation events occur during photosynthesis?
2
The general equation for photosynthesis in green plants is: CO2+ 2H2O + light energy ----> CH2O + O2 + H2O. Which of the following represents the reactants (types and amount of each) that are required for the production of glucose (C6H12O6)?
6CO2 + 12H2O + light energy
Which of the following are components of both PSI and PSII?
A light harvesting complex A reaction center
A major purpose of the electrochemical gradient generated in the light reactions of photosynthesis is to synthesize
ATP
The light reactions of photosynthesis produce three chemical products: , , and .
ATP, NADPH, O2
Which of the following organisms can carry out photosynthesis?
Algae Bacteria Plants
Which of the following are chloroplast membranes?
An outer membrane The thylakoid membrane An inner membrane
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.
Within a chloroplast, where is the stroma located?
Between the thylakoid membrane and the inner membrane
Cellular respiration regenerates the ______ that is used during photosynthesis.
CO2
What molecule is reduced during the process of photosynthesis?
CO2
What molecule is reduced in the Calvin cycle?
CO2
What is the general equation for photosynthesis?
CO2 + 2H2A + light energy → CH2O + A2 + H2O
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.
H2O
Which of the following are products of the light reactions?
NADPH, O2, ATP
What is the product of the oxidation of water during photosynthesis?
O2
Through the process of photosynthesis, photoautotrophs produce:
O2 Organic molecules
In the generalized equation for photosynthesis, the reactants are CO2 and H2A. What two elements can be "A" in H2A represent?
Oxygen Sulfur
During photosynthesis, NADPH is synthesized by:
Photosystem I
What happens during photosynthesis?
Plants capture energy from sunlight and use it to synthesize organic molecules.
Autotroph
Produces organic molecules from inorganic molecules
In the last phase of the Calvin cycle, what molecule is regenerated so that the next cycle can occur?
Ribulose bisphosphate
Which of the structures enable a plant leaf to participate in gas exchange?
Stomata
What part of the chloroplast is indicated by the large red arrow in this diagram?
Stroma (pointing to brown area)
Which of the following conditions affect the way the Calvin cycle operates in photosynthetic organisms?
Temperature Light intensity Water availability
What part of a photosystem contains dozens of pigment molecules that absorb light photons?
The light-harvesting complex
How is a H+ electrochemical gradient established and maintained in photosynthesis?
The movement of electrons from PSII to PSI The formation of NADPH The splitting of water
Which of the following accepts an electron from P680*?
The primary electron acceptor
What is depicted in the absorption spectrum shown in this diagram?
The relative absorption of light of varying wavelengths by different pigments
What is the name of the space enclosed by the thylakoids?
The thylakoid lumen
Where is the light-harvesting complex found?
The thylakoid membrane
Which of the following membranes contains pigments in a green plant?
The thylakoid membrane
Why are carbohydrates critical for plant cells?
They provide a source of energy and form the precursors for most organic macromolecules
Sequence the phases of the Calvin cycle from first (on top) to last:
carbon fixation reduction regeneration
In the light reactions, ATP is generated via:
chemiosmosis
Similar to ATP synthesis in mitochondria, ATP synthesis in chloroplasts is achieved by a(n) mechanism called photophosphorylation.
chemiosmotic
The green color of plants is due primarily to the absorptive properties of the pigment found in the chloroplasts.
chlorophyl
Green plants utilize a and b to absorb light energy in photosynthesis.
chlorophyll
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
In cyanobacteria, the Calvin cycle occurs in the of the cells.
cytoplasm
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
In photosynthesis, light energy is converted to energy, which in turn is converted to energy in a sugar molecule.
electrochemical, chemical
When a pigment molecule absorbs a photon of light, a(n) is boosted to a higher energy level.
electron
The incorporation of carbon from CO2 in the atmosphere into an organic molecule is called carbon
fixation
The flow of electrons from PSII to PSI is called electron flow because electrons the electrons move linearly from PSII to PSI.
linear
The space inside a thylakoid, which is enclosed by the thylakoid membrane, is known as the thylakoid
lumen
Within a leaf, the cells that contain chloroplasts are found in the tissue known as
mesophyll
During photosynthesis, water is:
oxidized
The G3P produced at the end of the second phase of the Calvin cycle is directly used for which of the following? Select all that apply.
regenerate ribulose bisphosphate make glucose or other carbohydrates
The source of carbon for the carbohydrates synthesized in the Calvin cycle is ______ from the atmosphere.
carbon dioxide
Where are chloroplasts found in a leaf?
mesophyll
