Biology Exam 2 Chapter 8

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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


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