Biology Exam 2 - Chapter 8: Photosynthesis

How is NADPH formed in PSI?

NADP+ reductase adds two electrons and a H+ to NADP+.

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

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

Which of the following are components of both PSI and PSII?

A reaction center A light-harvesting complex

A major purpose of the electrochemical gradient generated in the light reactions of photosynthesis is to synthesize__________

ATP

Which of the following are major chemical products of the light reactions of photosynthesis?

ATP NADPH Oxygen

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 Reason: NADPH is the source of electrons that will ultimately reduce a C-O bond.

True or false: Glucose is the primary output of the Calvin cycle.

False Reason: The primary output of the Calvin cycle is glyceraldehyde-3-phosphate, which can be used for glucose synthesis in another set of reactions.

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

In the first phase of the ______, atmospheric carbon dioxide is fixed into a five carbon sugar.

Calvin cycle

In plants, which of the following is polymerized to form starch?

Glucose

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

What part of a photosystem contains dozens of pigment molecules that absorb light photons?

The light-harvesting complex

Which of the following will remove a high energy electron from P680* and transfer it to a more stable molecule?

The reaction center

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.

Which of following best describes the location of chlorophyll a and b within the chloroplasts of green plants?

Thylakoid membrane

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

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

In the light reactions, ATP is generated via ____

chemiosmosis

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

Sunlight enables the synthesis of glucose from carbon dioxide by providing the_____________ that is necessary for the process.

energy, light energy, ATP, or ATPs

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 ______.

establish an electrochemical gradient pump H+

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

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 I

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, light, photons, sun, the sun, light energy, sun light, or solar energy

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/H2O

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

Homologous genes have similarity to one another because they are ______.

derived from the same ancestral gene

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

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

Genes that are derived from the same ancestral gene, and thus are similar to each other, are termed____________ genes.

homologous

PSI and PSII have two main components: a(n)________ -harvesting complex and a(n)________ center.

light and reaction

Electrons in the pigment molecules of photosystems I and II are excited by___________

light/photons/energy

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, linear, or non-cyclic

O2 is produced in the thylakoid lumen via the ______

oxidation of water in photosystem II

During photosynthesis, water is ______.

oxidized

During noncyclic electron flow, electrons flow from water to _____

photosystem II, then to photosystem I, and ultimately are transferred to NADP+

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 or chlorophyll

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

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

Where do the light reactions occur?

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

What is the source of electrons used to reduce the C-O bond of 3-phosphoglycerate during the Calvin cycle?

NADPH

The Calvin cycle uses energy from__________ , and high-energy__________ supplied by NADPH.

Blank 1: ATP, adenosine triphosphate, or adenosinetriphosphate Blank 2: electrons, e-, or electron

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.

Blank 1: H+, hydrogen, H, proton, or hydronium

The steps of the light reactions of photosynthesis yield three major products:_________ ,__________ , and_________ .

Blank 1: NADPH Blank 2: ATP or adenosine triphosphate Blank 3: oxygen, O2, 02, or o2

Organisms that can synthesize organic molecules from inorganic molecules are called___________ , while those that must consume food to obtain organic molecules are termed____________ .

Blank 1: autotrophs, photoautotrophs, autotrophic, autotroph, or photoautotroph Blank 2: heterotrophs, heterotrophic, or heterotroph

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__________ .

Blank 1: chlorophyll Blank 2: carotenoid

In photosynthesis, light energy is converted to___________ energy, which in turn is converted to___________ energy in a sugar molecule.

Blank 1: electrochemical Blank 2: chemical

NADP+ reductase generates NADPH by transferring two_________ and one_______ ion to NADP+.

Blank 1: electrons, e-, or electron Blank 2: H+, proton, hydrogen, or H

The light reactions of photosynthesis take place in the___________ membrane, while the Calvin cycle occurs in the___________ of the chloroplast.

Blank 1: thylakoid Blank 2: stroma

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

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+

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

Based on the Z scheme, how many photoactivation events occur during photosynthesis?

2

Match each type of organism with its correct description.

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.

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 is the role of the reaction center in a photosystem?

It transfers a high-energy electron to another molecule.

What energy conversion occurs during photosynthesis?

Light energy is converted to electrochemical energy, which is converted to chemical energy.

What happens when a photon of light is absorbed by a pigment molecule?

An electron is boosted to a higher level.

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.

What is produced at the end of the second phase 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.

Which of the following conditions affect the way the Calvin cycle operates in photosynthetic organisms?

Light intensity Water availability Temperature

Which phase of the Calvin cycle will require both ATP and NADPH?

Reduction and carbohydrate production

What are the three phases of the Calvin cycle?

Regeneration of ribulose bisphosphate Reduction and carbohydrate production Carbon fixation

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 regenerate ribulose bisphosphate To make glucose or other carbohydrates

Why is water required for the light reactions of photosynthesis?

To replace the electrons lost from P680

True or false: Water is oxidized during the light reactions of photosynthesis.

True

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 or carotenoid

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