Photosynthesis Assignment

photorespiration

Oxygen is used by the enzyme rubisco in an energetically wasteful reaction.

Select all of the following that are typically or always heterotrophs.

fungi animals

Openings in the epidermis of a plant leaf or stem permit the ______ required for photosynthesis.

gas exchange

What product of photosynthesis is used as a building block for the cellulose found in plant cell walls?

glucose

In the Calvin cycle, ATP and NADPH are used to convert carbon dioxide into

glucose and other sugars.

Select all of the conditions that favor the photorespiration reaction of rubisco in a C3 plant.

higher O2 than CO2 concentration in leaves closed stomata

If stomata close to conserve water, CO2 in the leaves decreases, and O2 increases, which causes the rate of photorespiration to

increase.

A long wavelength contains ______ energy than a short wavelength.

less

C3 plants are plants that

only use the C3 pathway to fix carbon.

In the CAM pathway, stomata are ______ at night to let CO2 in when water loss is less and are _______ during the day while maintaining a high concentration of carbon dioxide in the chloroplasts.

open;closed

Within a photosystem, pigment molecules funnel photon energy to a pair of special chlorophyll a molecules called the

reaction center.

Select all of the characteristics of C4 plants.

require less water than C3 plants adapted to hot, sunny habitats expend additional ATP to reduce photorespiration

The enzyme that combines CO2 and RuBP is known as

rubisco.

thylakoids

stacked within stroma and studded with pigment molecules

In the thylakoid membrane, an enzyme complex called ATP _____ uses energy from protons passing through it to synthesize ATP.

synthase

The Calvin cycle is also called

the C3 pathway.

Before the first photosynthetic organisms evolved on Earth,

the atmosphere contained very little oxygen.

The molecule NADPH formed at the end of the photosynthetic electron transport chain will carry energetic electrons to

the carbon reactions.

What provides the energy to drive photosynthesis, which is an endergonic reaction?

the sun

Select all of the following that are products of the Calvin cycle.

ADP glucose (from PGAL) NADP+

What molecule produced by the light reactions stores potential energy in the covalent bonds between its phosphate groups?

ATP

What is produced in the light reactions which provides energy and reducing power for the carbon reactions?

ATP and NADPH

In the light reactions, pigment molecules in photosystems capture photons of light, and energy from light becomes stored as potential energy in

ATP and NADPH.

The light reactions produce _____, and the carbon reactions produce _____.

ATP and NADPH; glucose

The purple structure indicated by the arrow in the diagram is an enzyme called ______, which adds a phosphate to ADP using energy from a proton gradient.

ATP synthase

The Calvin cycle cannot proceed without the molecules ____ and _____ , which are produced by the light reactions of photosynthesis.

ATP;NADPH

The light reactions occur in the

thylakoid membranes.

During the photosynthetic electron transport chain, protons are pumped into the ______ from the stroma and then pass back to the stroma through ______ channels, which are enzyme complexes that can use the energy released from the protons to generate ATP.

thylakoid space; ATP synthase

Match each pathway letter on the image to the type of plant it represents. ABC

C3 plant;C4 plant;CAM plant

About 95% of plant species are ______ plants, which typically have a ______ efficiency rate of photosynthesis.

C3; low

When CO2 levels in C3 plant leaves are high (stomata are open), the ______ pathway is favored; when CO2 levels in C3 plant leaves are low and O2 levels are high (stomata are closed), the ______ pathway is favored.

C3; photorespiration

This diagram of a leaf cross-section shows bundle-sheath cells surrounded by mesophyll cells. The bundle-sheath cells are not directly exposed to gas exchange through stomata. The diagram shows a leaf from a ____ plant.

C4

What two pathways minimize photorespiration rate by ensuring that rubisco always encounters high CO2 concentrations?

C4 pathway CAM pathway

In ______ plants, the Calvin cycle occurs in bundle-sheath cells that are isolated from the leaf's air spaces, ensuring that rubisco always encounters high ______ concentrations.

C4; CO2

In what carbon fixation pathway is CO2 incorporated into malate during the night, and then released in chloroplasts during the day to drive the Calvin cycle in mesophyll cells?

CAM pathway

Select all of the following that describe CAM plants.

CO2 is incorporated into malate in mesophyll cells. The Calvin cycle occurs during the day. High concentrations of CO2 are maintained in chloroplasts during the day to favor the Calvin cycle.

In the first step of the Calvin cycle, ______ becomes incorporated into an organic compound, which is a process called ______.

CO2; carbon fixation

In what stage of photosynthesis is carbon from CO2 used to make carbohydrate molecules?

Calvin cycle

The carbon reactions of photosynthesis are also known as the ______, which occur in the stroma of chloroplasts.

Calvin cycle

The enzyme rubisco catalyzes the first step in the

Calvin cycle.

CAM photosynthesis

Carbon dioxide is incorporated into a 4-carbon molecule at night, and the Calvin cycle takes place during the day in mesophyll cells.

C3 pathway

Carbon dioxide is used by the enzyme rubisco to produce PGA.

C4 photosynthesis

Carbon dioxide is used to produce oxaloacetate, and the Calvin cycle takes place in bundle-sheath cells.

True or false: About 90% of the solar energy that reaches Earth is used for photosynthesis.

False

True or false: Photosynthesis only occurs on land.

False

What structure is circled in the chloroplast in the picture?

Granum

What surround stomata in plant leaves and can collapse to close stomata and conserve water?

Guard cells

The oxygen by-product of photosynthesis is created by the splitting of ______ molecules to replace the electrons ejected from the reaction center of photosystem II.

H2O

______ are organisms that obtain carbon by consuming preexisting organic molecules.

Heterotrophs

In C4 plants, the Calvin cycle takes place within ______ sheath cells, which are not exposed directly to atmospheric oxygen and therefore rubisco binds more often to carbon dioxide, reducing photorespiration.

bundle

Because they do not directly require light, the ______ reactions can also be called the light-independent reactions.

carbon

Ribulose bisphosphate combines with CO2 in the initial ______ step of the Calvin cycle.

carbon fixation

Select the names of the two stages of photosynthesis.

carbon reactions light reactions

ATP production using energy from a proton gradient across a membrane is called ______ phosphorylation.

chemiosmotic

Each plant photosystem contains about 300 ______ molecules and 50 accessory pigments.

chlorophyll a

The green, photosynthetic pigment found in plants, algae, and cyanobacteria is called

chlorophyll a.

In plants and algae, photosynthesis takes place in organelles called ______ , which contain thylakoid membranes embedded with the pigment chlorophyll.

chloroplasts

Select all of the examples of C4 plants.

corn sugarcane crabgrass

Photosynthetic pigments other than chlorophyll a are called ______ pigments.

accessory

carotenoids

accessory pigment that reflect red, orange, and yellow wavelengths of light

Place the following events in the correct order in which they occur in the C4 pathway, beginning at the top with the fixation of carbon into a four-carbon molecule. Instructions

1. CO2 is combined with a three-carbon molecule, forming the four-carbon molecule oxaloacetate.2. Oxaloacetate is usually reduced to malate.3. Malate moves to bundle-sheath cells away from O2-rich air spaces.4. CO2 is liberated and then fixed again as it enters the Calvin cycle.

Place the following events in the correct order in which they occur in the CAM pathway. Instructions

1. Carbon dioxide diffuses into the leaf when stomata are open at night.2. Carbon dioxide is stored as a four-carbon molecule in vacuoles within mesophyll cells.3. The stored four-carbon molecule is moved from vacuoles to choroplasts of mesophyll cells and carbon dioxide is released.4. Carbon dioxide enters the Calvin cycle when the stomata are closed during the day.

Place the following events in the correct order in which they occur in the Calvin cycle, beginning at the top with the carbon fixation step. Instructions

1. The enzyme rubisco combines carbon dioxide with RuBP to form a 6-carbon unstable molecule.2. The 6-carbon molecule splits to form PGA.3. PGA is converted into PGAL.4. Some PGAL is converted into glucose and other sugars, and some PGAL is converted back to RuBP.

Place the following events in the correct order in which they occur in photosystem I, beginning with the first event at the top. Instructions

Antenna pigments capture a photon of light; Energy is passed to the electrons of the reaction center; two excited electrons are passed along the electron transport chain.

Place the following events in the correct order in which they occur in photosystem II, beginning at the top with the entry of photons into the photosystem. Instructions

Antenna pigments capture a photon of light; light energy is transferred to the reaction center; two electrons carrying potential energy are passed to the electron transport chain.

What type of organism has the ability to produce organic compounds from inorganic substances?

Autotroph

In the light-independent reactions of photosynthesis, the ______ is a series of reactions in which the first stable compound formed is a 3-carbon molecule (PGA).

C3 pathway

What structure of a plant is shown in the image and is the site of photosynthesis?

Chloroplast

In what organelles does photosynthesis take place in a eukaryotic cell?

Chloroplasts

Radiowaves

Long wavelength, low energy

Visible light

Medium-sized wavelengths, perceived by humans as distinct colors

At the end of the electron transport chain of the light reactions, electrons reduce NADP+ and form ______

NADPH

What is generated using the energy of electrons at the end of the electron transport chain in the light reactions of photosynthesis?

NADPH

What product of the light reactions carries pairs of electrons to be used in the carbon reactions?

NADPH

ultraviolet radiation

Photons are high-energy and can damage DNA.

infrared radiation

Photons contain little energy, which is mostly converted to heat.

visible light

Photons provide energy for photosynthesis.

What metabolic pathway produces oxygen and carbohydrates that are essential to much of life on Earth?

Photosynthesis

What occurs during photorespiration that stops the Calvin cycle from proceeding?

Rubisco adds oxygen instead of carbon dioxide to RuBP.

In C4 plants, CO2 is first fixed into a four-carbon molecule in ______ cells by an enzyme other than rubisco; then in the adjacent ______ cells, CO2 is liberated and can enter the Calvin cycle.

mesophyll; bundle-sheath

Select all the examples of C3 plants.

peanuts most trees spinach

What three-carbon carbohydrate leaves the Calvin cycle and is used to build glucose and sucrose?

phosphoglyceraldehyde (PGAL)

The enzyme rubisco adds oxygen instead of carbon dioxide to RuBP in a process called

photorespiration.

The C4 and CAM pathways minimize ______ rate by increasing _______ concentrations encountered by rubisco.

photorespiration; CO2

In photosystem I, electrons ejected from the reaction center are replaced with electrons passed down the electron transport chain from

photosystem II.

Select all the examples of CAM plants.

pineapple cacti

Within a photosystem, what pigments capture photon energy and funnel the energy to the reaction center chlorophyll?

antenna pigments

Organisms called _____ are able to use inorganic molecules to make organic compounds.

autotrophs

The range of possible frequencies of radiation is called the ______ spectrum.

electromagnetic

What does the image show?

electromagnetic spectrum

During the light reactions, energized ________ from a reaction center chlorophyll a molecule are eventually donated to form the molecule NADPH.

electrons

When pigments in photosystem II absorb light energy, ______ are boosted to a higher energy level and passed to the electron transport chain that links the two photosystems.

electrons

stroma

fluid matrix within the chloroplast

In the overall reaction of photosynthesis, carbon dioxide and water molecules are converted into oxygen gas and ______, which the plant uses for food.

glucose

In each chloroplast, there are between 10 and 100 ______, which are stacks of thylakoids.

grana

All electromagnetic radiation consists of photons, which are discrete packets of ______ energy.

kinetic

During the ______ reactions of photosynthesis, energy from the sun is captured by pigments and stored as potential energy in the molecules of ATP and NADPH.

light

In plants, molecules called pigments are able to capture ______ for photosynthesis.

light energy

The image shows the cells in a cross-section of a leaf. The circled photosynthetic plant cells, which fill most of the interior of a leaf, are called _____ cells.

mesophyll

Within a plant leaf, most photosynthesis occurs in cells called ______ cells, which are often interspersed with air spaces to maximize gas exchange.

mesophyll

chlorophyll a

most abundant pigment in plants; reflects green wavelengths of light

In chemiosmotic phosphorylation, the production of ATP is powered by the

movement of protons across a membrane.

ATP is a(n) ______ that stores energy between phosphate groups and is synthesized during the ______ reactions of photosynthesis.

nucleotide; light

About 2.4 billion years ago, the gas ______ began to accumulate in Earth's atmosphere due to photosynthesis conducted by ancient ______.

oxygen; cyanobacteria

Oxygen from photosynthesis combines with free oxygen atoms in the atmosphere to produce ______, which shields Earth from harmful UV radiation.

ozone

Light consists of_______ , which are discrete packets of kinetic energy.

photons

In a metabolic process called________ , plants, algae, and some types of bacteria convert solar energy into chemical energy, such as glucose.

photosynthesis

Plants, algae, and some microorganisms use energy from the sun to make glucose and other carbohydrate molecules in a process called

photosynthesis.

A grouping of photosynthetic pigments and associated proteins is called a ______, which is embedded in the thylakoid membrane of chloroplasts.

photosystem

Light energy that is captured in photosynthesis is converted to ______ energy stored in the chemical bonds of molecules.

potential

The guard cells surrounding each stoma close the stomata periodically to

prevent water loss.

A ______ gradient is created across the thylakoid membrane using energy from electrons as they pass along the electron transport chain between photosystem II and photosystem I.

proton

In a photosystem, antenna pigments capture photon energy and funnel it to the ______ center, which consists of a pair of chlorophyll amolecules that actually use the light energy in photosynthetic reactions.

reaction

Select all of the following that are true about the photosynthetic pigment chlorophyll a.

reflects green light absorbs blue and red light most abundant photosynthetic pigment

Select all of the following that are characteristics of Earth's first organisms.

released CO2 into the environment heterotrophs obtained organic compounds from their environment

Plants conduct gas exchange in photosynthesis by bringing in carbon dioxide and releasing oxygen through openings called _____

stomata

In the illustration of a leaf cross-section, the blue and red arrows indicate the flow of gases through openings in leaves called

stomata.

The carbon reactions of photosynthesis occur in the ______, which is the fluid interior of chloroplasts.

stroma

Where do the carbon reactions of photosynthesis take place?

stroma within a chloroplast

Within the chloroplast, the gelatinous fluid containing DNA, ribosomes, and enzymes is called the

stroma.

two membranes

surround each chloroplast

Inside a chloroplast, the ______ are pancake-shaped membranes studded with photosynthetic pigments.

thylakoids

What happens to the glucose produced in photosynthesis?

used to build cellulose of cell walls combined with other molecules to form larger compounds used as energy for cellular respiration

Select all of the ways that photosynthesis is critical to life on Earth.

uses atmospheric CO2 to make carbohydrates provides food for photosynthesizers produces oxygen essential to many forms of life provides food for heterotrophs that eat photosynthesizers

thylakoid space

volume enclosed by thylakoid membranes

What molecule donates two electrons to the reaction center chlorophyll a of photosystem II to replace the electrons that were passed to the electron transport chain?

water

Select all of the molecules that are reactants of photosynthesis.

water (H2O) carbon dioxide (CO2)

In photosynthesis, the reactant ______ is oxidized, and the reactant ______ is reduced.

water; carbon dioxide

What is the distance a photon moves during a complete vibration?

wavelength

Photosynthetic pigments absorb different ______ of visible light.

wavelengths

Rank the following components of the electromagnetic spectrum from greatest amount of energy at the top to least amount of energy at the bottom.

x-rays; ultraviolet radiation; visible light; infrared radiation; microwaves.

Select all of the following that are alternate names for the carbon reactions of photosynthesis.

Calvin cycle light-independent reactions dark reactions

What is the most abundant photosynthetic pigment in plant cells?

Chlorophyll a

Select all of the following that correctly describe how the accumulation of atmospheric oxygen from photosynthesis affected the evolution of Earth's organisms.

More advanced organisms evolved which required high levels of oxygen. Organisms were able to conduct aerobic cellular respiration to extract more energy from food.

Select all of the molecules that are products of photosynthesis.

Oxygen (O2) Glucose (C6H12O6)

Gamma rays

Short wavelength, high energy

What part of the chloroplast is the arrow pointing to in the picture?

Stroma

Place the following events in the correct order in which they occur during the electron transport chain between photosystem II and photosystem I. Start with the first event at the top. Instructions

The electron transport chain receives energized electrons from photosystem 11; The electrons are shuttled through a series of proteins in the thylakoid membrane; The energy lost from the electrons drives the active transport of protons from the stroma into the thylakoid space; The electrons arrive at photosystem 1.

What part of the chloroplast is the red arrow pointing to in the picture?

Thylakoid

Why do photosynthetic organisms contain accessory pigments in addition to chlorophyll a?

To absorb wavelengths of light that chlorophyll a cannot and extend the range of wavelengths captured

True or false: All life on Earth depends directly or indirectly upon photosynthesis, except a few communities such as deep-ocean hydrothermal vent communities.

True

In a plant photosystem, the accessory pigments are arranged in ______, and so energy can quickly pass among them and be funneled to the ______.

a cluster close together; reaction center

chlorophyll b

accessory pigment that reflects green wavelengths of light

Chlorophyll b and carotenoids are examples of

accessory pigments.

Select all of the following that are photosynthetic organisms.

algae some groups of bacteria plants

The ______ pigments of photosystems pass the captured photon energy to the reaction center.

antenna

What percentage of the sunlight reaching Earth is captured in photosynthesis?

1%

The ______ reactions of photosynthesis use ATP and NADPH to reduce carbon dioxide to sugar molecules.

carbon

In the carbon reactions of photosynthesis, carbon from ______ is used to produce sugar molecules using energy from ATP and electrons from NADPH.

carbon dioxide