GBIO 106 Chapter 5

Select all of the characteristics of C4 plants.

require less water than C3 plants, fewer and smaller stomata, and expend additional ATP to reduce photorespiration

Select all of the examples of C4 plants.

sugarcane, crabgrass, and corn

Before the first photosynthetic organisms evolved on Earth,

the atmosphere contained very little oxygen.

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

the sun

The light reactions produce ____________, and the carbon reactions produce ___________.

ATP and NADPH; glucose

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

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

thylakoids

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

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

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

CAM pathway and C4 pathway

Match the photosynthetic pigments with their correct descriptions. chlorophyll a chlorophyll b carotenoids

Chlorophyll a : most abundant pigment in plants; reflects green wavelengths of light Chlorophyll b: accessory pigment that reflects green wavelengths of light. Cartenoids: accessory pigment that reflect red, orange, and yellow wavelengths of light.

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

False

In algae and plants, photosystem _______ captures photon energy at wavelengths around 680 nm, and photosystem _____ captures photon energy at wavelengths around 700 nm.

II, I

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

The _______ reactions of photosynthesis use ATP and NADPH to reduce carbon dioxide to glucose molecules.

carbon

The ____________ reactions of photosynthesis use ATP and NADPH to reduce carbon dioxide to glucose 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

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

carbon fixation

ATP production using energy from a proton gradient across a membrane is called ______________ phosophorylation.

chemiosmotic

Photosynthesis and aerobic cellular respiration generate ATP through

chemiosmotic phosphorylation

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

Chlorophyll b and carotenoids are examples of

accessory pigments

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

antenna

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

grana

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

heterotrophs, released CO2 into the environment, and obtained glucose from their environment

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

higher O2 than CO2 concentration in leaves and closed stomata

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

increase.

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

kinetic

A long wavelength contains ____________ energy than a short wavelength.

less

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

mesophyll

ATP is a(n) ______________ that stores energy between phosphate groups and is synthesized during the ___________ reactions.

nucleotide; light

C3 plants are plants that

only use the C3 pathway to fix carbon.

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

photons

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 a metabolic pathway called __________, plants, algae, and some types of bacteria convert solar energy into chemical energy, such as glucose.

photosynthesis

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

photosystem

Select all the examples of CAM plants.

pineapple and cacti

Select all of the following that are photosynthetic organisms.

plants, algae, some microbes, and cyanobacteria

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

If there is a surpluse of glucose from photosynthesis, plants store the excess as __________, a complex carbohydrate.

starch

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

stroma

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

stroma

Select the names of the two stages of photosynthesis.

Carbon reactions and light reactions

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

glucose and other sugars

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

1%

The enzyme rubisco catalyzes the first step in the

Calvin cycle

Which of the following are typically or always heterotrophs?

Animals and Fungi

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

Autotrophs

What are other names for the carbon reactions of photosynthesis?

dark reactions and light-independent reactions

Place the following events in the correct order in which they occur in photosystem I, beginning with the first event at the top. Energy is passed to the electrons of the reaction center. Two excited electrons are passed the second electron transport chain. Antenna pigments capture a photon of light.

1. Antenna pigments capture a photon of light. 2. Energy is passed to the electrons of the reaction center. 3. Two excited electrons are passed the second 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. Light energy is transferred to the reaction center. Antenna pigments capture a photon of light. Two electrons carrying potential energy are passed to the electron transport chain.

1. Antenna pigments capture a photon of light. 2. Light energy is transferred to the reaction center. 3. Two electrons carrying potential energy are passed to the electron transport chain.

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

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. Carbon dioxide is stored as malate in vacuoles within mesophyll cells. Malate is moved from the vacuoles to the chloroplasts of mesophyll cells and the carbon dioxide is released. Carbon dioxide diffuses into leaves when stomata are open at night. The chloroplasts can then fix carbon dioxide in the Calvin cycle, even when the stomata are closed during the day.

1. Carbon dioxide diffuses into leaves when stomata are open at night. 2. Carbon dioxide is stored as malate in vacuoles within mesophyll cells. 3. Malate is moved from the vacuoles to the chloroplasts of mesophyll cells and the carbon dioxide is released. 4. The chloroplasts can then fix carbon dioxide in the Calvin cycle, even when the stomata are closed during the day.

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

1. The electron transport chain receives energized electrons from photosystem II. 2. The electrons are shuttled through a series of proteins in the thylakoid membrane. 3. The energy lost from the electrons drives the active transport of protons from the stroma into the thylakoid space. 4. The electrons arrive at photosystem I.

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

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.

What happens to the glucose produced in photosynthesis? Select all that apply.

Combined with other molecules to form larger compounds, used to build cellulose of cell walls, and used as energy for cellular respiration.

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

Light energy.

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

NADPH

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

NADPH

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

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

Select all the components of a photosystem.

accessory pigments, proteins, chlorophyll pigments, and a reaction center chlorophyll

How does life depend on photosynthesis? Select all that apply.

Provides food for hetertrophs that eat photosynthesizers, incorporates atmospheric CO2 into organic compunds, provides food for photosynthesizers, and produces oxygen essential to many forms of life.

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

Reaction center

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

Rubisco adds oxygen instead of carbon dioxide to RuBP.

Select all the examples of C3 plants.

Spinach, most trees, and peanuts.

What statement accurately describes how the two photosystems function in the light reactions?

They function sequentially, with photosystem II acting first.

As described in this chapter's Investigating Life essay, algae living in salamander eggs transfer some sugars to the developing embryo. How did the researchers determine how much sugar the embryo received from the algae?

They tagged CO2 with a radioactive isotope and then measured how much carbon moved to the embryo.

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

Math the component of the electromagnetic spectrum with the correct description: Ultraviolet radiation Visible light Infrared radiation

Ultraviolet Radiation: Photons are high-energy and can damage DNA> Visible Light: Photons provide energy for photosynthesis. Infrared Radiation: Photons contain little energy, which is mostly converted to heat.

The range of possible frequencies of radiation is called the

electromagnetic spectrum

A group of proteins in the thylakoid membrane that shuttles electrons between the proteins and other carriers is called a(n) ______________ ____________ chain.

electron transport

Match each chloroplast structure with its correct description: two membranes stroma thylakoids thylakoid space

two membranes: surround each chloroplast stroma: fluid matrix within the chloroplast thylakoids: stacked within the stroma and studded with pigment molecules thylakoid space: volume enclosed by thylakoid membranes

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.

water