College Biology: Chapter 8 Smartbook - Photosynthesis

in C4 plants, the first product of carbon fixation is?

a four carbon molecule

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

a reaction center, a light harvesting complex

a pigment is a molecule that can?

absorb light

the role of the light-harvesting complex is to?

absorb photons of light

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

an electron is boosted at 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

a ______ can synthesize organic molecules from inorganic molecules, while an ______ must consume food to obtain organic molecules

autotroph, heterotroph

why is light considered a form of electromagnetic radiation?

because it consists of both electric and magnetic energy

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

calvin cycle

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, RuBP

what chemical reaction is catalyzed by the enzyme rubisco?

carbon fixation

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

chemismotic

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

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 photosynthesis, light energy is converted to _______ energy, which in turn is converted to ______ energy in a sugar molecule

electrochemical, chemical

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 ________ reach 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

during resonance energy transfer, what is transferred from one molecule to another?

energy

the photosynthetic light reactions are composed of a series of?

energy transfers

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

true or false: glucose is the primary output of the Calvin cycle

false

the electrochemical gradient generated in the light reactions of photosynthesis is used primarily to?

generate ATP via ATP synthase

after ______ molecules are made, they may be linked together in a polysaccharide called starch

glucose

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

glucose

which of the following is the primary output of the Calvin cycle?

glyceraldehyde-3-phosphate

_______ genes are similar to each other because they are derived from the same ancestral gene

homologous

what is carbon fixation?

incorporating CO2 into organic molecules that is not a gas

what is the function of chlorophyll during photosynthesis?

it absorbs light energy

several dozen pigment molecules anchored to transmembrane proteins make up the __________-harvesting complex of a photosystem

light

the ______ reactions of photosynthesis are composed of a series of energy changes

light

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

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

light intensity, temperature, water availability

PSI and PSII have two main components: a _____ harvesting complex and a _____ center

light, reaction

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

light-harvesting complex

the flow of electrons from PSII to PSI is considered to be?

linear electron flow

in hot dry conditions, rubisco can attach O2 to RuBP in a process called ______. which ultimately produces CO2.

photorespiration

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 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?

pigment

the light-harvesting complex is composed of several dozen ____________ molecules that are anchored to transmembrane proteins

pigments

what happens during photosynthesis?

plants capture energy from sunlight and use it to synthesize organic molecules

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

what are the three phases of the Calvin cycle?

reduction and carbohydrate production, carbon fixation, regeneration of ribulose biphosphate

the G3P produced at the end of the second phase of the Calvin cycle is directly used for which of the following?

regenerate ribulose bisphosphate, make glucose or other carbohydrates

the energy of an excited electron can be transferred from one pigment molecule to another via ______ energy transfer

resonanace

in the last phase of the Calvin cycle, what molecule is regenerated so that the next cycle can occur?

ribulose biphosphate

what enzyme is responsible for carbon fixation?

rubisco

what happens during photorespiration?

rubisco attaches O2 to RuBP, and CO2 is produced.

the energy required for the synthesis of glucose from carbon dioxide ultimately comes from _____

sunlight

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

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

the reaction center

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

what are true of carotenoids?

they may appear yellow, orange, or red, they are abundant in flowers and fruits, they are found in chloroplasts

photosystems I and II are located in?

thylakoid membrane

where do light reactions occur?

thylakoid membrane

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

thylakoid membrane

the light reactions of photosynthesis take place in the _______ membrane, while the calvin cycle occurs in the ______ of the chloroplast.

thylakoid, stroma

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

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

the Calvin cycle is affected by certain environmental conditions, including light intensity,______ availability, and ______

water, temperature

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 biphosphate

a major purpose of the electrochemical gradient generated in the light reactions of photosynthesis is to synthesize ________

ATP

what molecule is reduced in the Calvin cycle?

CO2

which of the following are products of the light reactions that are used by the Calvin cycle to make carbohydrates?

NADHP and ATP

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

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

NADPH

the products of the light reactions of photosynthesis are _____, _______, and ______

NADPH, ATP, oxygen

green plants utilize ______ a and b to absorb light energy in photosynthesis

chlorophyll

NADP+ reductase transfers two ______ and one ______ to NADP+ to generate NADPH

electrons, H+

sunlight provides the that is necessary for the synthesis of glucose from carbon dioxide.

energy

in the process of carbon _______ carbon dioxide is incorporated into a molecule of ribulose biphosphate forming an unstable 6 carbon intermediate that immediately splits into two 3-carbon molecules

fixation

the incorporation of carbon from CO2 in the atmosphere into an organic molecule is called carbon ______

fixation

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 molecule is produced by photosystem II?

oxygen

the reactions of the calvin cycle occur in the?

stroma

the ______ membrane of the chloroplast contains two independent, light capturing complexes of proteins and pigments called photosystems I and II

thylakoid

arrange the following molecules according to the order of electron flow during photosynthesis, beginning 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+

in some plants, carbon fixation yields a four-carbon molecule instead of 3GP as the first product. such plants are known as plants

C4

______ plants avoid water loss by closing their stomata during the day and opening them at night

CAM

how do CAM plants avoid water loss?

CAM plants close their stomata during the day and open them at night

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+