Chapter 8

In C3 plants, the first molecule observed following carbon dioxide fixation is a

3-carbon molecule

The resulting 6-carbon molecule splits into two molecules of 3-carbons, each called

3PG

What is the overall equation for photosynthesis?

6 CO2 + 6 H2O → C6H12O6 + 6 O2

cyclic electron pathway

Alternate form of the light-dependent reactions in photosynthesis that does not produce NADPH.

carotenoids

An accessory photosynthetic pigment of plants and algae that are often yellow or orange in color; consists of two classes—the xanthophylls and the carotenes.

RuBP carboxylase

An enzyme that starts the Calvin cycle reactions by catalyzing attachment of the carbon atom from CO2 to RuBP.

Enzymes in the fluid-filled stroma reduce ____

CO2

What causes leaves to appear green to us?

Chlorophylls a and b and the carotenoids largely absorb violet, indigo, blue, and red wavelengths and reflect green wavelengths.

ATP synthase

Complex of proteins in the cristae of mitochondria and thylakoid membrane of chloroplasts that produces ATP from the diffusion of hydrogen ions across a membrane.

3PG. ATP and NADPH from the light reactions are then used to reduce 3PG to

G3P

chlorophyll

Green photosynthetic pigment of algae and plants that absorbs solar energy; occurs as chlorophyll a and chlorophyll b.

Electrons from ___ replace those lost in photosystem II

H2O

noncyclic electron pathway

Light-dependent photosynthetic pathway that is used to generate ATP and NADPH; because the pathway is noncyclic, the electrons must be replaced by the splitting of water (photolysis).

The Calvin cycle reactions use ____ and ___ to reduce carbon dioxide.

NADP+ and ATP

The electrons energized in photosystem I pass to ____, which becomes ____

NADP+, NADPH

The oxidation of H2O releases

O2

autotrophs

Organism that can capture energy and synthesize organic molecules from inorganic nutrients.

heterotroph

Organism that cannot synthesize needed organic compounds from inorganic substances and therefore must take in organic food.

photosystem

Photosynthetic unit where solar energy is absorbed and high-energy electrons are generated; contains a pigment complex and an electron acceptor; occurs as PS (photosystem) I and PS II.

C3 plants

Plant Plant that fixes carbon dioxide via the Calvin cycle; the first stable product of C3 photosynthesis is a 3-carbon compound.

light reactions

Portion of photosynthesis that captures solar energy and takes place in thylakoid membranes of chloroplasts; it produces ATP and NADPH.

Calvin cycle reactions

Portion of photosynthesis that takes place in the stroma of chloroplasts and can occur in the dark; it uses the products of the light reactions to reduce CO2 to a carbohydrate.

photosynthesis

Process, usually occurring within chloroplasts, that uses solar energy to reduce carbon dioxide to carbohydrate.

The oxygen given off by photosynthesis comes from a. H2O. b. glucose. c. CO2. d. RuBP.

a

photosynthesis reduces CO2 to

a carbohydrate

Look at photosynthesis diagram

a. thylakoid b. oxygen c. stroma d. Calvin cycle e. granum

Both photosynthesis and cellular respiration utilize

an electron transport chain and ATP synthesis

In the cyclic electron pathway of the light reactions, electrons energized by the sun leave photosystem I and enter

an electron transport chain that produces a hydrogen ion gradient.

carbon dioxide fixation occurs ______, and the Calvin cycle occurs _______.

at night, during the day

Carbon dioxide fixation

attaches CO2 to a 5-carbon molecule named RuBP by the enzyme RuBP carboxylase

Why is photosynthesis essential for the continuance of life?

because by this process autotrophs manufacture the food needed for all life

the Calvin cycle occurs in ____ cells

bundle sheath

How are NADP+ and ATP produced?

by the light reactions in the thylakoid membranes of the grana after chlorophyll captures the energy of sunlight

CAM photosynthesis a. is the same as C4 photosynthesis. b. is an adaptation to cold environments in the Southern Hemisphere. c. is prevalent in desert plants that close their stomata during the day. d. occurs in plants that live in marshy areas. e. stands for "chloroplasts and mitochondria."

c

Cellular respiration and photosynthesis both a. use oxygen. b. produce carbon dioxide. c. contain an electron transport chain. d. occur in the chloroplast.

c

The function of light reactions is to a. obtain CO2. b. make carbohydrate. c. convert light energy into a usable form of chemical energy. d. regenerate RuBP.

c

Which of the following does not occur in photosynthesis? a. reduction of CO2 b. reduction of oxygen c. oxidation of water d. All of these are correct.

c

Cellular respiration oxidizes _______, and ______ is given off

carbohydrate CO2

During photosynthesis, solar energy is converted to

chemical energy within carbohydrates

In the absence of sunlight, plants are not able to engage in the Calvin cycle due to a lack of a. ATP. b. NADPH. c. oxygen. d. Both a and c are correct.

d

The final acceptor of electrons during the light reactions of the noncyclic electron pathway is a. PS I. b. NADP+. c. PS II. d. water. e. ATP.

d

The noncyclic electron pathway, but not the cyclic pathway, generates a. 3PG. b. ATP. c. chlorophyll. d. NADPH.

d

C4 photosynthesis a. is the same as C3 photosynthesis, because it takes place in chloroplasts. b. occurs in plants whose bundle sheath cells contain chloroplasts. c. takes place in plants such as wheat, rice, and oats. d. is an advantage when the weather is hot and dry. e. Both b and d are correct.

e

The ATP and NADPH from the light reactions are used to a. split water. b. cause RuBP carboxylase to fix CO2. c. re-form the photosystems. d. cause electrons to move along their pathways. e. convert 3PG to G3P.

e

The Calvin cycle reactions a. produce carbohydrate. b. convert one form of chemical energy into a different form of chemical energy. c. regenerate more RuBP. d. use the products of the light reactions. e. All of these are correct.

e

C4 plants

fix CO2 in mesophyll cells and then deliver the CO2 to the Calvin cycle in bundle sheath cells.

CAM plants

fix carbon dioxide at night when their stomata remain open

As the electrons pass through the electron transport chain, they help establish a

hydrogen ion gradient

Where does photosynthesis happen?

in the chloroplasts

where are the calvin cycle reactions located?

in the stroma

carbon dioxide fixation occurs in _____ cells

mesophyll

The structure of C3 plants allows RuBP carboxylase to bind with ____ during photorespiration.

oxygen

At the end of the cyclic electron pathway, the energy-spent electron returns to

photosystem I

Electrons from the electron transport chain replace those lost by

photosystem I

In the noncyclic electron pathway, electrons are energized in ____ before they enter ____

photosystem II an electron transport chain

Photosynthesis begins when

pigment complexes within photosystem I and photosystem II absorb radiant energy

Stomata

small openings where CO2 enters the leaf

The ATP and NADPH made in thylakoid membranes pass into the

stroma

The hydrogen ion gradient across the thylakoid membrane is used to

synthesize ATP using an ATP synthase enzyme complex.

G3P is used to

synthesize various molecules, including carbohydrates such as glucose

What are the 2 reactions of photosynthesis?

the light reactions the calvin cycle reactions

2 main portions of a chloroplast

the stroma membranous grana

what is the membranous grana made up of?

thylakoid sacs

Photosynthesis uses solar energy in the ____ range

visible-light

Oxygen is reduced to

water

Where are chlorophyll and other pigments like the carotenoids located?

within the thylakoid membrane