Chapter 10

Question 1

Chloroplasts

Answer 1

Organelle where photosynthesis occurs

Question 2

Autotrophs

Answer 2

“Self-feeders”. The producers of the biosphere that use up CO2. Almost all plants

Question 3

Heterotrophs

Answer 3

Obtain organic material from other organisms. Consumers. Depend on photoautotrophs for food and O2

Question 4

Photoautotroph

Answer 4

Organisms that can use light energy to sustain themselves - plants mostly, but can also be multicellular alga, unicellular eukaryotes, cyanobacteria, and Purple Sulphur Bacteria

Question 5

________ are the major locations of photosynthesis in plants

Answer 5

leaves

Question 6

mesophyll

Answer 6

Cells where chloroplasts are mainly found, the interior tissue of the leaf

Question 7

Each mesophyll cell contains ________

Answer 7

30-40 chloroplasts

Question 8

Stroma

Answer 8

The dense fluid bound inside two membranes of a chloroplast

Question 8

Stomata

Answer 8

microscopic pores in a leaf where CO2 and O2 enter and exit

Question 9

Thylakoids

Answer 9

The connected sacs in the chloroplast that compose a third membrane system. These may be stacked in columns called grana

Question 11

Chlorophyll

Answer 11

The pigment that gives leaves their green color and resides in the thylakoid membranes

Question 12

Photosynthesis reaction formula

Answer 12

6 CO2 + 12 H2O + Light Energy —> C6H12O6 + 6 02 + 6 H2O

Question 13

Splitting H2O

Answer 13

Chloroplasts split H2O into hydrogen and oxygen, incorporating the electrons of hydrogen into sugar molecules and releasing oxygen as a by-product

Question 14

Photosynthesis as a redox process

Answer 14

Photosynthesis reverses the direction of electron flow compared to respiration. Photosynthesis is a redox process in which H2O is oxidized and CO2 is reduced. Photosynthesis is an endergonic process where the energy boost is provided by light

Question 15

The Two Stages of Photosynthesis

Answer 15

Light Reactions (photo) and the Calvin Cycle (synthesis)

Question 16

The light reactions

Answer 16

1) Split H2O
2) Release O2
3) Reduce the electron acceptor NADP+ to NADPH
4) Generate ATP from ADP by photophosphorylation

Question 17

photophosphorylation

Answer 17

The process of converting light energy into chemical energy, such as ATP, in chloroplasts during photosynthesis

Question 18

Chemiosmosis

Answer 18

the process where ions, typically hydrogen ions (H+) move across a semipermeable membrane down their electrochemical gradient

Question 19

Carbon Fixation

Answer 19

The beginning of the Calvin cycle that incorporates CO2 into organic molecules

Question 20

Light Reactions

Answer 20

Create ATP and NADPH which are then used in the Calvin Cycle

Question 21

Nature of Sunlight

Answer 21

Electromagnetic Energy; travels in waves that are created by disturbances of electrical and magnetic fields

Question 22

Photons

Answer 22

A light particle

Question 22

Electromagnetic Spectrum

Answer 22

The spectrum of light; ranges from less than a nanometer (gamma rays) to more than a kilometer (radio waves); The segment most important to life is 380 nm to 740 nm (visible light)

Question 23

Spectrophotometer

Answer 23

An instrument that can measure a pigments ability to absorb various wavelengths of light

Question 24

Absorption spectrum

Answer 24

A graph that plots a pigment’s light absorption versus wavelength

Question 25

chlorophyll a

Answer 25

the key light-capturing pigments in chloroplasts (green); special because they can transfer an excited electron to a different molecule

Question 26

chlorophyll b

Answer 26

An accessory pigment that helps absorb light (yellow-green)

Question 27

Action Spectrum

Answer 27

Profiles the relative effectiveness of different wavelengths of radiation in driving process

Question 28

Carotenoids

Answer 28

Other accessory pigments in a chloroplast; Hydrocarbons that are usually yellow and orange because they absorb violet and blue-green shades

Question 29

Excitation

Answer 29

A photon that matches that pigments required wavelength is absorbed by the pigment, exciting an electron and raising it up one or more orbitals. This increases the energy but makes the pigment unstable. When the electron drops back down, it releases energy

Question 30

photosystem

Answer 30

consists of a reaction-center complex surrounded by light-harvesting complexes

Question 31

Reaction-center complex

Answer 31

an association of proteins holding a special pair of chlorophyll a molecules and a primary electron acceptor

Question 32

Light-harvesting complex

Answer 32

consists of pigment molecules (chlorophyll a and b, carotenoids, and xanthophyll b) bound to proteins; transfer the energy of photons to the chlorophyll a molecules in the reaction-center complex

Question 33

Primary electron acceptor

Answer 33

in the reaction center; accepts excited electrons and is reduced; transfer of an electron from a chlorophyll a molecule to the primary electron acceptor is the first step of light reactions

Question 34

Photosystem II (PS II)

Answer 34

functions first; The reaction-center chlorophyll a of PS II is called P680 because it is best at absorbing a wavelength of 680 nm

Question 35

Photosystem I (PS I)

Answer 35

functions second; The reaction-center chlorophyll a of PS I is called P700 because it is best at absorbing a wavelength of 700 nm

Question 36

Linear electron flow

Answer 36

the primary pathway; involves both photosystems; produces ATP and NADPH using light energy

Question 37

First step in linear electron flow

Answer 37

A photon hits a pigment in a light-harvesting complex of PS II, and its energy is passed among pigment molecules until it excites P680

Question 38

Second step in linear electron flow

Answer 38

An excited electron from P680 is transferred to the primary electron acceptor (we now call it P680+)

Question 39

Third Step in Linear electron flow

Answer 39

H2O is split by enzymes, and the electrons are transferred from the hydrogen atoms to P680+, thus reducing it to P680 (P680+ is the strongest known biological oxidizing agent; The H+ are released into the thylakoid space; O2 is released as a by-product)

Question 40

Fourth Step in Linear Electron Flow

Answer 40

Each electron “falls” down an electron transport chain from the primary electron acceptor of PS II toPS I. Energy released by the fall drives the creation of a proton gradient across the thylakoid membrane

Question 41

Fifth Step of Linear Electron Flow

Answer 41

Potential energy stored in the proton gradient drives production of ATP by chemiosmosis

Question 42

Sixth Step of Linear Electron Flow

Answer 42

In PS I (like PS II), transferred light energy excites P700, which loses an electron to the primary electron acceptor (chlorophyll A0)

Question 43

Seventh Step in Linear Electron Flow

Answer 43

P700+ (P700 that is missing an electron) accepts an electron passed down from PS II via the electron transport chain

Question 44

Eighth Step of Linear Electron Flow

Answer 44

NADP+ reductase catalyzes the transfer of electrons to NADP+, reducing it to NADPH (The electrons of NADPH are available for the reactions of the Calvin Cycle; This process also removes an H+ from the stroma)

Question 45

Glyceraldehyde 3-phosphate

Answer 45

The sugar produced in the Calvin Cycle