Chapter 10: Photosynthesis

Question 1

Photosynthesis

Answer 1

conversion process that transforms energy from sunlight into chemical energy that is stored in sugars and other organic molecules, nourishes the entire living world both directly and indirectly

Question 2

Autotrophs

Answer 2

self feeders, sustain themselves without eating anything derived from other living things, produce organic molecules from CO2 and other inorganic molecules, big source of organic compounds, producers

Question 3

Photoautotrophs

Answer 3

organisms that use light as their energy source to produce and synthesize energy for making organic substances

Question 4

Heterotrophs

Answer 4

unable to make their own food, live off of compounds made by other organisms, occurs when animals eat plants or other organisms

Question 5

Decomposers

Answer 5

heterotrophs that feed off of remains of other organisms like feces and fallen leaves

Question 6

Chloroplast

Answer 6

eukaryotic organelle that absorbs energy from sunlight and uses it to drive the synthesis of organic compounds from CO2 and H2O

Question 7

Endosymbiont Theory

Answer 7

original chloroplast was a photosynthetic prokaryote that lived inside a eukaryotic cell

Question 8

Mesophyll

Answer 8

interior tissue of a leaf, chloroplasts are mainly found in mesophyll cells

Question 9

Stomata

Answer 9

microscopic pores that allows CO2 to enter and O2 to exit the leaf

Question 10

Chlorophyll

Answer 10

green pigment that gives plants their color, resides in the thylakoid membranes of chloroplasts

Question 10

Stroma

Answer 10

dense fluid surrounded by 2 membranes in chloroplasts

Question 11

Chemical Equation for Photosynthesis

Answer 11

6CO2 + 12H2O + light energy —> C6H12O6 + 6O2 + 6H2O

Question 11

Thylakoid

Answer 11

suspended within the stroma, segregates stroma from the thylakoid space inside the sacs of thylakoids

Question 12

NADP+

Answer 12

acceptor that takes on H+ ions from water after the chlorophyll drives an electron transfer, temporary storage

Question 12

2 Stages of Photosynthesis

Answer 12

1: light reactions (photo)
2: dark reactions (synthesis)

Question 13

NADPH

Answer 13

reduced from NADP+ by adding a pair of electrons along with an H+ molecule

Question 14

Photophosphorylation

Answer 14

process in which light reactions generate ATP and use chemiosmosis to phosphorylate ADP + P

Question 15

The Calvin Cycle

Answer 15

incorporates CO2 from the air into organic molecules that are already present in the chloroplast, initial incorporation of carbon into organic compounds is known as carbon fixation, the cycle then continues to reduce the foxed carbon into carbohydrate

Question 16

Wavelength

Answer 16

distance between crests of electromagnetic waves, range from one nanometer to kilometers

Question 17

Electromagnetic Spectrum

Answer 17

entire range of radiation

Question 18

Visible Light

Answer 18

light that can be detected by human eyes in various colors

Question 19

Photons

Answer 19

the type of discrete particles consisting of light, not tangible objects, have a fixed quantity of energy, short wave means high energy, long wave means low energy

Question 19

Pigments

Answer 19

substances that absorb visual light

Question 19

Spectrophotometer

Answer 19

instrument that measures the ability of a pigment to absorb carious wavelengths of a light, directs beams of lights of different wavelengths through a solution of pigments and measures the fraction of light transmitted at each wavelength

Question 20

Absorption Spectrum

Answer 20

a graph plotting a pigments light absorption vs. wavelength

Question 21

3 Types of Pigments in Chloroplasts

Answer 21

CHlorphyll A: the key light capturing pigments that participates directly in light reactions
Chlorophyll B: accessory pigment, specifically pigments called carotenoids

Question 22

Action Spectrum

Answer 22

confirms that violet-blue and red wavelength lights are best for photosynthesis, profiles the relative effectiveness of different wavelengths of radiation in driving photosynthesis, illuminates chloroplasts with light of different colors

Question 23

Carotenoids

Answer 23

accessory pigment, hydrocarbons that are various shades of yellow and orange because they absorb violet-blue and green light

Question 24

Photoprotection

Answer 24

important function of carotenoids, absorb and dissipate excessive light energy that would damage the chlorophyll or interact with oxygen

Question 25

Photosystem

Answer 25

composed of a reaction center complex surrounded by several light harvesting complexes

Question 26

Reaction Center Complex

Answer 26

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

Question 26

Light Harvesting Center

Answer 26

consists of various pigments bound to proteins

Question 27

Primary Electron Acceptor

Answer 27

molecule capable of accepting electrons and becoming reduced

Question 28

Types of Photosystems

Answer 28

PS II: also known as P680 because it is best at absorbing 680nm light, functions in light reactions
PS I: also known as P700 because it is best at absorbing 700nm light, functions in light reactions

Question 29

Linear Electron Flow

Answer 29

flow of electrons through the photosystems and other molecular components built into the thylakoid membrane, occurs during the light reactions

Question 30

Cyclic Electron Flow

Answer 30

alternative path for photoexcited electrons, uses PS1 and not PS2, short circuit: electrons cycle back from ferredoxin to the cytochrome complex then via plastocyanin molecule to a P700 chlorophyll in PSI, no production of NADPH and no release of O2

Question 31

The Calvin Cycle

Answer 31

takes place in the stroma, anabolic, carbon enters the cycle as CO2 and exits as a form of sugar, spends ATP and consumes NADPH, sugar produced is called glyceraldehyde 3-phosphate or G3P

Question 32

G3P

Answer 32

to make one molecule of G3P, the calvin cycle must take place 3 times making 3CO2 molecules per turn

Question 33

3 Phases of Calvin Cycle

Answer 33

Carbon Fixation: incorporates each CO2 molecule by attaching it to a 5-carbon sugar called RuBP, Rubisco enzyme catalyzes the first step, results in 3-phosphoglycerate, a 6-carbon sugar
Reduction: each molecule of 3-phosphoglycerate gets a P group from ATP and turns into 3-biphoshoglycerate, 2e- donated from NADPH reduces 1,3biphosphoglycerate to the aldehyde group of G3P
Regeneration: a series of complex reactions, carbon skeletons of 5 molecules of G3P are rearranged by the last step into 3 molecules of RuBP, spends 3 more molecules of ATP in this process, RuBP is back to receive CO2 and the cycle continues

Question 34

For Net Synthesis of One G3P Molecule

Answer 34

9 molecules of ATP and 6 molecules of NADPH are consumed in the calvin cycles

Question 35

Photorespiration

Answer 35

process in which plants perform self-saving techniques to stay alive, but which also cause problems, occurs in the light reaction and uses O2 while producing CO2, uses ATP but does not make it, produces no sugar, decreases photosynthetic output by taking materials from the calvin cycle and using it to release otherwise foxed carbon

Question 36

C3 Plants

Answer 36

first organic product of carbon is fixed in a 3-carbon compound called 3-phosphoglycerate, includes plants like rice, wheat, and soybeans

Question 37

C4 Plants

Answer 37

preface the calvin cycle with an alternate mode of carbon fixation that forms 4-carbon compounds as its first product, plants include sugarcane, corn, and certain grasses

Question 38

Bundle Sheath Cells

Answer 38

photosynthesis starts in mesophyll cells but ends here, cells that arrange themselves into tightly packed sheaths around the veins of the leaf

Question 39

Mesophyll Cells in C4 Plants

Answer 39

loosely arranged, bundled in between sheath cells and leaf surface, CO2 is incorporated into organic compounds that then move into bundle sheath cells

Question 40

PEP Carboxylase

Answer 40

enzyme present in only mesophyll cells, high affinity for CO2

Question 41

Crassulacean Acid Metabolism (CAM)

Answer 41

mode of carbon fixation, mesophyll of these plants store the organic acids they make during the night in vacuoles until they need it in the morning and day time