Chapter 8: Photosynthesis

Question 1

photosynthesis

Answer 1

energy within light is captured and used to synthesize carbohydrates

Question 2

biosphere

Answer 2

regions on the surface of the Earth and atmosphere where living organisms exist

Question 3

energy cycle

Answer 3

cells use organic molecules for energy and plants replenish those molecules using photosynthesis

Question 4

heterotroph

Answer 4

must eat food (organic molecules from their environment) to sustain life

Question 5

autotroph

Answer 5

makes organic molecules from inorganic ones

Question 6

photoautotroph

Answer 6

use light as a source of energy

Question 7

chloroplast

Answer 7

organelle in plants and algae that carries out photosynthesis

Question 8

stomata

Answer 8

carbon dioxide enters and oxygen exits leaf through here

Question 9

inter-membrane space

Answer 9

separates inner and outer membrane

Question 10

thylakoid membrane

Answer 10

contains pigment molecules, encloses thylakoid lumen

Question 11

granum

Answer 11

stack of thylakoids

Question 12

stoma

Answer 12

fluid filled region between thylakoid membrane and inner membrane

Question 13

two stages of photosynthesis

Answer 13

light reactions in thylakoid membrane

calvin cycle in stoma

Question 14

absorption spectrum

Answer 14

wavelengths that are absorbed by different pigments

Question 15

action spectrum

Answer 15

rate of photosynthesis by whole plat at specific wavelengths

Question 16

photosystem 1

Answer 16

primary role to make NADPH

addition of H+ to NADP+ contributes to H+ gradient by depleting H+ from stroma

Question 17

photosystem 2

Answer 17

first step in photosynthesis, excite ground state electrons

light excites pigment molecules in PS 2 and PS 1

Question 18

photophosphorylation

Answer 18

chemiosmotic mechanism that causes ATP synthesis, driven by the flow of H+ from thylakoid lumen into stroma

Question 19

three chemical products from photosynthesis

Answer 19

oxygen
NADPH
ATP

Question 20

noncyclic

Answer 20

electrons begin at PS 2 and eventually transfer to NADPH, linear process
produces ATP and NADPH in equal amounts

Question 21

cyclic photophosphorylation (electron flow)

Answer 21

electron cycling releases energy to transport H+ into lumen driving ATP synthesis

Question 22

homologous genes

Answer 22

similar because they are derived from a common ancestral gene

Question 23

photosystem 2 steps

Answer 23

1 - light harvesting complex

2 - reaction center

Question 24

light harvesting complex

Answer 24

directly absorbs photons, energy transferred via resonance energy transfer

Question 25

reaction center

Answer 25

electron transfers to primary electron acceptor and captured

Question 26

z scheme

Answer 26

zig-zag shape of the energy curve; photosynthesis involves increases and decreases in the energy of an electron as it moves from PS 2 through PS 1 to NADPH

Question 27

Calvin cycle (Calvin-Benson cycle)

Answer 27

requires massive input of energy (18 ATP + 12 NADPH) product is G3P

Question 28

Calvin cycle phases

Answer 28

carbon fixation
reduction and carbohydrate reduction
regeneration of RuBP

Question 29

carbon fixation

Answer 29

CO2 incorporated into RuBP using rubisco enzyme; product is a six-carbon intermediate that splits into two 3-phosphoglycerate molecules (3PG)

Question 30

reduction and carbohydrate reduction

Answer 30

6CO2 –> 12 G3P, ATP used to convert 3PG into 1,3 biphosphoglycerate (1,3 BPG), NADPH electrons reduce it to G3P

Question 31

regeneration of RuBP

Answer 31

10 G3P are converted into 6 RuBP using 6 ATP

Question 32

variations in photosynthesis

Answer 32

environmental conditions can influence both the efficiency and the way the Calvin cycle works (light intensity, temperature, water availability, CO2 availability)

Question 33

photorespiration

Answer 33

O2 added to RuBP and releases CO2, likely in hot and dry environments, essentially Calvin cycle but the sugar is recycled and not created, happens to C3 plants

Question 34

carboxylase

Answer 34

bonds to CO2

Question 35

oxygenase

Answer 35

bonds to O2

Question 36

C3 plants

Answer 36

make 3PG and cannot survive in deserts due to performing photorespiration and wasting energy

Question 37

C4 plants

Answer 37

evolved a mechanism to minimize photorespiration

Question 38

mesophyll cells

Answer 38

CO2 enters via stomata and 4 carbon compound formed (PEP carboxylase doesn’t perform photorespiration)

Question 39

bundle-sheath cells

Answer 39

4 carbon molecule transferred that releases steady supply of CO2, minimizing photorespiration