ch. 8 | photosynthesis

Question 1

from 8.1

what are the raw materials for photosynthesis? how do these materials enter plants?

Answer 1

• water; absorption via roots
• CO2; absorbed into stomata (openings in leaves)

Question 2

from 8.1

CO2 & water diffuse into _____________

Answer 2

chloroplasts

Question 3

from 8.1

the ________ is a fluid-filled space where CO2 is enzymatically red’d to CO2

Answer 3

stroma

Question 4

from 8.1

membranous disks containing photosynthetic pigments in the chloroplasts are called?

what do these pigments do?

Answer 4

thykaloids

abosrb solar energy

Question 5

from 8.1

carotenoids give photosynthesizing cells a _________ color

Answer 5

yellow to red

Question 6

from 8.1

what are light reactions?

Answer 6

2 sets of reactiona; light-dependent reactions & Calvin cycle reactions (light-independent)

Question 7

from 8.1

what are the functions of the 2 different types of reactions in photosynthesis?

Answer 7

• light reactions release O2
• Calvin cycle (independent) reactions reduce CO2 to a carb

Question 8

from 8.1

this molecule carries hydrogen atoms from light reactions to Calvin cycle reactions

what is another function of this molecule?

Answer 8

NADP+

allows independent reactions to reduce CO2

Question 9

from 8.1

light reactions require the input of light energy, resulting in the generation of _________

Answer 9

NADPH & ATP

Question 10

from 8.2

the colors violet, indigo, blue, and red are absorbed by which pigments?

Answer 10

chlorophyll a & b

Question 11

from 8.2

carotenoids aborb light in what part of the color spectrum?

**careful: ABSORB not GIVE OFF

Answer 11

violet to green

Question 12

from 8.2

light reactions in the thykaloid membrane have 2 electron pathways called _________________. both pathways produce ATP, but which of the pathways also produces NADPH?

Answer 12

• noncyclic & cyclic electron pathways
• the noncyclic pathway

Question 13

a ________ consists of a pigment complex (re: pigments in chloroplasts) & an acceptor in the thykaloid.

what is the function of the pigment complex?

Answer 13

photosystem

serves as an “antenna” for gathering solar energy

Question 14

during the noncyclic electron pathway, energized electrons leave photosystem _____& pass down the ETC leading to the formation of ______

Answer 14

II; ATP

Question 15

from 8.2

_________________ (replaced by PS* II) leave PS I & pass to NADP+ which combines w/ H+ & froms NADPH+

so PS I forms what?

*PS = photosystem

Answer 15

energized electrons

NADPH

Question 16

from 8.2

the process of splitting what molcule provides replacement electrons to PS II?

(this releases H+ ions & oxygen)

Answer 16

water

Question 17

from 8.2

energy released from electrons move H+ ions to from the stroma into the _________________ forming a hydrogen gradient

Answer 17

thykaloid space

Question 18

the ETC carries electrons from which PS to which?

Answer 18

PS II to PS I

Question 19

from 8.2

PS I is adjacent to __________ which redices NADP+ to NADPH

Answer 19

NADP reductase

Question 20

from 8.2

the ATP synthase complex crosses the ___________ & contains an interior channel & protruding ATP synthase that joins ADP + P

Answer 20

thykaloid

Question 21

from 8.2

under high oxygen levels, NADPH levels may accumulate in the cell, so photosynthetic cells can enter the _______________. what’s the difference between this & the noncyclic pathway?

Answer 21

cyclic electron pathway; electrons are recycled back to PS I (so it’s actually a CYCLE)

Question 22

from 8.2

in the cyclic pathway, energized electrons are taken up by __________ & sent down an ETC. spent eletrons return to __________ after the ETC.

what function does this serve in the cyclic pathway?

Answer 22

an electron acceptor; PS I

this is how PS I receives replacement electrons

Question 23

from 8.2

why is the H+ gradient across a thykaloid membrane called a storage of energy?

Answer 23

bc there are more H+ ions in the thykaloid space than in the stroma, ions tend to move down the gradient + release stored energy to fuel ATP synth

Question 24

from 8.2

what is the reaction center?

Answer 24

a particular pair of chlorophyll a molecules. here is where electrons become so energized that they escape & move to acceptors

Question 25

from 8.3

carbs are synthesized during which stage of photosynthesis?

Answer 25

the Calvin cycle

Question 26

from 8.3

what is the first step of the Calvin cycle? what occurs during this step?

Answer 26

carbon dioxide fixation; in order:
- 3 molecules CO2 attached to 3 RuBP
- 3 C6 molecules splits in half –> 6 C3 molecules
- first 3 -carbon molecule is called 3PG

Question 27

from 8.3

which stage of the Calvin cycle uses ATP for energy and accepts electrons and hydrogen ions from NADPH?

Answer 27

carbon dioxide reduction

Question 28

which electron pathway involves only photosystem I?

Answer 28

cyclic pathway

Question 29

during which stage of the Calvin cycle is the starting material _________ regenerated?

Answer 29

third; RuBP