ch. 8 photosynthesis

Question 1

what is the equation for photosynthesis?

Answer 1

6CO2 + 12H2O ——> C6H12O6 + 6H2O + 6O2

Question 2

what specialized leaf tissues tend to be abundant with chloroplasts?

Answer 2

parenchyma and mesophyll

Question 3

what organisms carry out oxygenic photosynthesis?

Answer 3

cyanobacteria, 7 groups of algae, and plants

Question 4

what organisms carry out non-oxygenic photosynthesis?

Answer 4

some bacteria

Question 5

photosynthesis involves what two types of reactions?

Answer 5

light dependent and light independent (calvin cycle)

Question 6

light dependent reactions capture ______ to make ___ and _____.

Answer 6

light energy, ATP, NADPH

Question 7

light independent reactions use energy from ____ and _____ to synthesize_______from__________.

Answer 7

ATP, NADPH, glucose, CO2

Question 8

where do light dependent reactions take place?

Answer 8

thylakoid membrane

Question 9

where do light independent reactions take place?

Answer 9

stroma

Question 10

what do the products of LD do for LI reactions?

Answer 10

they feed them

Question 11

what do thylakoids contain?

Answer 11

chlorophyll a and accessory pigments

Question 12

what is the grana?

Answer 12

stacks of thylakoids

Question 13

what is the stroma?

Answer 13

semiliquid substance surrounding thylakoids

Question 14

what is a photon?

Answer 14

a discrete packet of light energy

Question 15

in a photon, what is the relationship between wavelengths and energy?

Answer 15

inverse relationship

Question 16

what is the photoelectric effect?

Answer 16

removal of an electron from a molecule by light energy

Question 17

when does the photoelectric effect occur?

Answer 17

when photons sufficiently energize electrons

Question 18

what are pigments?

Answer 18

molecules that absorb light

Question 19

what does each pigment have?

Answer 19

a characteristic absorption spectrum

Question 20

what is an absorption spectrum?

Answer 20

the range and efficiency of photon absorbance

Question 21

what is chlorophyll a?

Answer 21

the primary photosynthetic pigment in plants and cyanobacteria

Question 22

what colors of light does chlorophyll a absorb and what color does it appear?

Answer 22

absorbs violet-blue and red light, appears yellow-green

Question 23

what colors of light does chlorophyll b absorb and what color does it appear?

Answer 23

absorbs wavelengths that chlorophyll a does not absorb well; appears blue-green

Question 24

what is chlorophyll b?

Answer 24

secondary or accessory pigment

Question 25

what is the porphyrin ring?

Answer 25

a chlorophyll pigment that is a ring with alternating double and single bonds, with Mg at the center

Question 26

what does a photo system consist of?

Answer 26

1. an antenna complex of 100s of accessory pigment molecules 2. a reaction center of one or more chlorophyll a molecules

Question 27

where is light energy from the antenna complex transferred and what does it cause?

Answer 27

chlorophyll a, causes an electron to become excited and then to be transferred to an adjacent electron acceptor molecule

Question 28

what does it mean for an electron to become excited?

Answer 28

boosted to a higher energy level

Question 29

what does water donate in oxygenic photosynthesis? What does it replace?

Answer 29

an oxygen; the oxygen lost from chlorophyll

Question 30

what are electrons returned to through an ETC? (LDR)

Answer 30

bacteriochlorophyll

Question 31

In some (non-oxygenic) bacteria, a single _________ is used in ________ _________.

Answer 31

photosystem; cyclic photophosphorylation

Question 32

what do light dependent reactions produce?

Answer 32

ATP and H2

Question 33

what three things do cells need to build carbohydrates?

Answer 33

1. Energy (ATP molecules) 2. Redox potential (NADPH molecules) 3. Source of carbon (CO2 gas)

Question 34

how many molecules of CO2 must be fixed for every glucose molecule produced? (calvin cycle)

Answer 34

6

Question 35

how much will it cost to fix CO2 molecules for glucose production?

Answer 35

18 ATP and 12 NADPH

Question 36

_______ is not the immediate product of the Calvin cycle

Answer 36

glucose

Question 37

what is required to make glucose after the calvin cycle?

Answer 37

G3P

Question 38

for every 6 molecules of CO2 fixed, how many G3Ps leave the cycle?

Answer 38

2 (each contains 3 carbons)

Question 39

what is combined to eventually produce 1 glucose in the cytoplasm?

Answer 39

2 G3Ps

Question 40

during the calvin cycle, how much chemical energy is needed to produce a single glucose?

Answer 40

18 ATP and 12 NADPH

Question 41

what are the 2 enzymatic activities of rubisco?

Answer 41

Carboxylation and Photorespiration

Question 42

what is carboxylation?

Answer 42

the addition of CO2 to RuBP (favored under normal conditions)

Question 43

what is photorespiration?

Answer 43

the oxidation of RuBP by O2

Question 44

when is Photorespiration favored?

Answer 44

in hot conditions

Question 45

what does Photorespiration cause the loss of?

Answer 45

CO2

Question 46

when is Carboxylation favored?

Answer 46

under normal conditiions

Question 47

what two molecules compete for the active site on the Rubisco enzyme?

Answer 47

CO2 and O2

Question 48

why do stomata close at night?

Answer 48

to conserve moisture

Question 49

why might stomata close in the day under hot, dry conditions?

Answer 49

to conserve moisture

Question 50

how do C4 plants avoid photorespiration?

Answer 50

by fixing CO2 in a mesophyll cell and then releasing it in a bundle sheath cell where the Calvin Cycle is operational

Question 51

what are CAM plants?

Answer 51

plants where the stomata open only at night

Question 52

why are CAM plants stomata open only at night?

Answer 52

cool, moist conditions prevent excessive water loss but still allow CO2 uptake

Question 53

what happens in photorespiration of CAM plants?

Answer 53

-PEP carboxylase adds CO2 to PEP to produce a 4 carbon malate molecule (carbon fixation only at night). -malate releases CO2 during the day when stomata are closed to conserve moisture. -CO2 is then used by Rubisco in the Calvin cycle (Calvin Cycle during day).

Question 54

what is an example of a CAM plant?

Answer 54

a pineapple