Chapter 7

Question 1

photosynthesis

Answer 1

reduction of CO2 to a carbohydrate using light energy

Question 2

photosynthesis equation

Answer 2

6H2O + 6CO2 + energy (photons) –> C6H12O6 +6O2

Question 3

photosynthesis is carried out by

Answer 3

some bacteria
algae (mostly single celled)
plants (multi celled)

Question 4

what causes algae blooms?

Answer 4

1) nutrients -(usually phosphorus) sewage, farm run off
2) temp- production of toxic compounds
- oxygen consumption by algae and bacteria feeding on dead algae

Question 5

photosynthesis organisms live

Answer 5

in association with some animals

Question 6

in eukaryotes photosynthesis takes place in

Answer 6

the chloroplast

Question 7

stroma

Answer 7

area between the inner membrane and the thylakoids

Question 8

in prokaryotes photosynthesis takes place on

Answer 8

an internally folded membrane

Question 9

light is a type

Answer 9

of photon

Question 10

particles of energy

Answer 10

photons

Question 11

photons vary in

Answer 11

their energy level

Question 12

photos have properties that are

Answer 12

wave like

Question 13

each photon has a defined

Answer 13

energy level and wavelength

Question 14

light is defined as

Answer 14

photons we can see

Question 15

light sources usually have many different types of

Answer 15

photons all which can be potentially be used for photosynthesis

Question 16

interactions between photons and atoms

Answer 16

1. atoms can absorb the energy of photons
2. atoms can give off photons
3. only certain atoms or molecules absorb certain types (wavelength) of photons

Question 17

pigments

Answer 17

molecules that absorb visible light

Question 18

absorption of photons by molecules

Answer 18

electron takes on a higher energy state
the electron is unstable at the higher energy state
in most molecules the electron returns to its original state and emits
1. photons
2. heat (movement of the molecule)

Question 19

pigments involved in photosynthesis

Answer 19

chlorophylls and accessory pigments

Question 20

chlorophylls

Answer 20

main photosynthetic pigment absorbs blue and red light

electrons held loosely by nucleus

Question 21

light absorbtion by pigments

Answer 21

accessory pigments allow photons chlorophyll can’t absorb

Question 22

pigments used in photosynthesis are

Answer 22

organized into photosystems 1 and 2
groups of chlorophyll and accessory pigments
found on the thylakoid membrane

Question 23

how is light energy converted to potential energy

Answer 23

chlorophyll removed from cholroplast
green photons are reflected. other colors are
absorbed
immediately after light is removed
red photons released as electrons return to lower energy state

Question 24

chlorophyll in a chloroplast

Answer 24

electrons that absorb photons are passed to an electron transport chain

Question 25

two stages in photosynthesis

Answer 25

1. light reactions: light energy transferred to electrons: used to make ATP and high energy electron source for:
2. dark reactions: CO2 reduced to a carbohydrate

Question 26

photosystem 1

Answer 26

electrons excited by photon energy can take one of two paths

Question 27

photosystem two paths:

Answer 27

cylic path

non cyclic path

Question 28

cyclic path

Answer 28

electrons travel through an electron transport chain back to photosystem 1
the process produces ATP by chemiosmosis

Question 29

non cyclic path

Answer 29

electrons passed to an electron carrier

Question 30

light reactions

Answer 30

energy from photons are directed towards chlorophyll
energy level of chlorophyll electrons is increased and
causes them to be lost from the chlorophyll molecule

Question 31

photosystem 2

Answer 31

electrons lost from the chloroohyll are replaced by electrons from H2O
electrons are passed down an electron trasnport chain
H+ is actively transported from the stroma into thyacoid compartment

Question 32

photosystem 2 continued

Answer 32

H+ passes back into the stoma through ATP synthase, producing ATP
at the end of the electron transport chain the electrons are passed to photosystem 1
photosystem 2 is only involved in ATP production

Question 33

summary of light reactions

Answer 33

inputs:                 products: 
photons               O2 
H2O                     ATP
ADP                      NADPH
P
NADP+

Question 34

dark reactions (calvin cycle) 3 phases

Answer 34

1. carbon fixation
2. reduction
3. regeneration

Question 35

1. carbon fixation

Answer 35

Co2 combines with 5 carbon sugar

(RuBP) and splits into 2 molecules

Question 36

2. reduction

Answer 36

electrons are donated to 3 carbon molecules from NADPH
energy from ATP is required
one of the 3 carbon products used to produce glucose

Question 37

3. regeneration

Answer 37

one of the 3 carbon compounds used to make new RuBP

requires ATP

Question 38

summary of dark reactions

Answer 38

inputs: outputs:
CO2 G3P ( 3 carbon molecule)
NADPH
ATP energy ADP
P
NADP+

Question 39

carbs

Answer 39

carbohydrates made in photosynthesis provide the carbon source and energy for all other organic molecules
photosynthesis resulted in a rapid increase in O2 about 2 billion years ago

Question 40

light vs dark

Answer 40

light formed under aerobic conditions
dark formed under anaerobic conditions
dark is temp sensitive
light is not

Question 41

photostasis

Answer 41

balance between light and dark reactions
if reactions centers remain reduced, they will be damaged
organisms build photosynthetic systems to balance light and dark reactions
as temp drop some organisms produce protective pigments, others reduce their chlorophyll levels

Question 42

plant lose

Answer 42

water when they take in CO2

Question 43

stomata

Answer 43

regulate gas exchange in leaves and prevent water loss

Question 44

plants may

Answer 44

not photosynthesize to prevent water loss