Bioenergetics

Question 1

what is photosynthesis

Answer 1

redox process in which CO2 is reduced to glucose by water which is oxidized to oxygen

an energy conversion process in which energy poor molecules such as CO2 and H2O are converted into energy rich moleucles such as glucose

Question 2

what is the chemical equation for photosynthesis

Answer 2

6CO2 + 12H2O - C6H12O6 + 6O2 + 6H2O

Question 3

what is the wavelength of visible light is effective for photosynthesis

Answer 3

380- 750 nm

Question 4

what are the factors that affect absorbtion of light for photosynthesis

Answer 4

wavelength of light

the photosynthetic pigment

Question 5

what is action spectrum

Answer 5

graph of rate of phtosynthesis against different wavelengths

Question 6

which wavelengths of light are most effective for the process of photosynthesis

Answer 6

blue 430nm - red 670 nm

Question 7

what is a pigment

Answer 7

an substance that absorbs light energy

Question 8

pigments that take part i photosynthesis are present in

Answer 8

thylakoid sheets

Question 9

what are the two major group of pigments

Answer 9

chlorophyll and carotenoids

Question 10

which wavelength of light is absorbed and reflected by chlorophyll

Answer 10

violet blue orange and red are mainly absorbed

green and yellow are least absorbed and reflected

Question 11

two major groups of chlorophyll are

Answer 11

chlorophyll -a and chlorophyll- b

Question 12

what is chlorophyll-a and where is it found

Answer 12

bluish green pigment found in all photosynthetic organisms except photosynthetic bacteria

Question 13

what is chlorophyll-b and where is it found

Answer 13

it is a yellow green pigment found in all photosynthetic organisms except brown, red algae and photosynthetic bacteria

Question 14

which chlorophyll pigments are present in algae

Answer 14

c d e

Question 15

which chlorophyll pigments are in bacteria

Answer 15

becteriochlorophyll

Question 16

what is the chemical formula of chlorophyll-a and chlorophyll- b

Answer 16

C55 H72 O5 N4 Mg

C55 H70 O6 N4 Mg

Question 17

describe the strucuture of chlorophyll

Answer 17

it has a head (hydrophilic) and a tail (hydrophobic)

head is the light absorbing part projected on the surface
head is composed of porphyrin ring with Mg in the center
porphyrin ring is composed of 4 pyrrole rings
pyrrole rings have 4 C and 1N
the pyrrole rings also contain different groups around them

two side chains (phytol and methyl ester) are embedded into the thylakoid membrane to anchor it

Question 18

what is the different between chlorophyll-a and chlorophyll-b structurally

Answer 18

chlorophyll- a has a methyl group whereas chlorophyll-b has a aldehyde group

Question 19

what are carotenoids

Answer 19

terpenoid lipids which are yellow, orange, red and brown pigments

Question 20

which light do carotenoids absorb and where are they seen

Answer 20

blue - violet range of light

seen in leaves before they fall as well as in some flowers and fruits

Question 21

what is the function of carotenoids

Answer 21

act as accessory pigment along with chlorophyll-b and pass light energy to chlorophyll-a

protect chlorophyll-a from excess light

attract insects and birds for pollination and dispersal

Question 22

what are the two types of carotenoids

Answer 22

carotenes and xanthophylls

Question 23

what are carotenes and what is the most widespread carotene

Answer 23

orange -red pigments composed of isoprenoid units found in all photosynthetic eukaryotes

beta carotene

Question 24

what is xanthophyll and its most widely distributed type along with its function

Answer 24

yellow pigment composed of isoprenoid units

lutein which is responsible for yellow color of foliage in autumn

Question 25

what instrument is used to determine absorption of light

Answer 25

spectrophotometer

Question 26

what is absorbtion spectrum

Answer 26

graph which shows absorption of light by a particular pigment

Question 27

which wavelengths of light are absorbed by chlorophyll-a chlorophyll-b and carotenoids

Answer 27

violet-blue (400-470nm) organe-red (630-660nm) 430-500nm

Question 28

describe the composition of photosystems

Answer 28

peripheral part is called antenna complex which consists of accessory pigment (chlorophyll b and carotenoids) the central part is the reaction center which contains chlorophyll-a and associated pigments

Question 29

what is a photosystem

Answer 29

photosynthetic pigments arranged in clusters in thylakoid membrane

Question 30

why does chlorophyll-a have different absorption of light in different photosystems

Answer 30

due to the associated proteins which shift its optimal wavelength

Question 31

what is the absorption of chlorophyll-a in different photosystems

Answer 31

PS 1 is 700nm | Ps 2 IS 680NM

Question 32

what happens when chlorophyll-a absorbs light energy

Answer 32

it is oxidized and releases and electron

Question 33

what are autotrophs

Answer 33

organisms which use inorganic sources for the synthesis of organic compounds

Question 34

air contains how much CO2

Answer 34

0.03-0.04 %

Question 35

what is the role of CO 2 in photosynthesis

Answer 35

it is utilized for dark or light dependent reactions of photosynthesis

Question 36

aquatic photosynthetic organism use which carbon sources

Answer 36

dissolved CO2, bicarbonates and carbonates in water

Question 37

what is the role of water in photosynthesis

Answer 37

it acts as a hydrogen and electron donor in photosynthesis it replaces the electron lost by PS2 2 hydrogen ions are taken up by NADP to form NADPH

Question 38

when was the role of water first reported in photosynthesis and by who

Answer 38

van niel in 1930

Question 39

oxygen from water is used to form what in photosynthesis

Answer 39

oxygen

Question 40

oxgen in CO2 is used to form what in photosynthesis

Answer 40

glucose and water

Question 41

what are the two phases of photosynthesis

Answer 41

light dependent and light independent

Question 42

where does light dependent phase occur

Answer 42

thylakoid membranes

Question 43

what is phosphorylation and chemiosis

Answer 43

the production of ATP during light dependent phase is phosphorylation and is process is called chemiosis

Question 44

describe non-cyclic phosphorylation

Answer 44

predominant pathway used by higher plants both PS1 and PS2 are involved two electron transport chains are involved PS2 absorbs light, emits electron electron flows in ETC to PS1/NADP

Question 45

describe absorption of light by PS2 and its exitation of electron

Answer 45

when two photons strike antenna complex of PS2 two electron become excited and begin to move to reaction center and pass energy to two electrons which become excited these electrons are captured by primary electron acceptor of PS2 chlorophyll becomes an oxidizing agent

Question 46

describe photolysis of water

Answer 46

when water reacts with oxidized state of chlorophyll in photosystem it break up into 2H and 2e and 1/2 O2 the electrons released are transferred to reaction center of PS2

Question 47

describe the process of chemiosis and movement of electron to PS1

Answer 47

excited electrons released from PS2 are captured by electron acceptor (plastoquinone) which they flow through cytochrome complex/electron carrier (Cyt-b6 and Cyt-f) cytochrome complex is also a proton pump and energy of flowing electron is used to pump hydrogen ions into the thylakoid lumen the electrons after losing their energy move to plastocyanin and are then incorporated into PS1 the hydrogen ions in the thylakoid lumen created a proton gradient which activates ATP synthase producing an ATP molecule from a ADP and phosphate

Question 48

describe the absorption of light and its excitation by