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photosynthesis Flashcards

1
Q

Joseph priestly

A

in 1770 revealed the essential role of oxygen in the growth of green plants, inn 1774, hypothesised that plants restore the air that animals breath in and burning candles remove

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2
Q

Joseph priestly

A

in 1770 revealed the essential role of oxygen in the growth of green plants, inn 1774, hypothesised that plants restore the air that animals breath in and burning candles remove

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3
Q

jan ingenhouz

A

showed that sunlight is essential to the plant process and with the help of an aquatic plant revealed that it is only the green parts of plant that release oxygen

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4
Q

julius von sachs

A

1854 revealed that glucose in the form of starch is formed in chloroplasts in green parts of plants

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5
Q

t.w englemann

A

split light into spectral components then illuminated green algae cladophora and saw that oxygen evolved in the places of blue and red region of light, action spectrum of photosynthesis described, as well as of chlorophyll a and b

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6
Q

cornelius van niel

A

on his studies of purple and green bacteria, demonstrated that photosynthesis is a light dependent reaction in which hydrogen from a suitable oxidisable compound reduces co2 to carbs, oxygen evolved comes from h20 not co2

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7
Q

mesophyll cells have a large number of

A

chloroplasts

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8
Q

position of chloroplasts with respect to chlorophylls

A

usually align themselves wala of mesophyll cells such that they get maximum incident

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9
Q

labour in chloroplasts

A

clear division of labour in chloroplasts

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10
Q

system responsible for trapping light energy and synthesizing atp and nadp

A

membrane system

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11
Q

light reactions

A

trapping light energy, atp and nadp synthesis

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12
Q

enzymatic reactions synthesizing sugar which is formed into starch occurs in

A

stroma

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13
Q

dark reactions

A

enzymatic reactions synthesizing sugar and forming starch

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14
Q

light reactions are also called; dark reactions are also called

A

photochemical ; carbon reactions

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15
Q

are dark reactions light dependent or independent

A

dependent on the products of light reaction, atp and nadp

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16
Q

chlorophyll a

A

bright or blue green

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17
Q

chlorophylls b

A

yellow green

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18
Q

xanthophylls

A

yellow

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19
Q

carotenoids

A

yellow to yellow orange

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20
Q

what are pigmentw

A

substances that have an ability to absorb light at different wavelengths

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21
Q

photosynthesis occurrs in the range

A

400-700 nm- photosynthetic active radiation

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22
Q

where is chlorophylla effective

A

more effective in red region than blue region

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23
Q

maximum absorption takes place

A

in blue and red region

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24
Q

chief pigment associated with photosynthesis

A

chlorophyll a

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25
Q

accessory pigments

A

thylakoid pigments like chlorophyll b, xanthophylls, carotenoids, absorb light and transfer energy to chlorophyll a, enable wider range of wavelength of incoming light to be utilised for photosynthesis, protect chlorophylls a firm photo oxidation

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26
Q

what is photoxidation

A

damage to others due to high light intensity

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27
Q

light reactions include

A

light absorption, water splitting, oxygen release, formation of high energy chemical intermediates atp and nadph

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28
Q

pigments system are divided into two parts

A

light harvesting complex and reaction centre

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29
Q

LHC is associated with

A

ps1 and ps2

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30
Q

components of lhc

A

made up of accessory pigments molecules bound to proteins

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31
Q

ps of lhc has all pigments

A

except a forming an lhc also called as antenna

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32
Q

function of lhc

A

help to make photosynthesis more efficient by absorbing light at different wavelengths

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33
Q

reaction centre is composed of

A

chlorophylls a

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34
Q

chlorophylls a converts

A

light energy to chemical energy

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35
Q

the reaction centre is different/same

A

different in both photosystems

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36
Q

in ps 1 chlorophyll a has absorption peak at

A

700 nm

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37
Q

at ps 2 chlorophyll had absorption peak at

A

680 nm

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38
Q

electron transport system is also called as

A

oxidative phosphorylation

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39
Q

fixed electric carrier

A

cytochrome b-6f

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40
Q

mobile electron carrier

A

plastoquinome

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41
Q

copper containing mobile electron carrier

A

plastocyanin

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42
Q

primary electron acceptor in ps2

A

pheophytin

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43
Q

primary electron acceptor in ps 1

A

ferrodoxin reducing substrate

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44
Q

movement of electrons in non cyclic ets

A

downhill in terms of oxidation reduction or redox potential scale

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45
Q

which has higher redox potential frs or pheophytin

A

frs

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46
Q

nadph is reduced to nadp + h where is the h displaced

A

pumped to stroma

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47
Q

function of plastoquinome

A

pumped h+ from stroma to lumen

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48
Q

electron from frs is passed onto ; effect

A

nadph ; reduced to nadp+h

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49
Q

z schemes shaped is formed when electron carriers are arranged in

A

sequence of redox potential scale

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50
Q

splitting of water is associated with

A

ps2

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51
Q

net products of photosynthesis

A

oxygen

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52
Q

electrons needed to replace those removed by ps 1 is provided by

A

ps2

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53
Q

splitting of water occurrs

A

inner side of thylakoid membrane

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54
Q

living organisms extract energy from oxidisable compound and store in form of

A

bond energy

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55
Q

process by which atp is synthesized by cell is called

A

phosphorylation

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56
Q

phosphorylation occurrs in

A

mitochondria and chloroplast

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57
Q

photo phosphorylation

A

synthesis of atp and adp and inorganic phosphate in presence of light

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58
Q

which ps works first in photo phosphorylation

A

ps 2

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59
Q

when is atp formed in z scheme

A

when electron is carried from plastoquinome to cyt-b6f

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60
Q

when only ps 1 is functional electron transport chain

A

circulated through cyclic form

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61
Q

where does cyclic phosphorylation occur

A

stroma lamellae

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62
Q

ps 1, 2 is present/absent in

A

both present in membrane and grana membrane but stroma lamellae membrane lacks ps 2 and nadp reductase enzyme

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63
Q

does cyclic ets result in nadph synthesis

A

no

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64
Q

range in which cyclic phosphorylation occur

A

above 680 nm

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65
Q

chemiosmotic hypothesis

A

explaine how atp is synthesized in chloroplasts, given by p Mitchell

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66
Q

atp synthesis is linked to

A

development of proton gradient across thylakoid membrane

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67
Q

protom accumulation in photosynthesis is towards

A

inner side of thylakoid membrane

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68
Q

splitting of water place

A

on inner side of thylakoid membrane

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69
Q

h or proton produced by splitting of water accumulates in

A

lumen of thylakoid

70
Q

primary acceptor of electron is located in

A

outer side of membrane

71
Q

h from plastoquinome is released in

A

inner side of lumen of thylakoid

72
Q

nadp reductase is located

A

on stroma side of thylakoid membrane

73
Q

with the proton gradient there is a measurable decrease in

A

ph of lumen

74
Q

breakdown of proton gradient leads to

A

atp synthesis

75
Q

the gradient is broken due to

A

movement of protrons from stroma through transmembrane channel of CF0 of atp synthase

76
Q

atp synthase enzyme consists of two parts

A

cf0, Cf1

77
Q

cf0

A

embedded in thylakoid membrane , carries out facilitated diffusion is proton

78
Q

cf1

A

protrudes on outer surface, faces stroma

79
Q

breakdown of gradient; cf1

A

provides enough energy to cause a confirmational change in cf1 which makes the atp synthase synthesizer several molecules of atp

80
Q

chemiosmosis requires

A

a proton gradient, pump, atp synthase, membrane

81
Q

energy is used to

A

pump protons, make a gradient or a high concentration of protons in lumen

82
Q

chemical intermediates in chemiosmotic

A

atp and nadph are used immediately in the biosynthetic reaction in stroma

83
Q

result of o2 after light reaction

A

diffuses out of chloroplast

84
Q

biosynthetic phase of photosynthesis

A

synthesis of sugar

85
Q

dark reaction also carried

A

biosynthetic phase

86
Q

biosynthetic phase is dependent on

A

products of light reaction atp nadp ,co2 and water

87
Q

what led to the discovery of the first co2 fixation product

A

the use of radioactive c14 in algal p photosynthesis

88
Q

what was the first co2 fixation product

A

3 carbon organic acid

89
Q

3 carbon organic acid

A

3 phosphoglyceric acid

90
Q

4 carbon organic acid as the product o of co2 fixation

A

oxaloacetic acid

91
Q

co2 assimilation is of two types

A

c3 and c4 pathway

92
Q

c3 pathway

A

co2 fixation product is 3c

93
Q

c4 pathway

A

co2 fixation product is 4c

94
Q

how many carbon atoms would a molecule have which after accepting co2 has 3 carbons of pga

A

5 carbon RuBP

95
Q

Calvin cycle occurrs in what manner

A

cyclic

96
Q

what is regenerated in calvin cycle

A

RuBP

97
Q

in which plants does calvin cyclce occur

A

all p photosynthetic plants

98
Q

three steps of calvin cycle

A

carboxylation, reduction , regeneration

99
Q

what is carboxylation

A

fixation is co2 into a stable organic intermediate

100
Q

most crucial step of calvin cycle involves

A

fixation of co2 for RuBP, carboxylation

101
Q

carboxylation of RuBP is catalysed by

A

RuBP carboxylase

102
Q

carboxylation of RuBP results in

A

formation of 2 molecules of 3pga

103
Q

nature of RuBP carboxylase

A

oxygenation and carboxylation c/a RuBP carboxylase- oxygenase

104
Q

steps that lead to formation of glucose

A

utilisation of 2 molecules of atp for phosphorylation and two of nadph for reduction per co2 molecule fixed

105
Q

how many molecules of co2 ,atp and nadph and turns are required for formation of one molecule of glucose

A

6 co2 molecule, 2 atp per molecules of co2=12 atp, 2 nadph per molecule of co2= 12 nadph, 6 turns of cycle

106
Q

regeneration of component is crucial if the cycle is to continue uninterrupted

A

co2 acceptor molecule RuBP

107
Q

regeneration step requires how many atp, and what for

A

1 atp for phosphorylation to form RuBP

108
Q

for every co2 molecule entering the calvin cycle , atp, nadph required

A

3 atp and 2 nadph are required

109
Q

how many molecules of atp are required to make 1 glucose

A

18 atp

110
Q

how many molecules of nadph are required to make 1 glucose

A

12 nadph

111
Q

how many co2 are fixated to make 1 glucose

A

6 co2

112
Q
A
113
Q

c4 pathway occurs in plants which live in

A

dry tropical regions

114
Q

main biosynthetic pathway is c4 plants

A

c3 cyclce

115
Q

how are c4 plants different than c3 plants

A

different leaf anatomy, tolerate higher temperature, lack photo respiration, respond at higher light intensity, greater productivity of biomass

116
Q

particularly large cells around vascular bundle on c4 plants

A

bundle sheath cells

117
Q

leaves having bundle sheath cells around vascular bundle

A

kranz anatomy

118
Q

bundle sheath cells

A

May form several layers around vascular bundle, large number of chloroplasts, no intercellular spaces, thick walls impervious to gaseous exchange

119
Q

examples of c4 plants

A

maize, sorghum

120
Q

c4 pathway also called

A

hatch and slack pathway

121
Q

primary co2 acceptor molecule in c4 pathway present in

A

pep, present in mesophyll cells

122
Q

pep undergoes carboxylation form; under influence of enzyme

A

oaa;pep carboxylase

123
Q

mesophyll cells lack

A

rubisco enzyme

124
Q

bundle sheath cells lack

A

pepcase enzyme

125
Q

oaa forms ____ in c4 pathway

A

malic or aspartic acid in mesophyll cells

126
Q

malic/Aspartic acid is transported to

A

bundle sheath cells

127
Q

c4 acid decarboxylated to form

A

3c molecule and co2

128
Q

3c molecule is transported back to

A

mesophyll where it is converted to pep again

129
Q

the co2 released in bundle sheath cells enters

A

c3 pathway

130
Q

where does calvin pathway occurs in c3 plants

A

all mesophyll cells

131
Q

where does calvin pathway occurs in c4 plants

A

only in bundle sheath cells

132
Q
A
133
Q

rubisco is characterized by

A

the fact that it’s active site can with both co2 and o2

134
Q

rubisco has greater affinity for___ under the condition

A

co2 when the ration ratio of co2 and o2 is nearly equal

135
Q

binding of rubisco with co2 or o2 can be described as

A

competitive

136
Q

what determines whether co2 binds with rubisco or o2

A

relative concentration of o2 and co2

137
Q

in c3 plants rubisco binds with o2 hence

A

co2 fixation is decreased

138
Q

in photo respiration rubp binds with o2 to form

A

1 molecule of phosphogllycolate, and phosphoglycerate(2c)

139
Q

photorespiration does not lead to synthesis of ; instead

A

atp, sugar; results in release of co2 with utilisation of atp

140
Q

why does photorespiration not occur in c4 plants

A

they have a mechanism that increases the intracellular concentration of co2 at ensure site this occurs when c4 acid is decarboxylated in bundle sheath cells to release co2

141
Q

what does the i inactivity of photorespiration ensure

A

that rubisco functions as a carboxylase- minimising oxygenase activity

142
Q

photorespiration can be called as

A

wasteful oxygenation reaction

143
Q

how do the internal and external factors affect photosynthesis

A

simultaneously when a plant photosynthesizes

144
Q
A
145
Q

rate of photosynthesis is very important in determining

A

the yield of plants like crop plants

146
Q

photosynthesis is under the influence of several factors both

A

internal (plant) and external

147
Q

plant factors includw

A

number, age, size, orientation of leaves, mesophyll cells, chloroplasts, internal co2 concentration, amount of chlorophylls

148
Q

internal factors are dependent on

A

genetic disposition and growth of plant

149
Q

external factors include

A

availability of light, temperature, co2 concentration and water

150
Q

rate of photosynthesis at any point is determined by

A

the factor available at sub optimal levels

151
Q
A
152
Q

what kind of relation does incident light have with co2 fixation rates at low light intensity

A

linear relationship

153
Q

light saturation occurrs at

A

10 percent of full sunlight

154
Q

light is rarely a limiting factor except for

A

plants in shade, dense forests

155
Q

increase incident light beyond a point causes

A

breakdown of chlorophylls a and decrease in photosynthesis

156
Q

co2 as a factor

A

Major limiting factor

157
Q
A
158
Q

concentration of co2 in atmosphere

A

0.03 to 0.04 percent

159
Q

increase in concentration of co2 upto 0.05 percent can cause

A

increase in co2 fixation rates and beyond this level become damaging for longer periods

160
Q

at low light intensity which group responds to high co2 concentration c3,c4

A

none

161
Q

at high light intensity which group shows increase in rate of photosynthesis due to high co2 concentrations

A

both

162
Q

c4 plants show saturation at about

A

360

163
Q

c3 plants show saturation at

A

beyond 450

164
Q

c3 plants ability to respond to higher cimo2 concentration leads to

A

higher productivity due crops such as tomato and bell pepper

165
Q

dark reactions are controlled by

A

temperature

166
Q

light reactions are also temperature controlled but

A

are affected at a much lesser extent

167
Q

c4 plants respond to which temperature for higher rate of photosynthesis

A

higher temperature

168
Q
A
169
Q

c3 plants show higher rate of photosynthesis in temperature optimum

A

low temperature

170
Q

effect of water as a factor is more

A

through its effect on plant rather than directly on photosynthesis

171
Q

effect of water as a factor on plant

A

water stress causes stomata to close, reducing co2 availability, makes leaves wilt, reducing surface area of leaves and reducing metabolic rate

172
Q
A

botany (7 decks)

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