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Photosynthesis Flashcards

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1
Q

Photosynthesis is a _____ process.

A

Physico-chemical process

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2
Q

Photosynthesis is a physics-chemical process by which they use light energy to drive the synthesis of -

A

Organic compounds

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3
Q

Which simple experiment proves that photosynthesis occurs only in the green parts of leaves in the presence of light -

A

To look for starch formation in 2 leaves -variegated leaf or leaf that was partially covered with black paper

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4
Q

Which exp proves that CO2 was req for photosynthesis ?

A

A part of leaf is enclosed Ina test tube containing some KOH soaked cotton (which absorbs CO2 ) . On testing for the presence of starch , only the exposed part tested positive .

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5
Q

______in the year _____ revealed the essential role of air in the growth of green plants .

A

Joseph priestly

1770

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6
Q

_____ discovered O2 in the year __.

A

Joseph priestly

1774

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7
Q

Joseph priestly in the year 1770 revealed -

A

Essential role of air in the growth of green plants .

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8
Q

_____observed that a candle burning in a closed jar , soon gets extinguished .

A

Priestly

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9
Q

What was Joseph priestly’s hypothesis ?

A

Plants restore to air whatever breathing animals and burning candles remove .

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10
Q

Using a similar setup as the one used by PRIESTLY ,but by placing it once in the dark and once in the sunlight ,_____ showed that SUNLIGHT IS ESSENTIAL TO THE PLANT PROCESS (that purified the air )

A

Jan ingenhouz

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11
Q

______ in an elegant experiment with an ______ plant showed that in bright sunlight , small bubbles were formed around the green parts while in the dark they did not .

A

Ingenhouz

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12
Q

Who showed that it is ONLY THE GREEN PARTS OF THE PLANTS THAT COULD RELEASE OXYGEN .

A

JAN INGENHOUZ

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13
Q

What did jan engenhouz show-

A

2 things
Sunlight is essential to photosynthesis.
Only green plant parts release oxygen

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14
Q

In jan ingenhouzs’s experiment with an aquatic plant , small bubbles formed around the green parts were of -

A

O2

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15
Q

In year ____ , ______ provided evidence for production of glucose when plants grow .

A

1854

Julius Von Sachs

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16
Q

Julius Von Sachs showed that glucose is mainly stored as ______.

A

Starch

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17
Q

______ showed that green substances (chlorophyll) are located special bodies (chloroplasts ).

A

Von Sachs

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18
Q

What did Julius Von Sachs prove -

A

He found that GREEN PARTS is where GLUCOSE IS MADE and that the GLUCOSE is usually stored as STARCH .

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19
Q

______ used a prism and split light into its spectral components and then illuminated a green algae , (CLADOPHORA ) placed in a suspension of aerobic bacteria

A

T.W.Engelmann

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20
Q

The bacteria used in Engelmann’s experiment were used to detect sites of _____

A

O2 EVOLUTION

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21
Q

_____observed that bacteria accumulated mainly in the region of blue and red light of the split spectrum .

A

TW Engelmann

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22
Q

Who described the first ACTION SPECTRUM of photosynthesis ?

A

Engelmann

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23
Q

_____spectra of photosynthesis resembles _____ roughly the ____spectra of ________ .

A

Action
Absorption
Chloro a and b

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24
Q

What were Engelmann’s experiments and what did he observe?

A

Using a prism ,he split light into its spectral components and then illuminated green algae,CLADOPHORA placed in a suspension of AEROBIC bacteria . The bacteria were used to detect sited of O2 evolution .
He observed that bacteria accumulated in the region of blue and red light.

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25
Q

Empirical foramula of cabs -

A

CH2O

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26
Q

A milestone contribution to the understanding of photosynthesis was that made by a _____, ________.

A

Microbiologist

Cornelius van Neil

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27
Q

______ based o his studies on green and purple bacteria , demonstrated that photosynthesis is a light -dependent rxn .

A

Cornelius van Neil

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28
Q

Cornelius van Neil worked on _______ and ____ bacteria and demonstrated ______.

A

Purple green

Photosynthesis is a light-dependent rxn

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29
Q

Van Neil showed that H2 from a suitable _____ reduces ______ to ____ .

A

Oxidisable compound
CO2
Carbs

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30
Q

Write the expression based on van neil’s studies -

A

2 H2A + CO2 ———> 2A +CH2O+ H2O

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31
Q

In green plants _____ is the H donor and is oxidised to O2 .

A

H2O

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32
Q

Some organisms do not release O2 during photosynthesis .T/F

A

T

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33
Q

_____ is the H-donor for purple and green sulphur bacteria and the oxidation product is _____ or _____ depending on the organism and not O2 .

A

H2S

S or SULPHATE

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34
Q

Who inferred that O2 evolved comes from water and not form CO2 .

A

Cornelius van Neil

This was later proved by RADIOISOTOPIC tech

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35
Q

_____was proved using radioisotopic tech .

A

O2 is evolved from H2O

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36
Q

What did CORNELIUS van Neil prove ?

A

Photosynthesis is a light -dependent rxn in which H from a suitable oxidisable compound reduces CO2 to carbohydrates

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37
Q

_____cells in the leaves have a large number of chloroplasts .

A

MESOPHYLL cells

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38
Q

How to CHLOROPLASTS align themselves to get optimum quantity of incident light ?

A

Along the walls of the mesophyll cells

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39
Q

Within the chloroplasts , there is a _____ system consisting of grana, stroma lamella , and matrix stroma .

A

Membranous

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40
Q

The membranous system in chloroplasts consists of -

A

Grana
STROMA lamella
STROMA matrixa

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41
Q

There is a clear division of labour within the ___

A

Chloroplast

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42
Q

The membrane system in chloroplast is responsible for -

A

2 things-
Trapping light energy
Synthesis of ATP and NADPH

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43
Q

In _____ (part of membrane system ) , ENZYMATIC reactions synthesise SUGAR which in turn forms _____.

A

STROMA

Starch

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44
Q

Rxns like trapping light energy and synthesis of NADPH and ATP are _____.

A

Light dependent

Photochemical rxns

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45
Q

Dark reactions are also called -

A

Carbon rxns

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46
Q

We can separate the leaf pigments of any green plant through -

A

Paper chromatography

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47
Q

A chromatographic separation of the leaf pigments shows that the colour that we see in leaves is not due a a single pigment but due to _____ pigments .

A

4

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48
Q

What are the 4 main pigments of leaf -

A 
Chloro a (bright or blue green )
Chloro b (yellow green )
Xanthophylls (yellow)
Carotenoids (yellow to yellow orange )
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49
Q

______ are substances that have an ability to absorb light , at SPECIFIC WAVELENGTHS .

A

Pigments

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50
Q

Wavelengths at which there is max absorption of ______ (blue and red regions ) also shows higher rate of ______.

A

Chloro a

Photosynthesis

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51
Q

______ is the chief pigment associated with photosynthesis .

A

Chloro a

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52
Q

There is a complete one to one overlap between the ______ spectrum of chloro a and the ______ spectrum of photosynthesis.

A

Absorption

Action

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53
Q

Most of the photosynthesis takes place in the ___ and _____ regions of the spectrum .

A

Blue

Red

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54
Q

Some photosynthesis also takes place at other wavelengths of the visible spectrum (apart from blue and red ) .T/F

A

T

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55
Q

What are accessory pigments ? Name -

A

Chloro b
Xanthophyll
Carotenoids
Other thylakoids pigments that absorb light and transfer the energy to chloro a

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56
Q

______ enable a wider range of incoming light to be utilised for photosynthesis .

A

Accessory pigments .

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57
Q

_____prevent chloro a from photo-oxidation.

A

Accessory pigments

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58
Q

Light rxn or photochemical have includes __ , ____ and ___ .

A

light absorption
Water splitting
O2 release
Formation of high edgy chemical intermediates -ATP NADPH

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59
Q

The _____ are organised into ___ discreet photochemical _______ within the PS1 and PS2 .(light rxn)

A

Pigments
2
Light harvesting complexes (LHC)

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60
Q

The photosystems are named int he sequence of their _____.

A

Discovery

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61
Q

The ___ are made up of hundreds of pigment molecules bound to proteins .

A

LHC

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62
Q

Associated pigments protect chloro a from ________.

A

Photo-oxidation

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63
Q

Each photo system has all the pigments ( except chloro a ) forming a light harvesting system also called ______

A

Antennae

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64
Q

The pigments of photosystems forming an antennae help to make photosynthesis more EFFICIENT by -

A

Absorbing diff wavelengths of light

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65
Q

Which pigment in photosystems does not form a LHS or antennae -

A

One molecule of chloro a

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66
Q

The single chloro a molecule forms the ______ .

A

Reaction centre

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67
Q

The _____ is diff in both photosystems .

A

Reaction centre

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68
Q

In PS1 ,the reaction centre chloro a has an ABSORPTION peak at ______ ,hence is called _____ , while in PS2 it has absorption maxima at _______ , an is called _____

A

700nm
P700
680
P680

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69
Q

In photosystem ____ , the rxn centre chloro a absorbs 680nm of ___ light causing electrons to become excited and jump into an orbit farther from the atomic nucleus .

A

2

Red

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70
Q

The electron from PS 2 are picked up by an electron acceptor which passes them to an _____ consisting of _______.

A

Electrons transport system

Cytochromes

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71
Q

The ,movement of electrons through an ETS consisting on cytochromes is ___ in terms of ___ or __scale .

A

Downhill
Oxidation -reduction
Redox potential

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72
Q

The electrons from PS2 re not used up as they pass through ETS but are passed onto -

A

Pigments of PS1

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73
Q

The electrons in the rxn centre of PS1 also get excited when they receive __ light of wavelength ___.when does this happen ?

A

Red
700nm
When electrons from PS2 enter PS1

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74
Q

The excited e- from PS1 are transferred to another acceptor molecule that has ____.

A

Greater redox potential

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75
Q

The excited e- from PS1 move _____ , this time to a molecule of ___

A

Downhill

Energy-rich NADP+

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76
Q

What do the electrons from PS1 finally do ?

A

Reduce NADP+ to NADPH and H+

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77
Q

The whole scheme of transfer of e- starting from PS2 ___ to the acceptor down the ETC to PS1 , excitation of e- , transfer to another acceptor and finally downhill to NADP+ reducing it to NADPH + H+ is called __

A

Uphill

Z-scheme

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78
Q

The e- transfer scheme is called Z-scheme due to its __.

A

Characteristic shape

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79
Q

The Z shape of the scheme is formed when all the carriers are placed in a sequence on a ____.

A

Redox potential scale

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80
Q

Electrons from PS2 are transported _____ to the acceptor (up/downhill)

A

Uphill

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81
Q

How does PS22 supply e- continuously ?

A

E- removed from PS2 are replaced by e- available due to splitting of water .

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82
Q

The splitting of water is associated with PS __

A

2

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83
Q

Water is split into _ ,__ and _.

A

2H+
[O]
e-

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84
Q

The e- needed to replace those removed from PS1 are provided by -

A

PS2

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85
Q

Water s[plitting complex is associated with ps2 which is located on the ____ side of membrane of _____.

A

Inner

Thylakoid

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86
Q

Equation of water splitting -

A

2 H2O———> 4H+ +O2 +4e-

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87
Q

If ps2 is located on the inner side of membrane of thylakoid , then where are the protons and O2 likely to be released ?

A

Lumen of thylakoid

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88
Q

Living organism have the capability of extracting energy from ___substances and store this in the form of ____.

A

Oxidisable

Bond energy

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89
Q

ATP carry energy in their ___

A

Chemical bonds

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90
Q

ATP is synthesised by cells (in _ and __ ) is named _____.

A

Mitochondria
Chloroplast
Phosphorylation

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91
Q

______ is the synthesis of ATP from ADP and inorganic phosphate in the presence of light .

A

Photophosphorylation

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92
Q

When the 2 PS work in a series , a process called ________ occurs.

A

Non-cyclic photo-phosphorylation

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93
Q

The 2 PSs are connected through an -

A

ETC

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94
Q

What is synthesised at the end of non-cyclic photophosphorylation ?

A

ATP and NADPH + H+

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95
Q

Photophosphorylation is the synthesis of _____, from ___ and ____in the presence of light .

A

ATP
ADP
Inorganic phosphate

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96
Q

When only ____ is functional , the e- is circulated within the photosystem and cyclic phosphorylation occurs .

A

PS1

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97
Q

Cyclic phosphorylation occurs in the ______ of chloroplast .

A

STROMA lamella

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98
Q

The _______ has both PS1 and PS2 , therefore non-cyclic phosphorylation occurs here .

A

Membrane or lamella of grana

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99
Q

The _____ lack PS2 , therefore cyclic-phosphorylation occurs here.

A

STROMA lamella membrane

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100
Q

The STROMA lamella membrane lacks _ and _____ .

A

Both PS2 and NADP reductase enzyme .

Cyclic phos. Occurs here

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101
Q

In cyclic phosphorylation the excited e- does not pass on to ___ but are cycled back to ____ through the ETC

A

NADP+

PS1

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102
Q

The end products of cyclic phosphorylation .

A

Only ATP

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103
Q

_____ phosphorylation occurs when ONLY LIGHT of wavelengths BEYOND 680nm are available for excitation .

A

Cyclic

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104
Q

Cyclic phos occurs when only light of wavelengths ______ are available for excitation .

A

Beyond 680nm

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105
Q

The ___ hypothesis has been put forward to explain the mechanism of ATP synthesis in the chloroplast .

A

Chemiosmotic

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106
Q

Like in _____ , in photosynthesis too , ATP synthesis is linked to development of a _____ across a membrane .

A

Respiration

Proton gradient

107
Q

What is the diff in ATP synthesis in respiration and photosynthesis ?

A

In photosynthesis , proton accumulation is inside the lumen (inside the membrane )
In respiration , protons accumulate in the intermembrane space of mito
When e- move through ETS .

108
Q

In photosynthesis , protons accumulation is on the ______ side of membrane .
While in respiration , protons accumulate in _______.

A

Inner (lumen )

Intermembrane space

109
Q

Why do. Protons or H+ions accumulate on the inner side of the membrane ?

A

Since splitting of water takes place on the inner side of the membrane , therefore H+ ions produced by splitting of water accumulate within the lumen of the thylakoid .

110
Q

As electrons move through the photosystems , protons are transported ______ the ____.

A

Across the membrane

111
Q

Primary acceptor of e- is located on the ______ side of membrane.

A

Towards the outer side

112
Q

The primary acceptor of e- transfers its e- not to a _____ but to a __.

A

e- carrier

H Carrier

113
Q

As e- move through the PSs , _____ are transported across the membrane . Why ?

A

Protons
Becoz prim acceptor of e-(plastoquinone ) transfers its e- to a H carrier . This H carrier removes a proton from the stroma while transporting an e-.

114
Q

______ removes a proton from the stroma while transporting an e-.

A

H carrier

115
Q

Name the prim acceptor of e- (from PS2)

A

Plastoquinone

116
Q

Name the H carrier which removes a proton from the stroma while transferring an e-

A

Cytochrome B6f

117
Q

The H carrier passes on its e- to the e- carrier located on the _____ side of the membrane of thylakoid .

A

Inner

118
Q

What happens when the H carrier passes on its e- to the e- carrier on the inner side of the membrane ?

A

The proton (which H carrier was carrying after removing it from the stroma {outside thylakoid} )is released into the inner side or LUMEN of the membrane of thylakoid .

119
Q

The NADP REDUCTASE enzyme is located on the ______ side of the membrane .

A

STROMA (outer)

120
Q

Along with the e- that come from acceptor e- of PS1 , ___ are necessary for the reduction of NADPH + H+

A

PROTONS

121
Q

Protons are necessary for the reduction of _____ . Where do they come from ?

A

NADP to NADPH and H+

These protons are removed from the stroma .

122
Q

Within the chloroplast , protons in the ______ dec in number , while in the _____ ,ther is accumulation of e- .

A

STROMA

Lumen

123
Q

State 3 ways in which protons accumulate in the lumen of thylakoid -

A

1) protons or H+ released due to splitting of water ( in PS2 which is locate on the inner side of membrane )
2) prim acceptor of e- (outer side ) transfers e- to a H+ carrier ,therefore the H+ carrier removes a proton from the stroma , while transporting this e- . When it passes its e- to the e-carrier on the inner side , it releases the proton into the lumen .
3) protons are necessary for the reduction of NADP , so they are removed from the stroma .

124
Q

Name the e- carrier to which H+ carrier transfers its e- ?

A

Plastocyanin

125
Q

Due to the proton gradient across the thylakoid membrane , pH decreases in the _____ .

A

Lumen

Due to inc in H+

126
Q

The breakdown of proton gradient leads to the _______.

A

Synthesis of ATP

127
Q

The proton gradient is broken down due to the movement of protons across the membrane to the STROMA through the _____ of the _____ of the _______ .

A

Transmembrane channel
CFo
ATP synthase

128
Q

The ATP synthase enzyme consists of 2 parts :

A

CFo

CF1

129
Q

The _____ part of ATP synthase forms the transmembrane channel .

A

CFo

130
Q

The CFo part f ATP synthase carriers out ________ of protons across the membrane .

A

Facilitated diffusion

131
Q

The ____part of ATP synthase is embedded in the thylakoid membrane .

A

CFo

132
Q

The ____ portion of ATP synthase protrudes on the OUTER SURFACE OF THYLAKOID MEMBRANE on the side that faces STROMA .

A

CF1

133
Q

The breakdown of the gradient provides enough energy to cause a ________ change in the ____ .

A

Conformational change

CF 1

134
Q

WHAT makes the enzyme ATP synthase synthesise several molecules of energy-packed ATP ?

A

Breakdown of proton gradient which causes conformational change in the CF1 parts of ATP synthase

135
Q

Chemiosmosis requires a ___,_____, _____ and _______.

A

Membrane
Proton pump
Proton gradient
ATP synthase

136
Q

Energy is used to pump ____ across a membrane , to create a gradient or a high conc of ____ within the ______ .

A

Protons
Protons
thylakoid lumen

137
Q

______ has a channel that allows DIFFUSION of protons back across the membrane .

A

ATP synthase

This process releases enough energy to activate atp synthase enzyme for the formation of atp

138
Q

Along with the NADPH , ATP is used immediately in the biosynthetic phase .T/F

A

T

139
Q

______ is responsible for fixing CO2 and synthesis of sugars .

A

Biosynthetic phase

140
Q

Products of light rxn -

A

ATP
NADPH
O2

141
Q

Immediately after light becomes unavailable , the _____ continues for some time and then _____ .

A

Biosynthetic phase

Stops

142
Q

If light is made available ,_____ starts again .

A

Biosynthetic (dark)

Also light

143
Q

Just after world war 2 , among the several efforts to put RADIOISOTOPES to use ,the work of ____ is exemplary .

A

Melvin Calvin

144
Q

The use of _____ by Melvin Calvin in _____ studies led to the discovery of _____.

A

Radioactive C14
Algal photosynthesis
First CO2 fixation product - 3 C organic acid

145
Q

Biosynthetic pathway is also called ______ and why ?

A

Calvin cycle

He contributed to working out the complete biosynthetic pathway .

146
Q

The first CO2 fixation product was __________

A

3-phosphoglyceric acid (PGA)

3-C organic acid

147
Q

CO2 assimilation during photosynthesis is said to be of _____ main types .

A

2

148
Q

What is the basis of division of CO2 assimilation into 2 main types ?

A

1st - those plants that produce C3 acid (PGA )as the first product o CO2 fixation - C 3 pathway
2nd- those plants that have C4 acid (OAA) as the first product -C4 pathway

149
Q

How many C atoms would a molecule have which after accepting CO2 would have 3 C PGA ?

A

5

150
Q

The primary acceptor (fixer) of CO2 is a ______ sugar called ____.

A

5 C ketone sugar

RuBP ribulose bisphosphate

151
Q

Calvin showed that the pathway operated in a _____ manner .

A

Cyclic

152
Q

The CALVIN PATHWAY occurs in _____

A

All photosynthetic plants

It doesn’t matter whether they have C3 , C4 or any other pathways

153
Q

Calvin cycle can be described under ____ stages .name —

A

3
Carboxylation
Reduction
Regeneration

154
Q

_____ is the fixation of CO2 into a stable organic intermediate .

A

Carboxylation

155
Q

______ is the most crucial step of the Calvin cycle .

A

Carboxylation

156
Q

In Calvin cycle , _____ is utilised for the carboxylation of ___

A

CO2

RuBP

157
Q

Carboxylation is catalysed by _____ which results in the formation of ___

A

Enzyme RuBP carboxylase

2 molecules of 3-PGA

158
Q

RuBP carboxylase also has ____ activity so its correct name is -

A

Oxygenase

RuBisCO

159
Q

Series of reaction that lead to the formation of GLUCOSE ( in Calvin cycle ) are-

A

Reduction

160
Q

Reduction step involves utilisation of _____for ____and_____for_____ per CO2 fixed .

A

2 molecules of ATP
Phosphorylation
2 molecules of NADPH
Reduction

161
Q

The fixation of _____molecules of CO2 and _____ turns of the cycle are req for the formation of _____molecules of GLUCOSE from Calvin pathway .

A

6
6
1

162
Q

_____ of the c2 acceptor molecule Rubpi crucial if the cycle is to continue uninterrupted .

A

Regeneration

163
Q

Which step involves utilisation of 2 molecules of ATP and NADPH (per turn )

A

Reduction

3PGA ——reduction———>triose phosphate

164
Q

The regeneration steps require _____ for ____ to form RuBP (again )

A

1 ATP

Phosphorylation

165
Q

For every CO2 molecule entering the Calvin cycle ____ ATP and ___ NADPH are req.

A

3 molecules

2 molecules

166
Q

To meet the difference in number of ATP and NADPH used in the DARK RXN that the ___takes place .

A

Cyclic phosphorylation

Only ATP

167
Q

What comes out of Calvin cycle ?

A

1 glucose
18 ADP
12 NADP

168
Q

Plants that are adapted to ______ regions have C4 pathway .

A

Dry tropical regions

169
Q

C4 plants use _____ as the main photosynthetic pathway .

A

C3 pathway

Though C4 acid is the first fixation product

170
Q

C4 plants have a special _____.

A

Leaf anatomy

171
Q

Special features of C4 plants -

A 
5
Special leaf anatomy
Tolerate high temp 
Show response to high light intensities 
Lack photorespiration
have Greater productivity of biomass
172
Q

C4 plants respond to ____ light intensities .

A

High

173
Q

C3 and C4 have same type of MESOPHYLL .T/F ?

A

F

174
Q

The particularly large cells around the ______of the C4 plants are called ____.

A

Vascular bundles

Bundle sheath cells

175
Q

C4 pants have large cells around vascular bundles called bundle sheath cells .this anatomy is called -

A

Kranz anatomy

176
Q

Kranz means __ and is a reflection of the ______ of cells .

A

Wreath

Arrangement

177
Q

The ___may form SEVERAL LAYERS around the vascular bundles .

A

Bundle sheath cells

178
Q

Name 2 C4 plants .

A

Maize

Sorghum

179
Q

Bundle sheath cells are characterised by ____number of CHLOROPLASTS , ____walls IMPERVIOUS to____ and __ intercellular spaces .

A

Large
Thick
Gaseous exchange
No

180
Q

Presence of bundle sheath cells is a characteristic of -

A

C4 plants

181
Q

C4 pathway has been named __ and is a __ pathway .

A

Hatch and slack

Cyclic

182
Q

Describe kranz anatomy -

A

Bundle sheath cells form several layers around the vascular bundles and have large no of chloroplasts ,thick walls impervious to gaseous exchange and no intercellular spaces

183
Q

The primary CO2 acceptor in C4 -

A

3 C molecule -PEP phosphoenol pyruvate

In C3 - 5 C RuBP

184
Q

The primary CO2 acceptor in C4 (PEP) is found in ____ cells .

A

MESOPHYLL

185
Q

The enzyme req for prim CO2 fixation is C4 -

A

PEPcase

186
Q

The mesophyll cells in C4 plants lack -

A 
RuBisCO enzyme 
(Have PEPcase)
187
Q

The C4 acid ____ is formed in ______ cells .

A

OAA
MESOPHYLL
(PEP ——PEPcase——>OAA)

188
Q

The OAA forms other ____ compounds like. ___and _____.

A

4C
Malic acid
Aspartic acid

189
Q

OAA forms aspartic acid and malic acid in the __cells itself which are then transported to the __cells .

A

MESOPHYLL

Bundle sheath cells

190
Q

In the BUNDLE SHEATH CELLS ,the C4 acids (malic or aspartic) are broken down to release ____and _____.

A

CO2

3C molecule

191
Q

The 3C compound is transported back to the _____ where it is converted to _____again ,thus completing the cycle .

A

MESOPHYLL

PEP

192
Q

The __released in the BUNDLE sheath cells enters the C3 or Calvin pathway .

A

CO2

193
Q

C3 (Calvin) cycle occurs in the __cells in C3 pants while in C4 plants it occurs in _cells

A

MESOPHYLL

Bundle sheath cells

194
Q

In _____cells the C4 acids are broken down to release CO2 and 3 C compound .

A

Bundle sheath cells

In mesophyll cells -C4 acids are formed

195
Q

In bundle sheath cells , the C4 acids are converted to CO2 and C3 acid through _____.

A

Decarboxylation

196
Q

In C4 plants , regeneration occurs in ____cells .

A

MESOPHYLL cells

Where , C3 acid——-regeneration——>PEP

197
Q

In C4 plants , decarboxylation occurs in ___Cells .

A

Bundle sheath cells

198
Q

In C4 , bundle sheath cells are rich in ______.

A

RuBisCO

Lack PEPcase

199
Q

Calvin pathway in C4 plants takes place in _____cells .

A

Bundle sheath cells

200
Q

Calvin cycle occurs in all mesophyll cells of C3 pant .T/F

A

T

201
Q

Give the equation of ist CO2 fixation step in C3 .

A

RuBP + CO2 —RuBisCO—>2* 3PGA

202
Q

_____ is the most abundant enzyme in the WORLD .

A

RuBisCO

203
Q

RuBisCO is characterised by the fact that its _____can bind with both _and__.

A

Active site
CO2
O2

204
Q

Rubisco has a much greater affinity for ___when CO2: O2 ratio is nearly equal .

A

CO2

205
Q

The binding in rubisco is ______.

A

Competitive

206
Q

It is the ___of CO2 and o2 that determines which will bind to the enzyme .

A

Relative conc

207
Q

In C3 plants , some ___des bind with rubisco ,hence ___is DECREASED .

A

O2

CO2 fixation

208
Q

When instead of CO2 ,o2 binds with with rubisco (shows RuBP oxygenase activity now)then RuBP binds with o2 to form _____and _____.

A

Phosphoglycerate

Phosphoglycolate (2C)

209
Q

in photorespiration ,there is neither synthesis of __ nor __.

A

Sugars

ATP

210
Q

Photorespiration results in the release of ____ with the ___ .

A

CO2

Utilisation of atp

211
Q

In _____ ,there is no synthesis of atp or nadph .

A

Photorespiration

212
Q

What is photorespiration .

A

When instead of CO2 , o2 combines with rubisco (its carboxylation activity is dec and oxygenase part functions ) . Here RuBP instead of being converted to PGA binds with o2 to form 1 molecule of PHOSPHOGLYCERATE or PHOSPHOGLYCOLATE (2C)

213
Q

In C4 plants photorespiration does not occur .why ?

A

Becoz they have a mechanism that inc. the conc of CO2 at the enzyme site .

214
Q

In C4 plants the mechanism that inc the conc of CO2 occurs when : C4 acid from the __cells is broken down in the __ cells to release CO2.

A

MESOPHYLL

Bundle sheath cells

215
Q

When C4 acid is broken down in the bundle sheath to release CO2 , it results in increasing the ____of CO2 .

A

Intracellular conc

216
Q

Increasing intracellular conc of CO2 ensures that -

A

Rubisco functions as carboxylase minimising oxygenase activity

217
Q

Tolerance to high temp is shown by __ plants .

A

C4

218
Q

The plant factors that affect photosynthesis -

A

Number , size , age and orientation of :: leaves ,mesophyll cells and chloroplasts
Internal CO2 conc
Amount of chlorophyll

219
Q

The plant or internal factors are dependent on the ______ and the _____ of the plant .

A

Genetic predisposition

Growth

220
Q

The external factors affecting photosynthesis are :

A

Availability of sunlight , temp , CO2 conc and water

221
Q

Though several factors interact and simultaneously affect photosynthesis , only one factor is the major cause or is the one that ____ the rate .

A

Limits

222
Q

At any point ,the rate will be determined by the factor available at _____ levels .

A

Sub-optimal

223
Q

When several factors affect any chemical. Process , _____ law comes into effect .

A

Blackman’s law of limiting factors

224
Q

According to Blackman’s law of limiting factors , if a chemical process is affected by more than one factor ,then its rate will be determined by the factor which is NEAREST to its ______.

A

Minimal value

225
Q

The factor nearest to its minimal value affects photosynthesis _____directly /indirectly if its quantity is changed .

A

Directly

226
Q

Blackman’s law of limiting factors as given in the year -

A

1905

227
Q

Despite the presence of a green leaf and optimal light and CO2 conditions , the plant ____ photosynthesise if the temp is ______ .

A

may not

Very low

228
Q

We need to distinguish between light _____, light ____and the duration of ______.

A

Quality
Intensity
Exposure to light

229
Q

There is a ___relationship between incident light and CO2 fixation rates at ___light intensities .

A

Linear

Low

230
Q

There is a linear relationship between _____and ___ at ___

A

Incident light
CO2 fixation rates
Low light intensities

231
Q

At _____light INTENSITIES , gradually the rate (CO2 fixation )does not show further increase .

A

High

232
Q

Why at high light intensities ,the rate ( of CO2 fixation) does not show further if ?

A

As other factors become limiting

233
Q

Light saturation occurs at __% of the full sunlight .

A

10%

234
Q

For what kind of plants LIGHT is a limiting factor ?

A

Plants in shade or in dense forests 🌳

235
Q

Except for plants in shade or in dense forests ,_____is rarely a limiting factor .

A

Light

236
Q

Increase in INCIDENT LIGHT beyond a point causes the ______ and a dec in photosynthesis .

A

Breakdown of chlorophyll

237
Q

______is the major limiting factor for photosynthesis .

A

CO2

238
Q

The conc of CO2 is ____ in the atm ,between ____and____%.

A

Very low

0.03 -0.04%

239
Q

Increase in conc of CO2 upto ___% can cause an INCREASE IN CO2 FIXATION RATES .

A

0.05%

240
Q

Beyond which level can CO2 become damaging over long periods ?

A

0.05%

241
Q

The C3 and C4 plants respond diff to ___conc .

A

CO2

242
Q

At low light intensities , ____group (C3 /C4) responds to high CO2 conditions .

A

Neither

243
Q

At high light intensities _ C3 /C4 show inc in the rates of photosynthesis .

A

Both c3 and C4

244
Q

C4 plants show saturation at about _____(co2 conc )

A

360 uIL- (co2 conc)

245
Q

C3 plants respond to _____co2 conc and saturation is seen only beyond __

A

Increased

450 uIL-

246
Q

___availability of co2 levels is limiting to the ____plants .

A

Current

C3

247
Q

At _____ , light intensities , both c3 and C4 show inc in the rates of photosynthesis .

A

High

At low intensity ,neither respond

248
Q

Which fact has been used for some GREEN HOUSE crops ?

A

The fact that c3 plants respond to HIGHER CO2 CONC by showing increased rates of photosynthesis leading to higher productivity .

249
Q

Name some greenhouse crops (which grow in higher co2 conc)

A

Tomatoes 🍅
Bell pepper
(These are c3 plants )

250
Q

_____plants are allowed to grow in CO2 enriched atm that leads to higher yields .

A

C3

Tomatoes 🍅 and bell pepper

251
Q

The dark rxn being __Are ____controlled .

A

Enzymatic

Temp

252
Q

____ rxns are also TEMP sensitive but they are affected to a much ____ extent .

A

Light

Lesser

253
Q

The ____plants respond to higher temp and show higher rates of photosynthesis .

A

C4

254
Q

_____plants have a much LOWER TEMP OPTIMUM .

A

C3

Respond to low temp properly ,unlike C4

255
Q

The TEMP OPTIMUM for photosynthesis of diff plants also depends on the ___

A

Habitat that they are adapted to

256
Q

____plants have a HIGHER TEMP OPTIMUM than the plants adapted to _____climates . (Tropical /temperate)

A

Tropical

Temperate

257
Q

____rxns are temperature controlled.

A

Dark

Becoz they are enzymatic

258
Q

Even though ____is one of the reactants in the light rxn , its effect as a factor is more through its effect on the plant , rather Han directly on photosynthesis.

A

Water

259
Q

Water stress causes ____ hence reducing _____.

A

Stomata to close

The co2 availability

260
Q

Water stress also makes leaves ___ ,hence reducing the _____ of leaves and their _____ as well .

A

Wilt
SA
Metabolic activity

261
Q

_____causes the stomata to close and makes leaves wilt .

A

Water stress

262
Q

What happens when a leaf wilts .

A

Leaf 🍃 SA is reduced and therefore their metabolic activity

263
Q

Prim Electron acceptor of PS 1 -

A

An Fe-S protein

Biology 2 (10 decks)

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