Physiology of Plants MCQs Part V

1) Our present day view regarding photosynthesis is that it
a) Creates useful energy
b) Converts light energy into chemical energy only
c) Reverses the action of respiration

2) The percentage of light energy fixed in photosynthesis is generally around
a) 50
b) 3
c) 10
d) 1

3) The percentage of light energy utilized for photosynthesis by higher plants is
a) 1 – 2
b) 10
c) 50
d) 100

4) Photosynthesis is the conversion of light energy into chemical energy within a plant. This was first stated by
a) Willstatter and Stoll
b) Mayor and Anderson
c) Benson and Calvin
d) Robert Mayer

5) The process of photosynthesis takes place in
a) The cells of leaves
b) The chloroplasts
c) The leaves
d) The entire plant

6) Discovery of the ‘Emerson effect’ has shown the existence of

a) the light and dark reactions in photosynthesis
b) Two distinct photochemical reactions
c) Photorespiration
d) Photophosphorylation

7) The Emerson effect means an increase in photosynthetic yield due to
a) the prolonged exposure of the plant to white light
b) the combined effect of yellow and green light on plants
c) the combined effect of supplementary red light with far-red light
d) the prolonged effect of UV rays

8) The oxygen evolved in photosynthesis comes from water. This was confirmed
by using

d) Chlorine ions

9) The path of
in the dark reaction of photosynthesis was successfully traced by the use of which of the following?

c) 32p
d) X-rays

10) Who received the Nobel prize for working out the early carbon pathway
of photosynthesis?

a) Calvin
b) Krebs
c) Khorana
d) Watson

11) Which of the following techniques has been most useful for investigating
the Calvin Cycle?

a) Flash light experiment
b) Radioactive isotope technique
c) X-ray technique
d) None of these

12) The alga used by Calvin and his co-workers in their experiments on photosynthesis

a) Chlamydomonas
b) Chlorella
c) Chara
d) Euglena

13) The isotope of carbon used extensively for studies in photosynthesis


14) Which pigment is absent in chloroplasts?
a) Xanthophyll
b) Anthocyanin
c) Chlorophyll-a
d) Carotene

15) Photosynthetic pigments in a chloroplast are embedded in the membrane
of the

a) Thylakoids
b) Photoglobin
c) Matrix
d) Envelope of chloroplast

16) The unit of photosynthesis is the
a) Quantasome
b) Angstrom
c) Geotropism
d) None of these

17) Quantasomes contain
a) 200 chlorophyll molecules
b) 230 chlorophyll molecules
c) 250 chlorophyll molecules
d) 300 chlorophyll molecules

18) Starch-containing plastids are called
a) Amyloplasts
b) Leucoplasts
c) Chloroplasts
d) Chromoplasts

19) The chemical formula for chlorophyll a is

20) The correct molecular formula for chlorophyll B is

21) The main difference between chlorophyll a and chlorophyll b is CORRECT IMAGE
a) chlorophyll a is a linear compound while chlorophyll b is a branched one
b) chlorophyll a has no magnesium ion in the centre
d) All the above

22) For chlorophyll formation in plants, the elements needed are
a) Sodium and copper
b) Calcium and potassium
c) Iron and magnesium
d) Iron and calcium

23) Chlorophyll absorbs
a) Red light only
b) Blue light only
c) Blue as well as red light
d) Green light

24) Which colour of light shows a maximum absorption peak with chlorophyll a ?
a) Yellow
b) Red
c) Blue
d) Green

25) Etiolated plants are formed due to lack of
a) Light
b) Hg
c) Fe
d) Mg

26) In a chlorophyll molecule, the magnesium is situated in the
a) Centre of the porphyrin ring
b) Corners of the porphyrin molecule
c) Phytol chamber
d) Isocyclic ring

27) Which metal is present in chlorophyll?
a) Mn
b) Mo
c) Mg
d) S

28) Chlorophyll is present
a) In the grana of chloroplasts
b) On the surface of chloroplasts
c) Dispersed throughout the chloroplasts
d) In the stroma of chloroplasts

29) In the process of photosynthesis, chlorophyll functions as
a) A raw material
b) A hydrogen acceptor
c) An end-product
d) An energy converter

30) The role of chlorophyll in photosynthesis is
b) Absorption of light
c) Absorption of light and photochemical decomposition of water
d) Absorption of water

31) The chlorophyll a molecule at its carbon atom-3 of the pyrrole ring II has one of the following:
a) Carboxyl group
b) Magnesium
c) Methyl group
d) Aldehyde group

32) One of the following will be reflected most, when a beam of white light
is directed at a solution of chlorophyll:

a) White
b) Green
c) Yellow
d) Blue

33) The thylakoids of the grana possess the
a) Enzymes for the Calvin cycle
b) Enzymes for photophosphorylation
c) Enzymes for the C-3 pathway
d) Enzymes for the C-4 pathway

34) The green wavelength of light is reflected by
a) Phycocyanin
b) Carotenoids
c) Chlorophylls
d) Phycoerythrins

35) A chloroplast contains the maximum quantity of
a) Pyruvic carboxylase
b) Hexokinase
c) RUDP (RuBP) carboxylase
d) None of the above

36) Chlorophyll a is found in
a) All oxygen releasing photosynthetic forms
b) All plants except fungi
c) All higher plants that photosynthesize
d) All photosynthetic prokaryotes and eukaryotes

37) In Angiosperms, the synthesis of chlorophyll occurs in the presence of
a) Phytochrome
b) Light
c) Cytochrome
d) None of the above

38) Leaves appear green because they
a) Reflect green light
b) Absorb green light
c) Both reflect and absorb green light
d) None of the above

39) Which wavelength of light is needed for photosynthesis in bacteria?
a) Red
b) Infrared
c) Ultra violet
d) Blue

40) The chlorophylls absorb visible light in the region of the following
wave lengths:

a) 400 nm to 500 nm only
b) 600 nm to 800 nm only
c) 400 nm to 500 nm and 600 nm to 700 nm
d) 300 nm to 400 nm only

41) The photochemical reaction or the light reaction of photosynthesis is

42) Hill’s reaction results in the production of
c) Phosphoglyceric acid
d) Glucose

43) The full form of NAD is
a) Nicotinamide adenine diphosphate
b) Nicotine adenosine diphosphate
c) Nicotinamide adenine dinucleotide
d) Nicotinamide adenosine dinucleotide

44) The first step in photosynthesis is the
a) Joining of 2 3-carbon atoms to form glucose
b) Formation of ATP
c) Ionization of water
d) Excitement of an electron of chlorophyll by a photon of light

45) When a cell transfers light energy into chemical energy which
of the following reactions would take place?

a) ATP – iP = ADP
b) ADP + iP = ATP
c) GDP + P = GTP
d) AMP + iP = ADP

46) The first phenomenon in photosynthesis is
a) Excitation of plant
b) Excitation of an electron in the chlorophyll molecule
c) Diffusion of oxygen into the stomata
d) Photolysis of water molecule

47) The source of liberated in photosynthesis is
a) the photosynthetic enzymes
b) the carbohydrate present in the leaf
c) Water
d) Carbon dioxide

48) Light reactions take place in the
a) Stroma
b) Grana
c) Cytoplasm
d) Endoplasmic reticulum

49) In photosynthesis, the light reaction occurs in the
a) Thylakoids
b) Fret channel
c) Stroma
d) All of the above

50) Radiant energy is stored in the form of chemical energy

a) ATP
b) Stored food
c) RNA
d) DNA

51) Which one of the following pigments acts as a reaction centre
during photosynthesis?

b) Cytochrome
c) Carotene
d) Phytochrome

52) During the light reaction the following molecules are formed:
a) ATP
d) None of these

53) The specific function of light energy in the process of
photosynthesis is to

a) Reduce carbon dioxide
b) Synthesize glucose
c) Activate chlorophyll
d) Split water

54) During the photochemical reactions of photosynthesisCORRECT IMAGE

55) The thylakoids of the grana possess the
a) Enzymes of the Krebs cycle
b) Enzymes of the C-3 pathway
c) Enzymes of the C-4 pathway
d) Enzymes for photophosphorylation

56) ATP formation during photosynthesis is known as
a) Oxidative phosphorylation
b) Phosphorylation
c) Photophosphorylation
d) None of the above

57) The trapping centre of light energy in photosystem I is
a) P-660
b) P-680
c) P-700
d) P-720

58) The electrons excited from the pigment system-II pass directly to
a) Ferridoxin
b) Plastocyanin
c) Plastoquinone
d) Carotenoids

59) The role of PS II in photosynthesis is
a) To cause photolysis of water
b) To release energy

60) Photolysis of water takes place in
a) the Calvin cycle
b) Glycolysis
c) the light reaction of photosynthesis
d) the dark reaction

61) Photolysis of water is associated with
a) PS I
b) PS II
c) Cytochrome b
d) Quinone

62) Photosystem II occurs
a) In the stroma
b) In the grana
c) On the surface of mitochondria
d) On the cytochrome

63) In blue-green algae, photosystem II contains an important
pigment concerned with photolysis of water. It is called

b) Chlorophyll b
c) Cytochrome
d) Phycocyanin

64) The role of PS I in photosynthesis is to
a) Release oxygen from water
b) Cause photolysis of water
c) Synthesize ADP
d) Produce NADPH2

65) Hill’s reaction takes place in the
a) Dark
b) Light
c) Both dark and light
d) Any time

66) The first step in the process of photosynthesis is
a) Absorption of light by chlorophyll of both PS I and PS II
b) Absorption of light by chlorophyll of PS I only
c) Absorption of light by chlorophyll of PS II only

67) The substance which acts as an electron donor in the photosynthetic
process is

b) Sugar
c) Water
d) Enzyme

68) Cyclic photophosphorylation involves
a) Pigment system I
b) Pigment system II
c) Both pigment system I and II
d) None of the above

69) Cyclic photophosphorylation releases
c) ATP only

70) Which is the evidence to show that oxygen released in photosynthesis comes from water?CORRECT IMAGE
d) All the above

71) Which element helps in the transport of electrons
from water in photosynthesis?

a) Na and K
b) Mo
c) B
d) Mn and CI

72) The concept of two photosystems participating
in the light reaction of photosynthesis was given

a) D.I. Arnon
b) F.F. Blackman
c) R. Hill
d) Robert Emerson

73) The red drop phenomenon is due to the disruption of the photochemical activity of
a) PS I
b) PS I & II both
c) PS II
d) Carotenoids

74) In bacterial photosynthesis, the hydrogen donor


75) Bacterial photosynthesis is different from
that of higher plants as

a) Energy is not fixed
b) Light is not required
c) Oxygen is not released
d) A host organism is required

76) In the pigment system I (PS I), energy is captured

a) Chlorophyll a + anthocyanins
b) Chlorophyll a + vitamins
c) Chlorophyll a + phycobilins
d) Chlorophyll a + carotenoids

77) In pigment II (PS II) the energy is captured

a) Chlorophyll + carotenes + xanthophyll
b) Chlorophyll a + Chlorophyll b + phycobilins
c) Chlorophyll b + carotenes + xanthophylls
d) Carotenes + xanthophylls + phycobilins

78) The sequence of electron transfer during cyclic
photophosphorylation isCORRECT IMAGE


79) During the ionisation of water in photosynthesis, the is captured by —
a) Cytochrome
b) ChlorophyII
d) Oxygen

80) Which of the following photosynthetic bacteria
have both PS I and PS II?

a) Green sulphur bacteria
b) Purple sulphur bacteria
c) Purple non-sulphur bacteria
d) Cyanobacteria

81) In photosynthesis, dark reactions occur in the
a) Granal lamellae
b) Stroma
c) Stromal lamellae
d) Thylakoids

82) The assimilatory power in photosynthesis

a) ATP

83) During the dark reactions of photosynthesisCORRECTIMAGE
a) 6C sugar is broken down into 3C sugar
b) Water is split
d) Chlorophyll is activated

84) The Calvin cycle occurs in the
a) Cytoplasm
b) Chloroplast
c) Glyoxysomes
d) Mitochondria

85) Which of the following occurs during the dark
phase of photosynthesis?

a) Hydrogen is released
b) ATP is produced
c) Molecular oxygen is released
d) PGA is synthesized

86) The Calvin cycle
a) is dependent on light
b) is not dependent on light
c) occurs in the light
d) occurs in the dark

87) The carbon dioxide acceptor in plants is
a) Phosphoglyceric acid (PGA)
b) Ribulose monophosphate (RMP)
c) Ribulose 1, 5 diphosphate (RUDP)
d) Phosphoenol pyruvate (PEP)

88) Which of the following enzymes is used for
carboxylation of RUDP?

a) Phosphopentokinase
b) Peroxidase
c) Ribulose biphosphate carboxylase
d) Carboxymutase

89) The first product of photosynthesis in the pathway is
a) 3-phosphoglyceric acid
b) Dihydroxyacetone phosphate
c) Fructose 1, 6-disphosphate
d) Ribulose 1, 5-bisphosphate

90) The enzyme ribulose bisphosphate carboxylase
catalyses the reaction betweenCORRECT IMAGE

b) Oxaloacetic acid and acetyl CoA
c) PGA and dihydroxy acetone phosphate
d) Ribulose diphosphate and phosphoglyceraldehyde

91) The first stable compound in the cycle is
a) Glucose
b) Phosphoglyceraldehyde (PGAL)
c) Phosphoglyceric acid (PGA)
d) Fructose-1-6 diphosphate

92) During photosynthesis, when PGA
is changed into phosphoglyceraldehyde,
which of the following reactions occurs?

a) Oxidation
b) Hydrolysis
c) Electrolysis
d) Reduction

93) In plants, the Calvin cycle CORRECT IMAGE
a) Occurs in the stroma of the bundle sheath chloroplasts
b) Occurs in the mesophyll chloroplasts
c) Occurs in the grana of the bundle sheath chloroplasts

94) The first visible product of photosynthesis is
a) Starch
b) Glucose
c) Fructose
d) Sucrose

95) For photosynthesis (i.e. for
the synthesis of organic matter),
the green plants need CORRECT IMAGE

a) Light
b) Chlorophyll
d) All of these

96) The level of carbon dioxide in the atmosphere remains relatively
constant because CORRECT IMAGE


97) Carbon dioxide is necessary for photosynthesis; the chemical used to remove this gas most effectively from entering a control apparatus is
a) Calcium oxide
b) Distilled water
c) Sodium carbonate
d) Potassium hydroxide solution

98) Moll’s experiment showsCORRECT IMAGE
b) that chlorophyll is essential for photosynthesis
c) Unequal transpiration from the two surfaces of a leaflet
d) the relation between transpiration and absorption

99) Which of the following proves that is essential for photosynthesis?

100) Light energy is changed into chemical energy during the process of
a) Transpiration
b) Photosynthesis
c) Digestion
d) Respiration


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