Cell & Cell Division Part V

1) One of the following is not true of facilitated diffusion:
a) It requires energy input
b) It is a passive process
c) Solutes are moved by a change in shape of the carrier protein
d) The solutes are moved by a change in shape in either direction

2) One of the following methods for transporting substances across
a membrane does not involve a change in extrinsic and intrinsic
proteins:

a) Na-K pump
b) Active transport
c) Simple diffusion
d) Facilitated diffusion

3) The cellular secretion of macromolecules by fusing a transport vesicle
to the plasma membrane is

a) pinocytosis
b) phagocytosis
c) endocytosis
d) exocytosis

4) Cell eating is called
a) pinocytosis
b) phagocytosis
c) osmosis
d) diffusion

5) Ion carriers are located in the
a) cell wall
b) cell membrane
c) intercellular spaces
d) nucleus

6) The chemical nature of the carrier molecules facilitating transport
across the plasma membrane is

a) starchy
b) sugary
c) proteinaceous
d) fatty acidic

7) The correct sequence of protein (P) and lipid (L) in
the cell membrane is

a) L-P-L-P
b) L-P-P-L
c) P-L-L-P
d) P-P-L-L

8) The mosaic model of plasma membrane can better explain
permeability by the

a) osmosis
b) diffusion
c) carrier process
d) electrochemical gradient

9) Liquid food drinking by the cell is
a) Pinocytosis
b) Phagocytosis
c) Imbibition
d) None of the above

10) The fluid mosaic model of the cell membrane proposed that
a) A lipid bilayer is coated by a layer of proteins on each face
b) A lipid bilayer is coated by a layer of proteins on the outer surface only
c) A lipid bilayer has proteins embedded in itself and none on the surface
d) A lipid bilayer has both embedded and outer proteins

11) According to the fluid mosaic model, the plasma membrane is
composed of

a) Phospholipids and oligosaccharides
b) Phospholipids and hemicellulose
c) Phospholipids, extrinsic and intrinsic proteins
d) Phospholipids and integral proteins

12) The basic unit of the plasma membrane is
a) protein and phospholipid
b) cellulose and carbohydrate
c) protein and carbohydrate
d) protein and cellulose

13) The latest view regarding the molecular organization of biomembrane
is based upon the

a) molecular model
b) unit membrane model
c) thin lipid model
d) fluid mosaic model

14) The plasma membrane controls
a) solute concentration
b) cell reproduction
c) the regulation of the flow of materials in and out of the cell
d) both (a) and (b)

15) Single-membrane bound cell organelles include
a) endoplasmic reticulum
b) lysosomes
c) spherosomes
d) both (b) and (c)

16) The cell membrane is mainly constituted by lipids, proteins
and carbohydrates. With respect to their mutual proportions,
which of the following statement is correct?

a) all the three are in equal proportion
b) lipids are least in proportion
c) proteins are least in proportion
d) carbohydrates are least in proportion

17) With respect to the proteins, lipids and carbohydrates present in
a cell membrane, which is true ?

a) Carbohydrates are minimum
b) Lipids are minimum
c) Carbohydrates are maximum
d) All three are in equal proportion

18) Pinocytosis and phagocytosis are properties of the
a) cell wall
b) plasmalemma
c) nucleus
d) none of these

19) Carbohydrates are present in the plasmalemma in the
form of

a) glycolipids and glycoproteins
b) cellulose
c) hemicellulose
d) starch

20) Who proposed the concept of unit membrane for the tripartite
structure of lipoproteins?

a) Seifriz
b) Buvat
c) Davson and Danielli
d) Robertson

21) The term amphipathy was coined by
a) Hartley
b) Robertson
c) Fawcett
d) Strasburger

22) Enzymes functional in cells are called
a) Endoenzymes
b) Exoenzymes
c) Apoenzymes
d) Isoenzymes

23) Coenzyme
was discovered by

a) F. Cole
b) F. Lipmann
c) Menten
d) Banting and Best

24) A co-enzyme is
a) An organic or inorganic group that is essential for enzyme activity
b) An organic nonproteinaceous group that is essential for enzyme activity
c) One that shares function of another enzyme
d) the same enzyme found in different organs or tissues

25) Papain acts both in
a) high and low temperature
b) acidic and alkaline medium
c) stomach and mouth
d) all the above

26) Cytochrome oxidase is an example of an
a) exoenzyme
b) endoenzyme
c) coenzyme
d) proenzyme

27) One of the following catalyzes oxidation-reduction reactions:
a) oxidase
b) oxidoreductase
c) oxygenase
d) all the above

28) The word enzyme was coined by
a) Kuhne
b) Sumner
c) Paine
d) Berzeilus

29) The branch of science dealing with biological catalysts is called
a) Biotechnology
b) Biochemistry
c) Enzymology
d) Gerontology

30) …. is the best example of an allosteric protein:
a) Haemoglobin
b) Pepsin
c) Carboxypeptidase
d) Trysin

31) To hydrolyze sucrose in a candy (chocolate coated)
which enzyme is required in a minute quantity

a) pepsin
b) rennin
c) invertase
d) lipase

32) The set of proteolytic enzymes secreted by the pancreas
into the digestive tract is

a) carboxypeptidase; chymotrypsin; trypsin
b) carboxypeptidase, amylase; pepsin
c) rennin; amylase; pepsin
d) all above

33) In plants, enzymes occur in
a) leaves only
b) flowers only
c) all living cells
d) storage organs only

34) Many of the actual sites of an enzyme contain metal ions that enhance
reaction, particularly by helping to bind the substrate or to withdraw
electrons. They are called

a) coenzyme
b) apoenzyme
c) cofactors
d) all above

35) In recent years, the laundry agent (detergent) for presoaking clothes contains the
enzyme

a) pepsin
b) flavin
c) amylase
d) subtilin

36) A coenzyme is
a) always a protein
b) often a metal
c) always an inorganic compound
d) often a vitamin

37) An enzyme can be synthesized by chemically bonding together molecules
of

a) carbohydrates
b) amino acids
c) lipases
d)

38) Enzymes generally have the
a) same pH and temperature optima
b) same pH but different temperature optima
c) different pH but same temperature optima
d) different pH and temperature optima

39) Which of the following is the best evidence of the lock and key
theory of enzyme reaction?

a) all isolated enzymes have been identified as proteins
b) compounds similar in structure to the substrate inhibit enzymatic reactions
c) enzymes found in living organisms speed up certain reactions
d) enzymes determine the direction of reaction

40) The fastest acting enzyme in the biological kingdom is
a) lipase
b) amylase
c) carbodypeptidase
d) carbonic anhydrase

41) If the protein part of the holoenzyme is apo-enzyme then the non-protein
part of enzyme is the

a) prosthetic group
b) cofactor
c) coenzyme
d) all the above

42) One gene, one enzyme concept means
a) one gene controls one enzyme
b) enzyme control gene
c) all enzymes are controlled by genes
d) all genes are controlled by enzymes

43) An allosteric substance influences the enzyme activity by
a) competing for the catalytic site
b) changing the specificity of the enzyme for the substrate
c) changing the conformation of the enzyme by binding to a site other than the catalytic site
d) all above

44) A competitive inhibitor of the enzyme has one of the following
properties

a) It is frequently a feedback inhibitor
b) It becomes covalently attached to an enzyme
c) It interferes with the substrate binding to the enzyme
d) It causes irreversible inactivation of the enzyme

45) An enzyme which catalyses the conversion of aldose sugar to ketose
would be classified as

a) transferase
b) isomerase
c) hydrolase
d) ligase

46) In which of the following types of enzymes is an inducer not required?
a) Allosteric
b) Inhibitory
c) Constitutive
d) All above

47) The enzyme activity model of Fischer implies that
a) the active site is flexible and adjusts to the substrate
b)
c) the active site is complementary in shape to that of the substrate
d) none of the above

48) An enzyme increases the rate of reaction by
a) increasing the free energy of activation
b) decreasing the energy of activation
c) changing the equilibrium constant of the reaction
d) increasing the free energy change of the reaction

49) Which is true ?
a) Holoenzyme = Apoenzyme + Endoenzyme
b) Apoenzyme = holoenzyme + Exoenzyme
c) Co-enzyme = Holoenzyme + Apoenzyme
d) Holoenzyme = Co-enzyme + Apoenzyme

50) The inactive precursor of an enzyme is called
a) apoenzyme
b) proenzyme
c) zymogen
d) both b and c

51) The velocity of a reaction almost doubles with
rise in temperature, which is called the … of an enzyme

a)
b)
c)
d)

52) The inhibition of glutamic dehydrogenase by ATP during cellular
respiration is an example of

a) feedback inhibition
b) competitive inhibition
c) allosteric inhibition
d) both a and b

53) Enzymes are proteins; this was suggested by
a) Pasteur
b) Miler
c) Sumner
d) Waksman

54) The metal activator in ascorbic acid oxidase is
a) Copper
b) Zinc
c) Iron
d) Magnesium

55) Enzymes are useful to plants because
a) they are essential for their metabolic processes
b) they are building blocks of chlorophyll
c) they help in their movements
d) they are made of amino acids

56) Enzymes are basically made up of
a) proteins
b) vitamins
c) fats
d) nucleic acids

57) One of the following is without co-enzyme activity:
a) Biotin
b) Thiamine
c) Riboflavin
d) Vitamin E

58) Which of the following is not an attribute of enzymes?
a) They speed up the rate of biochemical reaction
b) They are specific in nature
c) They are used up during reactions
d) They are proteinaceous in nature

59) Enzymes are absent in
a) fungi
b) bacteria
c) viruses
d) algae

60) Enzymes, vitamins and hormones can be classified into a single
category of biological chemicals because all of them

a) are synthesized in organisms
b) are proteins
c) aid in regulating metabolism
d) are carbohydrates

61) The shape of an enzyme and consequently its activity can be
reversibly altered from moment to moment by

a) heat
b) amino acid substitution
c) allosteric subunits
d) all the above

62) The active site of an enzyme is formed by
a) R groups of amino acids
b) Amino groups of amino acids
c) COOH groups of amino acids
d) Exposed sulphur bonds

63) One of the following is an example of a coenzyme:
a)
b) lipase
c) vitamin B
d) lysine

64) Hydrogen cyanide is an example of a/an
a) coenzyme
b) cofactor
c) non-competitive inhibitor
d) allosteric modulator

65) Which of the following has co-enzyme activity?
a) Purine
b) Pyrimidine
c) Both A and B
d) Nicotinamide

66) Who proposed the induced fit model of the active site of an enzyme?
a) E. Buchner
b) Koshland
c) E. Fischer
d) Kuhne

67) In feedback inhibition, a metabolic pathway is switched off
by

a) a rise in temperature
b) the accumulation of the end product
c) competitive inhibition
d) lack of substrate

68) According to Jacob and Monod, allosteric enzymes are those enzymes whose activity
is regulated by the

a) substrate
b) prosthetic group
c) coenzyme
d) end product

69) Blocking of the active site of an enzyme is a kind of
a) non-competitive inhibition
b) competitive inhibition
c) allosteric inhibition
d) feedback inhibition

70)
is a/an

a) Enzyme activator
b) Hydrogen acceptor
c) Ion carrier
d) Electron acceptor

71) One of the following statements is false for the maximum velocity
(V.max) of an enzyme-catalysed reaction:

a) It is a useful fundamental characteristic property of an enzyme
b) It is measured for the purpose of enzyme assay
c) It can be converted into the reaction velocity at a lower substrate concentration
d) It can be used to deduce the number of active catalytic sites per enzyme molecule

72) A metabolic pathway means a
a) route taken by chemicals through chemical reactions
b) sequence of enzyme-facilitated chemical reactions
c) route taken by a particular enzyme from one chemical reaction to another
d) diagram of how organic molecules evolve

73) In most metabolic pathways, all needed enzymes are arranged
together in a multienzyme complex within a

a) solution of ATP
b) membrane
c) quaternary proteins
d) coenzymes

74) The most commonly known cofactors for enzymes are
a) Zn, Ca
b) Ca, Zn, Co
c) K, Co, Mg
d) All the above

75) Which of the following forms a part of a co-enzyme ?
a) Zn
b) Lipase
c) Riboflavin
d) Lysine

76) Lysoenzymes are located in
a) tears
b) saliva
c) gastric secretions
d) all the above

77) Carbonic anhydrase is the best known example of
a) hydrolase
b) transferase
c) lyase
d) coagulase

78) Which of the following is not true?
Non-competitive inhibitor differs from a competitive inhibitor
in that it

a) reduce the affinity of the substrate for the enzyme
b)
c) may attach itself to the enzyme at a site other than the active site
d) both a and c

79) The catalytic activity of enzymes is influenced by
a) temperature
b) pH and enzyme poisons
c) Concentration, substrate and co-factors
d) All the above

80) The substrate concentration at which an enzyme attains half
of its maximum velocity is known as

a)
b) concentration coefficient
c) Michaelis-Menten constant
d) Half life

81) Which of the following contains a cofactor?
a) Cytochrome-c reductase
b) Ascorbic acid oxidase
c) Both A and B
d) None of the above

82) Which of the following general principles is not true for
zymogen activation?

a) Liberation of activator molecules
b) Hydrolysis of large, inactive precursors
c) Splitting off an inhibitory polypeptide fragment
d) Conformational change bringing certain amino acid residues together

83) How is the rate of an enzyme-catalysed reaction affected by
rise in temperature?

a) doubles
b) becomes four times
c) halves
d) remain unchanged

84) In the case of competitive inhibition of an enzyme
a)
b)
c) the extent of inhibition remains the same at high substrate concentrations
d) none of the above

85) An enzyme functional at pH 6.8 is
a) Pepsin
b) Ptyalin
c) Trypsin
d) Erepsin

86) A distinct domain in the enzyme molecules may
a) contribute to catalytic site
b) bind a coenzyme
c) bind an allosteric effector
d) bind a non-competitive effector

87) Umbarger got the Nobel Prize in 1961 after he discovered
a) allosteric inhibition
b) feedback inhibition
c) competitive inhibition
d) non-competitive inhibition

88) In order to change an inducible system into constitutive
one, at which place will a mutation be most effective?

a) Promotor gene
b) Repressor gene
c) Structural gene
d) Constitutive can be converted to inducible one but not the vice versa

89) Which of the following is an example of a coenzyme?
a) CoA
b) NAD
c) FAD
d) All the above

90) Which of the following enzymes is allosteric?
a) Hexokinase
b) Glucokinase
c) Glucose-6-phosphatase
d) Lipase

91) One of these are exceptional as they survive without
enzymes:

a) Methanobacteria
b) Rickettsia
c) Bacteriophages
d) A few protistans

92) Heat-resistant enzymes are known to occur in
a) Camels
b) Viruses
c) Kangaroo rats
d) Blue-green algae

93) Enzymes are absent in
a) algae
b) plants
c) viruses
d) bacteria

94) The only enzyme which can act as both carboxylase and oxidase
and is most abundant on earth is

a) rubisco
b) FAD
c) NADP
d) FMN

95) Substances which bring about changes in allosteric sites
are called

a) Activators
b) Modulators
c) Promoters
d) Inhibitors

96) A holoenzyme consists of a/an
a) apoenzyme-cofactor complex
b) apoenzyme alone
c) cofactor
d) coenzyme

97) Lock and key hypothesis for enzyme action was given
by

a) Emil Fischer
b) Koshland
c) Endmont
d) Sumner

98) The nature of an enzyme is
a) a vitamin
b) a carbohydrate
c) a polypeptide
d) a fatty acid

99) The enzyme used for the formation of RNA on DNA is
a) DNA polymerase
b) Endonuclease
c) Topoisomerase
d) RNA polymerase

100) Nickel contributes to the formation of one of the following
a) Urease
b) PEP carboxylase
c) Rubisco protein
d) Nitrate reductase

Answers

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