CBSE Questions for Class 12 Engineering Chemistry Biomolecules Quiz 5 - MCQExams.com

Which enzyme converts glucose to ethanol?
  • Diesterase
  • Invertase
  • Zymase
  • Both (2) and (3)
$$6H_{2}O + 6CO_{2}\frac{sunlight} {Chlorophyll}$$ ?
  • $$C_{6}H_{12}O_{6} + 6O_{2}$$
  • $$C_{6}H_{6}O_{6} + 8O_{2}$$
  • $$C_{5}H_{12}O_{17} + CO_{2}$$
  • $$C_{6}H_{11}O_{17} + H_{2}O$$
Amino acids are building blocks of:
  • carbohydrates
  • proteins
  • vitamins
  • fats
A biological catalyst is essentially
  • An enzyme
  • A carbohydrate
  • An amino acid
  • A nitrogenous base
The function of an enzyme is to :
  • Cause chemical reactions that would not otherwise take place
  • Change the rates of chemical reactions
  • Change the directions of reactions
  • Control the equilibrium points of reactions
The polyhydroxy aldehydes are called:
  • proteins
  • fats
  • carbohydrates
  • vitamins
Proteins are the polymers of ________.
  • formaldehydes
  • secondary amines
  • amino acid
  • ammonia
Nucleic acids can be double stranded (ds) or single stranded (ss). The following table gives the composition of bases in four different nucleic acid samples.



Amount of base(%)






A
T
G
C
U
Sample 1

40
40
10
100
Sample 2

10
40
40
10
0
Sample 3

40
0
40
10
10
Sample 4

40
0
20
10
30
Using the information given above, it may be deduced that the samples 1, 2, 3, 4 are
  • 1 : dsDNA, 2 : ssDNA, 3 : ssRNA, 4 : ssRNA.
  • 1 : dsDNA, 2 : ssRNA, 3 : dsDNA, 4 : ssDNA.
  • 1 : ssDNA, 2 : dsDNA, 3 : ssRNA, 4 : dsRNA.
  • 1 : dsDNA, 2 : ssRNA, 3 : ssDNA, 4 : ssDNA.
Metabolic processes in living organisms are catalyzed by _______.
  • Enzymes
  • Nucleotides
  • Nucleosides
  • Lipids
Sucrose doesn't respond to tollen's test. But, it gives a positive result after boiling with conc. $$HCl$$. It is due to the:
  • cleavage of glycosidic linkage
  • formation of glycosidic linkage
  • formation of a compound containing carboxylic acid group
  • isomerization to glucose units
Which of the following are diasaccharides?
  • Lactose
  • Sucrose
  • Cellulose
  • Maltose
Carbohydrates may be:
  • sugars
  • starch
  • polyhydroxy aldehyde/ketones
  • compounds that can be hydrolyzed to sugar
The major role of minor elements inside living organisms is to play role of 
  • Co-factors of enzymes.
  • Building blocks of important amino acids.
  • Constituent of hormones.
  • Binder of cell structure.
If salivary amylase is lacking in the saliva, what will not happen?
  • Proteins breaking down into amino acids.
  • Starch breaking down into sugars.
  • Fats breaking down into fatty acids and glycerol.
  • Absorption of vitamins.
How is the rate of enzyme catalysed reactions affected by 10$$^o$$C rise of temperature?
  • Doubles
  • Becomes four times
  • Halves
  • Remains unchanged
Which of the following principles is not true for zymogen activation?
  • Liberation of activation molecules
  • Hydrolysis of large, inactive precursors
  • Splitting off an inhibitor precursors
  • Conformational change brings certain amino acid residues together
Glycolysis occurs only in the presence of 
  • Ca
  • Mn
  • Mg
  • Co
Which of the following statement is incorrect?
  • Amylose is water soluble component of starch
  • Amylopectin is water insoluble component of starch
  • $$\alpha$$-D Glucose units are present in amylose and amylopectin
  • None of these
An example of disaccharide, made up of two units of the same monosaccharide, is:
  • maltose
  • sucrose
  • lactose
  • none
Which of the following statement is true for enzymes?
  • They lower the activation energy of a reaction by increasing the energy level of the substrate.
  • They lower the activation energy of a reaction by raising the energy level of the product.
  • They do not affect the free energy change between substrate and product.
  • They can be steroids instead of proteins at times.
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 is called as
  • Coenzyme
  • Apoenzyme
  • Cofactor
  • All of the above
Example of coenzyme is
  • CoA
  • NAD
  • FAD
  • All of the above
Coenzyme among the following is
  • Mg$$^{++}$$
  • A part of sRNA
  • A part of tRNA
  • FMN
Cytochrome oxidase is an example of which of the following?
  • Exoenzyme
  • Endoenzyme
  • Coenzyme
  • Proenzyme
A distinct domain in an enzyme molecule may 
  • Contribute to catalytic site
  • Bind a coenzyme
  • Bind an allosteric effector
  • All of the above
The term 'feed back' refers to the effect of
  • Substrate on the rate of enzymatic reaction
  • End products on the rate of enzymatic reaction
  • Enzyme concentration on its rate of reaction
  • An external compound on the rate of enzymatic reactions
..................... is called as inactive precursor of an enzyme.
  • Apoenzyme
  • Proenzyme
  • Zymogen
  • Both B and C
Which among the following are essential chemical components of many coenzymes?
  • Nucleic acids
  • Carbohydrates
  • Vitamins
  • Proteins
What is the meaning of turnover with reference to enzyme?
  • The number of substrate molecules that molecule of an enzyme converts into products per minute.
  • The number of substrate molecules that molecule of an enzyme converts into products per day.
  • The number of substrate molecules that molecule of an enzyme converts into products per hour.
  • The number of substrate molecules that molecule of an enzyme converts into products per second.
Which of the following statement is incorrect for maximum velocity (V$$_{max}$$) of an enzyme catalysed reaction?
  • It is not a fundamental property of an enzyme, since it is dependent on the initial enzyme loading.
  • It is measured for the purpose of enzyme assay.
  • It can be converted into the reaction velocity at a lower substrate concentration.
  • It can be used to deduce the number of active catalytic sites per enzyme molecule.
K$$_m$$ of enzyme is
  • The substrate concentration at 1/2 of maximum velocity of enzyme action.
  • The substrate concentration at maximum velocity of enzyme action.
  • Half of maximum velocity of enzyme at unit substrate concentration at infinite velocity of enzyme action.
  • Substrate concentration at infinite velocity of enzyme action.
Solve the following.
It is known that 5 microgram of an enzyme convert 10 million molecules of substrate to end products per second. To calculate the enzyme's turnover what else must be known?
  • Molecular weight of the enzyme.
  • Molecular weight of the enzyme and substrate both.
  • The molecular weight of substrate only.
  • Molecular weight of end product only.
During the germination of castor seeds, the activity of ................. is very high.
  • $$\alpha$$-amylase
  • $$\beta$$-amylase
  • Protease
  • Lipase
............. is not an example for hydrolases.
  • Phosphatase
  • Protease
  • Amylase
  • Esterase
  • Sucrose
The catalytic efficiency of two different enzymes can be compared by the
  • The K$$_m$$ value
  • The pH optimum value
  • Formation of the product
  • Molecular size of the enzyme
 Michaelis constant (K$$_m$$) of an enzyme which catalyses a single substrate reaction is ...
  • Dependent upon temperature
  • Approximately proportional to the velocity of the reaction
  • Dependent upon enzyme concentration
  • Dependent upon substrate concentration
The substrate concentration at which an enzyme attains half of its maximum velocity is
  • Half life of enzyme
  • K$$_m$$ constant of enzyme
  • Concentration
  • None of the above
Enzymes, vitamins and hormones can be classified into a single category of biological chemicals, because all of these
  • Enhance oxidative metabolism
  • Are conjugated protein
  • Are exclusively synthesized in the body of a living organism
  • Help in regulation of metabolism
Which of the following enzyme is concerned with the transfer of electrons? 
  • Hydrolase
  • Dehydrogenases
  • Transaminases
  • Proteases
The enzymes are sensitive to 
  • Cold
  • Cell wall
  • Temperature
  • Pressure
The catalytic efficiency of two different enzyme can be compared by the
  • The K$$_m$$ value
  • The pH optimum value
  • Formation of the product
  • Molecular size of the enzyme
Vitamin serves the function of
  • An enzyme
  • A coenzyme
  • A substrate
  • A hormone
Which one of the following is related to glucaric acid?
  • saccharin acid
  •  saccharic acid
  • both A&B
  • None of these
What is the chemical nature of the majority of prosthetic groups?
  • Lipoidal
  • Organic
  • Metallic
  • Alkaloidal
Which of the following is not consumed in a biochemical process?
  • Hormone
  • Enzyme
  • Vitamin
  • Nucleotide
The sex hormone, which controls the development and maintenance of pregnancy, is:
  • cortisone
  • thyroxine
  • progesterone
  • estrone
Which of the following carbohydrates is a disaccharide?
  • Glucose
  • Fructose
  • Maltose
  • Lactose
The $$\alpha$$-amino acid which contains the aromatic side chain is:
  • proline
  • tyrosine
  • valine
  • tryptophan
The nucleic acid base having two possible binding sites is:
  • thymine
  • cytosine
  • guanine
  • adenine
A polysaccharide is a polymer of ______.
  • monosaccharides
  • disaccharides
  • both A and B
  • None of these
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