CBSE Questions for Class 12 Engineering Chemistry Biomolecules Quiz 13 - MCQExams.com

The reduction in the enzyme activity takes place by
I. Decreasing pH level
II. Increasing temperature
III. Placing enzyme in a non polar liquid
  • I only
  • II only
  • III only
  • I and II
  • I, II, and III
The amino acid containing indole part is :
  • Tryptophan
  • Tyrosine
  • Proline
  • Methionine
 Match the following list and choose the correct combination.
List-AList-B
(A) Oxidoreductases (i) Linking of two compounds
(B) Isomerase(ii) Removal of groups from substrates
(C) Ligases (iii) Inter conversion of isomers
(D) Lyases(iv) Dehydrogenation 
(v) Hydrolysis
  • A- (iv), B- (i), C- (iii), D- (ii)
  • A- (iv), B- (iii), C- (i), D- (ii)
  • A- (iii), B- (iv), C- (ii), D- (v)
  • A- (ii), B- (v), C- (iii), D- (i)
Which one of the following is not true for enzymes? 
  • They act on a specific substrate.
  • They are made up of fat and sugar.
  • They act at a specific temperature.
  • They act at a specific pH.
The Michaelis constant $${K _m}$$ is equal to
  • $${\frac{K_1}{K_2-K_3}}$$
  • $${\frac{K_2+K_3}{K_1}}$$
  • $${\frac{K_2-K_3}{K_1}}$$
  • $${\frac{K_1\times K_2}{K_3}}$$
Which of the following is aromatic?
  • Lysine
  • Proline
  • Serine
  • Tyrosine
Negative feedback is defined as a decrease in function in response to a stimulus. In negative feedback, an output of a particular system or reaction is decreased. Positive feedback, is an increase in function in response to a stimulus. In positive feedback, an output is enhanced.
All of the following are examples of negative feedback except
  • The regulation of human body temperature in which the body shivers to bring up the temperature and sweats to cool down.
  • The control of hunger in which metabolism slows down to conserve energy and to allow the organism to survive with less food.
  • The formation of a blood clot where once a vessel is damaged, platelets stick to the injured site and release chemicals that attract more platelets until a clot is formed.
  • The production of red blood cells that results from a decrease in oxygen detected by the kidneys which secretes a hormone that stimulates the production of red blood cells.
Read the given passage.
In bacteria -galactosidase (gal) is an enzyme which is used for lactose metabolism. The human intestinal bacteria of three different groups were cultured in a medium containing glucose. At time 1, the bacteria were transferred to media containing lactose as a nutrient source instead of glucose. At time 2, the bacteria were returned to the medium containing glucose. Samples of bacteria were removed at five-minute intervals and tested for the presence of gal. The results are presented by graph.
The induction of gal production by intestinal bacteria in this way is useful because

481246_b2b7d3ee176e4907bdda7569237b8b13.png
  • Humans do not consume foods containing lactose all the time.
  • It prevents toxic buildup of lactic acid.
  • The production of gal is harmful to bacteria.
  • It prevents the bacteria from using glucose as a nutrient source.
  • Lactose is harmful to bacteria.
Which of the following is a chemical messenger that is produced from one part of the body but affects a different body region?
  • Hormones
  • Minerals
  • Endocrines
  • Both A and C
Read the following passage and answer the following questions.
Beta-galactosidase (Beta-gal) is a bacterial enzyme used in the metabolism of lactose. Three different groups of human intestinal bacteria were cultured in a glucose-based medium. At Time 1, the bacteria were transferred to media containing lactose as a nutrient source instead of glucose. At Time 2, the bacteria were returned to the glucose-based medium. Samples of bacteria were removed at five-minute intervals and tested for the presence of -gal. The results are presented below.
What could account for the delay in -gal production after Time 1 seen in Group 1?
  • An inability to synthesize -gal
  • Transcription of -gal mRNA
  • Continued use of glucose as a nutrient
  • Replication of the bacterial DNA
  • Infection by a virus
Which of the following is a physical property of sugar?
  • It is a white crystalline solid.
  • Carbon, hydrogen, and oxygen are its constituents.
  • It turns black when concentrated $$\displaystyle { H }_{ 2 }{ SO }_{ 4 } $$ reacts with it.
  • When heated it decomposes.
  • It decomposes readily.
Artificial sweetener which is 600 times sweeter than sucrose is:
  • aspartame
  • alitame
  • sucralose
  • saccharin
The statement that is not correct is :
  • carbohydrates are optically active
  • lactose has glycosidic linkage between $${ C }_{ 4 }$$ of glucose and $${ C }_{ 1 }$$ of galactose unit
  • aldose or ketose sugars in alkaline medium do not isomerise
  • penta acetate of glucose does not react with hydroxylamine
GH promotes :
  • bone growth
  • cell division
  • protein synthesis
  • all of the above
First scientist to find out protein nature of enzyme was
  • Kuhne
  • Buchner
  • Sumner
  • Altman et al
Which of the following refers to particularly stable arrangements of amino acid residues in a protein that give rise to recurring patterns?
  • Primary structure
  • Secondary structure
  • Tertiary structure
  • Quaternary structure
Enzyme was first isolated by
  • Kuhne
  • Sumner
  • Payer and Persoz
  • Buchner
Which of the following statements is/are correct regarding the effects of pH on enzyme catalysed reactions? 
  • Direction of the reaction is influenced by $$[H^+]$$.
  • Ionization state of dissociating groups on the enzyme is modified.
  • Ionization state of the substrate is modified.
  • All of the above
In the study of enzymes, a sigmoidal plot of substrate concentration(S) versus the reaction velocity(V) indicates
  • Michaelis- Menten kinetics
  • Cooperative binding
  • Competitive inhibition
  • Non-Competitive inhibition
In double strand helix structure of DNA, heterocyclic base cytosine forms hydrogen bond with:
  • adenine
  • guanine
  • purine
  • thymine
  • uracil
Carbohydrate digestion begins in
  • Stomach
  • Mouth
  • Intestine
  • All the above
Nongenetic RNA is of
  • Two types
  • Three types
  • Four types
  • One type
All enzymes of TCA cycle are located in the mitochondrial matrix except one which is located in inner mitochondrial membranes in eukaryotes and in cytosol in prokaryotes. This enzyme is?
  • Lactate dehydrogenase
  • Isocitrate dehydrogenase
  • Malate dehydrogenase
  • Succinate dehydrogenae
How many amino acids are present in insulin?
  • $$25$$
  • $$51$$
  • $$20$$
  • $$22$$
  • $$52$$
Which gives only glucose by hydrolysis?
  • Sucrose
  • Raffinose
  • Maltose
  • Galactose
The following tripeptide can be represented as.

739802_95c1a1357faf4c9899243dacb3ec224c.png
  • $$Tyr-Val-Thr$$
  • $$Phe-Ala-Ser$$
  • $$Phe-Leu-Cys$$
  • $$Lys-Ala-Ser$$
The sugar moiety present in $$RNA$$ molecule is:
  • $$\beta - D - 2 -$$ deoxyribose
  • $$\beta - D -$$ galactose
  • $$\beta - D -$$ fructofuranose
  • $$\beta - D -$$ ribose
  • $$\beta - D -3-$$ ribose
In the study of enzymes, a sigmoid plot of  ___________ may indicate Michaelis-Menten kinetics.
  • Substrate concentration[s] versus reaction velocity[v]
  • Product concentration[p] versus reaction velocity[v]
  • Substrate concentration[s] versus product concentration[p] 
  • Substrate concentration[s] versus enzyme concentration[e] 
Which of the following categories of macromolecules includes representatives that  frequently serve as energy storage molecules?
  • Proteins
  • Lipids
  • Carbohydrates
  • Both lipids and carbohydrates
The shape of an enzyme, and consequently its activity, can be reversibly altered from moment to moment by
  • Amino acid substitutions
  • Allosteric subunits
  • Sulphur substitutions
  • High pH
Among the following L-serine is:
Given are the structures of cyclic D-glucoside.

Moles of $$HCHO$$ formed are:

992804_602dd400858f42dd9012c9006314f147.png
  • $$1, 1$$
  • $$2, 2$$
  • $$1, 2$$
  • $$2, 1$$
Of the following chemicals, which one is used as a substitute for sugar? 
  • Insulin
  • Saccharin
  • Vanilla
  • Casein
The given osazone can be obtained by:
995892_491ee48f9b314d80bf4d24dad10f1635.jpg
  • D-glucose
  • D-mannose
  • D-Iodose
  • Both (a) & (b)
Which one out of A - D given below correctly represents the structural formula of a basic amino acid?
887668_e94561c4a2ea4fef8a88d61059ad0768.JPG
  • C
  • D
  • A
  • B
Amino acids are classified as acidic, basic or neutral depending upon the relative number of amino and carboxyl groups in their molecule. Which of the following are acidic?


(i)      $$(CH_3)_2 CH - \underset{NH_2}{\underset{\!\!\!\!|}{CH}} - COOH$$


(ii)      $$HOOC - CH_2 - CH_2 - \underset{NH_2}{\underset{\!\!\!\!|}{CH}} - COOH$$


(iii)      $$NH_2 - CH_2 - CH_2 - CH_2 - COOH$$


(iv)      $$HOOC - CH_2 - \underset{NH_2}{\underset{\!\!\!\!|}{CH}} - COOH$$
  • (ii) and (iv)
  • (iii) and (iv)
  • (i) and (ii)
  • (ii) and (iii)
Which statement correctly completes the statement?
Except for glycerine, which is achiral, all the amino acids present in proteins.:
  • $$H_3 \overset{+}{N}\overset{R}{\overset{|}{C}}H CO_2H$$
    are chiral, but racemic
  • $$H_2 N\overset{R}{\overset{|}{C}}HCO_2H$$
    have the L configuration at their $$\alpha$$ carbon
  • $$H_3 \overset{+}{N} \overset{R}{\overset{|}{C}} H CO^-_2$$
    have the R configuration at their $$\alpha$$ carbon
  • $$H_2N\overset{R}{\overset{|}{C}}H CO_2^-$$
    have the S configuration at their $$\alpha$$ carbon
Among the following, the incorrect statement is:
  • Cellulose and amylose has 1,4-glycosidic linkage
  • Maltose and lactose has 1,4-glycosidic linkage
  • Lactose contains $$\beta$$- D-galactose and $$\beta$$-D-glucose
  • Sucrose and amylose has 1,2-glycosidic linkages
Amino acid having?
1137176_7d620c94ca3541fd855f8a2c9dd544bf.PNG
  • Two $${NH}_{2}$$ groups
  • One $$-COOH$$ group
  • Two $$-COOH$$ group
  • Three $$-COOH$$ groups
Which of the molecules below will react with $$Ag^{+}$$?
996294_2a794a46b8a549c29593785a4124cdbe.jpg
  • (i), (ii) and (iv)
  • (ii) and (iv)
  • (iv) and (vi)
  • (i), (ii), (iii) and (iv)
Which of the following is not an alpha-amino acid?
  • Alanine
  • Guanine
  • Glycine
  • Benzidine
Which one of the following reactions is incorrect? 
  • $$Maltose + H_2O \overset{Maltase}{\rightarrow} Glucose+ Fructose$$
  • $$Sucrose + H_2O \overset{Invertase}{\rightarrow} Glucose+ Fructose$$
  • $$Glucose + H_2O \overset{Zymase}{\rightarrow} Ethyl \, alcohol+CO_2$$
  • $$Starch + H_2O \overset{Diastase}{\rightarrow} Glucose \,only$$
Jitesh carried out a steady-state kinetics experiment for an enzyme degradase with and without molecule X as pat of the reaction mixture. The reactions were carried out for $$5$$ minutes and he got the following results:
Substrate Concentration (milliMolar)  Amount of product formed without X (milliMoles)Amount of product formed with X (milliMoles)
0.10.40.2
0.52.11.3
1.04.32.7
1.56.24.1
2.08.15.4
2.58.36.7
3.08.48.1
3.58.58.3
  • Molecule X is a competitive inhibitor
  • Molecule X is a allosteric inhibitor
  • Molecule X is a cofactor
  • Molecule X has no effect on cataysis
First enzyme to be isolated in pure crystalline from was 
  • Zymase
  • Urease
  • Invertase
  • Diastase
The difference between amylose and amylopectin is :
  • Amlyopectin have $$1\rightarrow 4\alpha-$$ linkage and $$1\rightarrow 6\beta -$$ linkage
  • Amlyopectin have $$1\rightarrow 4\alpha-$$ linkage and $$1\rightarrow 6\alpha -$$ linkage
  • Amylose is made up of glucose and galactose
  • Amylose have $$1\rightarrow 4\alpha-$$ linkage and $$1\rightarrow 6\beta -$$ linkage
Read the statements given below and mark the correct option.
  • Apoenzymes are non- proteinaceous prosthetic groups
  • Bell- shaped curve is obtained when enzyme activity is plotted against factors such pH & temperature
  • Specificity of enzyme action is a property of tertiary structure of proteins usually
  • Enzymes increase rate of reaction by altering the equilibrium of reaction
Which of the following structure is L-arabinose?
Carbohydrates Contains:
  • $$-CHO$$ group
  • $$-OH$$ group
  • $$> C=O$$ group
  • All
Which of the following is not a macromolecule?
  • Nucleic acid
  • Starch
  • Protein
  • Sucrose
In a double stand DNA percentage of adenine  (A) in bases is $$22\%$$ then $$\%$$ of guanine (G) is: 
  • $$28\%$$
  • $$44\%$$
  • $$50\%$$
  • $$60\%$$
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