Chapter 31

Which one of the following compounds exists as a dipolar ion? (a) carbohydrate (b) amino acid (c) long chain fatty acids (d) \(\alpha\)-halo carbonyl compound

The number of tripeptides formed by 3 different amino acids are? (a) 3 (b) 4 (c) 5 (d) 6

Which of the following contain prosthetic group? (a) glycoprotein (b) haemoglobin (c) nucleoprotein (d) all of these

In biological systems, the RNA molecules direct the synthesis of specific proteins which are characteristics of each kind of organism. This process is known as (a) transcription (b) mutation (c) replication (d) translation

Phospholipids are esters of glycerol with (a) two carboxylic acid residues and one phosphate group (b) one carboxylic acid residue and two phosphate groups (c) three phosphate groups (d) three carboxylic acid residues

The base found in DNA but not in RNA is (a) cytosine (b) guanine (c) thymine (d) adenine

Which of the following has magnesium? (a) carbonic anhydrase (b) haemocyanin (c) chlorophyll (d) Vitamin \(\mathrm{B}_{12}\)

An example for a saturated fatty acid, present in nature is (a) oleic acid (b) linoleic acid (c) linolenic acid (d) palmitic acid

The group linkage present in fats is (a) peptide linkage (b) ester linkage (c) glycosidic linkage (d) none of these

The group present in waxes are (a) acid group (b) ester group (c) alcoholic group (d) ether group

RNA and DNA are chiral molecules, their chirality is due to (a) L-sugar component (b) Chiral bases (c) Chiral phosphate ester units (d) D-sugar component

The pair in which both the compounds give positive test with Tollen's reagent is (a) fructose and sucrose (b) acetophenone and hexanal (c) glucose and sucrose (d) glucose and fructose

Which one of the following is the first member of monosaccharides? (a) \(\mathrm{CH}_{2} \mathrm{OH}-\mathrm{CHOH}-\mathrm{CHO}\) (b) COC(=O)CO (c) COC(O)C(=O)CO (d) \(\mathrm{CH}_{2} \mathrm{OH}-\mathrm{CHOH}-\mathrm{CHOH}-\mathrm{CHO}\)

Glucose reacts with bromine water to produce (a) glyceraldehyde (b) gluconic acid (c) saccharic acid (d) glutaric acid

Choose the correct relationship for \(\alpha\)-D-glucose (A) and \(\beta\)-D-glucose (B). (a) \(\mathrm{A}\) and \(\mathrm{B}\) are crystal modification (b) A and B are epimers (c) A is an aldose and \(\mathrm{B}\) is a ketose (d) A is a pyranose sugar and \(\mathrm{B}\) is a furanose sugar

Maximum number of monosaccharide units present in oligosaccharides is (a) 5 (b) 10 (c) 15 (d) 20

Consider the following reaction Reagents Glucose \(\stackrel{\text { Nagent }}{\longrightarrow}\) Mannose This reaction is known as (a) conversion (b) epimerization (c) racemization (d) anomerization

Sanger's reagent is used for the identification of (a) \(\mathrm{C}\) - terminal of a peptide chain (b) \(\mathrm{N}-\) terminal of a peptide chain (c) number of amino acids in a peptide chain (d) side chain of amino acids

Mutarotation does not occur in (a) \(\mathrm{L}\) - glucose (b) D- glucose (c) sucrose (d) none of these

In the following reaction: Glucose \(+3 \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}-\mathrm{NH}_{2} \stackrel{\mathrm{H}^{+} / \mathrm{U}}{\longrightarrow}\) Osazone \(+\mathrm{X}+\mathrm{Y}\) \((\mathrm{X})\) and \((\mathrm{Y})\) are (a) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}\) and \(\mathrm{NH}_{2} \mathrm{OH}\) (b) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}\) and \(\mathrm{NH}_{3}\) (c) \(\mathrm{NH}_{2} \mathrm{OH}\) and \(\mathrm{H}_{2} \mathrm{O}\) (d) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}-\mathrm{NHOH}\) and \(\mathrm{NH}_{3}\)

Which substance chars when heated with conc. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) ? (a) protein (b) hydrocarbon (c) fat (d) carbohydrate

In most of the cases glycosidic linkage is formed between (a) \(\left(1 \longrightarrow 4^{\prime}\right)\) (b) \(\left(4 \longrightarrow 4^{\prime}\right)\) (c) \(\left(2 \longrightarrow 2^{\prime}\right)\) (d) \(\left(1 \longrightarrow 3^{\prime}\right)\)

Which statement is incorrect about peptide bond? (a) \(\mathrm{C}-\mathrm{N}\) bond length in proteins is smaller than usual bond length of \(\mathrm{C}-\mathrm{N}\) bond (b) spectroscopic analysis shows planar structure \(-\) C-NH-bond (c) \(\mathrm{C}-\mathrm{N}\) bond length in proteins is longer than usual bond length of \(\mathrm{C}-\mathrm{N}\) bond (d) none of these

The correct statement about protein haemoglobin is that it (a) maintains blood sugar level (b) acts as an oxygen carrier in the blood (c) functions as a catalyst for biological reactions (d) forms antibodies and offers resistance to diseases

Amylose and cellulose both are liner polymers of glucose. The difference between them is (a) Amylose has \(\beta(1 \longrightarrow 4\) ) linkage and celulose has \(\beta(1 \longrightarrow 6)\) linkage (b) Amylose has \(\alpha(1 \longrightarrow 4)\) linkage and cellulose has \(\alpha(1 \longrightarrow 6)\) linkage (c) Amylose has \(\alpha(1 \longrightarrow 4)\) linkage and cellulose has \(\beta(1 \longrightarrow 4)\) linkage (d) Amylose has \(\beta(1 \longrightarrow 4)\) linkage and cellulose has \(\alpha(1 \longrightarrow 4)\) linkage

Which one of the following statements is true for protein synthesis (translation)? (a) amino acids are directly recognized by \(\mathrm{m}\)-RNA (b) the third base of the codon is less specific (c) only one codon codes for an amino acid (d) every t-RNA molecule has more than one amino acid attachment.

In the following reaction Cellulose \(\stackrel{\text { (i) } \mathrm{CS}_{2} / \mathrm{NaOH}}{\text { (ii) } \mathrm{HCl} / \mathrm{HOH}}-[\mathrm{P}]\) Here, the product [P] is (a) rayon (b) cellulose acetate (c) gun cotton (d) cellulose xanthate

Which of the following are correct? 1 acetyl salicyclic is acid is known as aspirin 2 the compound formed in the addition of oxygen to haemoglobin is called oxy haemoglobin 3 chlorophyll is responsible for the synthesis of carbohydrates in plants 4 the metal ion present in vitamin \(\mathrm{B}_{12}\) is \(\mathrm{Mg}^{2+}\) (a) 1,2 and 3 (b) 2,3 and 4 (c) 1,2 and 4 (d) 2 and 3 only

The reaction of glucose with methyl alcohol in the presence of dry \(\mathrm{HCl}\) shows that is a (a) cyclic hemiaceta (b) polyhydroxy ketone (c) polyhydroxy alcohol (d) polyhydroxy aldehyde

Which one of the following biomolecules is insoluble in water? (a) \(\alpha\)-keratin (b) haemoglobin (c) ribonuclease (d) adenine

Sucrose itself is a non reduction sugar. It is due to (a) the linkage of both the anomeric carbon atoms in an acetal form (b) the presence of \(\alpha\)-hydroxy keto group in its structure (c) the presence of equal amount of \(\mathrm{D}(+)\) glucose and \(\mathrm{D}(-)\) fructose (d) the easy conversion of sucrose into invert sugar on hydrolysis

Glucose is different from fructose as (a) does not undergo hydrolysis (b) gives silver mirror with Tollen's reagent (c) is a monosaccharide (d) none of these

Which functional group participates in disulphide bond formation in proteins? (a) thioester (b) thioether (c) thiol (d) thioacetone

A certain compound gives negative test with ninhydrin and positive test with Benedict's solution. The compound is (a) a protein (b) a monosaccharide (c) a lipid (d) an amino acid

In the given polypeptideArg-Try-Ile-Asn-Gly C-terminus amino acid is (a) Arg (b) Try (c) Gly (d) Asn

The carbohydrate which cannot be hydrolyzed by the human digestive system is (a) starch (b) cellulose (c) glycogen (d) all of these

If in an amino acid, the carboxylic group ionizes at \(\mathrm{pKa}_{1}=2.34\) and the ammonium ion at \(\mathrm{pKa}_{2}=9.60 .\) The isoelectric point of the amino acid is (a) \(2.36\) (b) \(5.97\) (c) \(6.86\) (d) \(7.58\)

Hydrolysis of lactose with dilute acid yields (a) equimolar mixture of D-glucose and D-glucose (b) equimolar mixture of D-glucose and Dgalactose (c) equimolar mixture of D-glucose and D-fructose (d) equimolar mixture of D-galactose and Dgala-ctose

2, 4-dinitrofluorobenzene is used in peptide chemistry because (a) it makes the amino acids insoluble in water and thus making them readily crystallizable (b) it undergoes electrophilic substitution (c) it undergoes nucleophilic substitution (d) it has a characteristic colour

Sucrose on hydrolysis gives (a) glucose + glucose (b) glucose + galactose (c) glucose \(+\) fructose (d) glucose \(+\) lactose

State the correct general formula of carbohydrates (a) \(\mathrm{C}_{x}\left(\mathrm{H}_{2}\right)_{y} \mathrm{O}\) (b) \(\mathrm{C}_{x-1}\left(\mathrm{H}_{2} \mathrm{O}\right)_{y}\) (c) \(\mathrm{C}_{r}\left(\mathrm{H}_{2} \mathrm{O}\right)_{y}\) (d) \(\mathrm{C}_{x}\left(\mathrm{H}_{2} \mathrm{O}\right)_{v+2}\)

In addition to aldehyde group glucose contains (a) one secondary OH and four primary OH groups (b) one primary OH and four secondary OH groups (c) two primary \(\mathrm{OH}\) and three secondary OH groups (d) three primary OH and two secondary OH groups

Thymine is (a) 5 -methyluracil (b) 4 -methyluracil (c) 3-methyluracil (d) 1-methyluracil

Lysine is best soluble in water in the \(\mathrm{pH}\) range (a) 3 to 4 (b) 5 to 6 (c) 6 to 7 (d) 8 to 9

Methyl- \(\alpha\)-D-glucoside and methyl-\beta-D-glucoside are (a) epimers (b) anomers (c) enantiomers (d) conformational diastereomers

Which of the following statements is correct? (a) the metal ion present in vitamin \(\mathrm{B}_{12}\) is \(\mathrm{Zn}^{2+}\) (b) in photosynthesis \(\mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\) are converted into carbohydrates in presence of sunlight (c) in haemoglobin the oxidation state of \(\mathrm{Fe}\) is \(+6\). (d) methyl salicylate is known as aspirin

The number of hydrogen bonds formed between in the sequence of a stretch of a double helical DNA 5'ATGCCTAA3' is (a) 15 (b) 19 (c) 29 (d) 12

Consider the following statements about sucrose. 1\. hydrolysis of sucrose with dilute acid yields an equimolar mixture of D-glucose and D-fructose 2\. acid hydrolysis of sucrose is accompanied by a change in optical rotation 3\. in sucrose, the glycosidic linkage is between C-1 of glucose and \(\mathrm{C}-2\) of fructose 4\. aqueous solution of sucrose exhibits mutarotation Which of the statements are correct? (a) 1 and 2 only (b) 2 and 3 only (c) 1,2 and 3 (d) 1,3 and 4

Glucose and fructose give the same osazone. One may, therefore conclude that (a) the structures of glucose and fructose have mirror image relationship (b) glucose and fructose have identical structures (c) the structures of glucose and fructose differ only in those carbon atoms which take part in osazone formation (d) glucose and fructose are anomers

Which one of the following pairs is incorrectly matched? (a) sucrose 1\. monosaccharide (b) fructose 2\. aldose sugar