Test: Amines & Biomolecules (March 6) - NEET MCQ

The correct answer is option B.
Amylopectin is insoluble in water and constitutes about 80−85% of starch. It is a branched-chain polymer of −D− glucose units in which chain is formed by C1−C4 glycosidic linkage whereas branching occurs by C1−C6 glycosidic linkage. Glycogen: The carbohydrates are stored in the animal body as glycogen. It is also known as animal starch because its structure is similar to amylopectin and is rather more highly branched.

The correct answer is Option C.
Glucose is an aldohexose having structural formula.

Glucose on heating with HI produces n hexane.
C₆H₁₂O_{6 --HI}→C₆H₁₄
Glucose does not give 2,4. DNP test due to its existence as cyclic structure shown below :

It is present in pyranose form, as shown below 

Pyranose means pyran (membered ring containing oxygen) like structure.

Glycogen is a branched chain polymer of αD glucose units in which chain is formed by C₁−C₄ glycosidic linkage whereas branchin occurs by the formation of C₁−C₆ glycosidic linkage. Structure of glycogen can be shown below similar to the sturcture amplopectin.

The correct answer is option C
CH_3​CH₂​CONH₂​ (A)⟶ CH₃​ − CH₂ ​− NH₂​ (B)⟶ ​CH_3​ − CH₂ ​− OH
In the above sequence A & B respectively are Br₂​/KOH and HNO₂​
The first step is Hoffmann bromamide degradation reaction in which an amide (propanamide) is converted to an amine  (ethylamine) containing one carbon atom less. The reagent A is bromine in presence of KOH. In the second step, aliphatic primary amine (ethyl amine) reacts with nitrous acid (reagent B) to form aliphatic primary alcohol (ethyl alcohol).
 

Hoffmann Bromamide reaction is Treatment of alkylamide with KOH and Bromine gas which converts it into alkylamine with one less carbon atom, this reaction is generally helpful in converting Carboxylic acids to amines with one less carbon atom . For reaction you may refer to internet but i can give you a hint .

Acetamide + KOH + Bromine gas —-> Alkylamine+ KBr + K2CO3 + H20 ( not sure about the products)

Due to absence of free OH group at C₂ cyclic structure of glucose pentacetate cannot revert to open chain aldehydic form and hence cannot form an oxime. 

The correct answer is option A
Nucleotides are joined together by phosphodiester linkage between 5′ and 3′ carbon atoms of pentose sugar.
 

The correct answer is option C
'a' carbon of glucose and 'b' carbon of fructose
Carbon adjacent to the oxygen atom in the cyclic structure of glucose or fructose is known as anomeric carbon. As shown in the structure above ‘a’ and ‘b’ are present adjacent to an oxygen atom. Both carbons differ in configurations of the hydroxyl group.

Options A is correct.
In lysine,the amino group is attached to alpha carbon which makes it alpha amino acid and it has more amino groups as compared to -COOH groups, thus basic.

The correct answer is option A
Reduction with LiAlH₄

 

 Flavor, texture and shortening are all major culinary uses of oil in the food industry.

The correct answer are options B.
In fibrous proteins, polypeptide chains are held together by hydrogen and disulphide bonds, in parallel manner. Due to which fibre-like structure is obtained. Such proteins are generally known as fibrous proteins. These proteins are generally insoluble in water e.g., keratin, myosin.

LiAlH₄ reduces all oxiginated functional groups to alcohol and all nitrogenated functional groups to amine thus cyanide is a nitrogenated functional group and to convert cyanide to amine LiAlH4 can be used.

The correct answer is option  D
Vitamin B₁₂
The body has a limited capacity to store most of the B-group vitamins except B₁₂ and folate, which are stored in the liver.

The correct answer is D. Both b and c.
One of the common disaccharides is sucrose which on hydrolysis gives an equimolar mixture of D−(+)− glucose and D−(−) fructose. These two monosaccharides are held together by a glycosidic linkage between Cl of α- glucose and C2 of β- fructose. Since the reducing groups of glucose and fructose are involved in glycosidic bond formation, sucrose is a non-reducing sugar.

The primary structure of a protein refers to the sequence of amino acids in the polypeptide chain. The primary structure is held together by peptide bonds that are made during the process ofprotein biosynthesis.

Nucleotides are organic molecules that serve as the monomer units for forming the nucleic acid polymers deoxyribonucleic acid and ribonucleic acid, both of which are essential biomolecules within all life-forms on Earth.

The correct answer is option A
Life is possible due to the coordination of various chemical reactions in living organisms. This occurs with the help of certain biocatalysts called enzymes. Almost all the enzymes are globular protein.

The correct answer is option D
The chemical reaction used for transforming primary alkyl halides into primary amines is called Gabriel phthalimide synthesis. It uses potassium phthalimide. Therefore, Gabriel phthalimide synthesis is used in the preparation of 1o
amide.

Structures (I and II) differ only in the position of OH at C₂ and hence are anomers. 

Correct answer is A. Guanine

Aniline is prepared commercially by the catalytic hydrogenation of nitrobenzene or by the action of ammonia on chlorobenzene. The reduction of nitrobenzene can also be carried out with iron borings in aqueous acid. A primary aromatic amine, aniline is a weak base and forms salts with mineral acids.

Quinoline is an alkaloid, it is not present in DNA. DNA  has four nitrogen bases in adenine, guanine, cytosine and  thymine

In α-helix, hydrogen bonds are present between –NH group of one amino acid residue to the >C= O group of another aminoacid residue.

The correct answer is Option C.

(i)   The first structure is lactose, the linkage is (A) C₁−C₄ glycosidic linkage.
(ii)  The 2_nd structure has C₁−C₆ linkages.
(iii) The 3_rd structure has C₁−C₄ linkages.

The correct answer is A .
The structure of protein which results when the chain of polypeptides coil around to give a spherical shape are known as globular protein. These proteins are soluble in water, e.g., insulin and albumin are globular protein.

If blood glucose levels become too low, glucagon (pancreatic hormone) is released, which causes the liver to convert the stored glycogen back into glucose, and release it into the bloodstream.