Chemistry #expch001 Important Questions
Ch. 04. Biochemistry #expch_004
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- Histones are rich in
a) Glysine
b) Lysine
c) Arginine
d) both b &c
Answer: d
Explanation
Histones are highly basic proteins abundant in lysine and arginine residues that are found in eukaryotic cell nuclei. They act as spools around which DNA winds to create structural units called nucleosomes. Nucleosomes in turn are wrapped into 30-nanometer fibers that form tightly packed chromatin.
Video Explanation
- Cobalt Containing Vitamin is
a) VitaminB2
b) Vitamin B3
c) Vitamin B12
d) Vitamin B6
Answer: c
Video Explanation
- A mammalian cell contains 18% of
a) proteins
b) fats
c) carbohydrates
d) lipids
Answer: a
Video Explanation
- Which of the following monosaccharides is
the majority found in the human body?
(a) D-type
(b) L-type
(c) LD-types
(d) None of the above
Answer (a)
Video Explanation
- Which of the following is a reducing sugar?
(a) Dihydroxyacetone
(b) Erythrulose
(c) Glucose
(d) All of the above
Answer(d)
Explanation
Reducing sugar are the carbohydrates with free aldehyde and the ketone group while in the non-reducing sugar no such free groups are found; ..
A reducing sugar is any sugar that is capable of acting as a reducing agent. In an alkaline solution, a reducing sugar forms some aldehyde or ketone, which allows it to act as a reducing agent, for example in Benedict’s reagent. In such a reaction, the sugar becomes a carboxylic acid.
All monosaccharides are reducing sugars, along with some disaccharides, some oligosaccharides, and some polysaccharides. The monosaccharides can be divided into two groups: the aldoses, which have an aldehyde group, and the ketoses, which have a ketone group.
Ketoses must first tautomerize to aldoses before they can act as reducing sugars. The common dietary monosaccharides galactose, glucose and fructose are all reducing sugars.
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- Molisch test is used for _.
(a) Lipids
(b) Proteins
(c) Carbohydrates
(d) Flavoproteins
Answer (c)
Explanation
Molisch’s test is a chemical test which is used to check for the presence of carbohydrates in a given analyte. This test is named after Czech-Austrian botanist Hans Molisch, who is credited with its discovery. Molisch’s test involves the addition of Molisch’s reagent (a solution of α-naphthol in ethanol) to the analyte and the subsequent addition of a few drops of concentrated H2SO4 (sulphuric acid) to the mixture.
The formation of a purple or a purplish-red ring at the point of contact between the H2SO4 and the analyte + Molisch’s reagent mixture confirms the presence of carbohydrates in the analyte.
Video Explanation
- Amino acids are mostly synthesized from
(a) fatty acids
(b) mineral salts
(c) 𝜶-ketoglutaric acid
(d) volatile acids
Answer (c)
Explanation
Amino acids are usually synthesized from α-ketoglutaric acid. It is the precursor of amino acids. Krebs cycle yields a five-carbon compound, it is α-ketoglutaric acid which is the first dicarboxylic acid to form. α-ketoglutaric acid is converted into glutamic acid, Pyruvic acid into alanine, OAA into aspartic acid.
Video Explanation
- Absorbance at 280nm is exhibited by proteins is due to
(a) aliphatic amino acids
(b) aromatic amino acids
(c) all amino acids
(d) none of these
Answer (b)
Explanation
Proteins primarily absorb UV light due to the presence of tryptophan, tyrosine, and phenylalanine residues, with absorbance maxima at 280, 275, and 258 nm, respectively.
Video Explanation
- The degree of unsaturation of lipids can be measured as
(a) Iodine number
(b) Saponification number
(c) Reichert Meissel number
(d) Polenske number
Answer: (a)
Explanation
Iodine value can be used to measure the degree of unsaturation of oils and fats. The results are normally expressed as the number of grams of iodine absorbed by 100 g of oil or fat, considering the conditions of the test.
Video Explanation
- Nucleic acids combine with which biomolecule??
Fats
Lipids
Carbohydrates
Proteins
Explanation
Combination of proteins with nucleic acids gives nucleoproteins. Nucleic acids are the prosthetic group present in nucleoproteins. Nucleoproteins are proteins of cell nuclei and are main component of chromatin. They are present in every living cell a well as in virus and bacteria.
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- The compound does not contain the phosphate group, is?
Nucleotide
Nucleoside
Both A & B
None of these
Answer : b
Video Explanation
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13- Which of the following is purine nucleotide?
Adenin
Uracil
Thymine
All of the above
Answer: a
Video Explanation
14- Phosphate group is attached to which carbon of pentose sugar?
C-1
C-2
C-4
C-5
Answer: d
Video Explanation
15- Which ratio is constant for DNA?
A + G / T + C
A + T / G + C
A + C / U + G
A + U / G + C
Answer: a
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