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 Multiple Choice QuestionsMultiple Choice Questions

1.

Which of the metabolites is common to respiration mediated breakdown of fats, carbohydrates and proteins?

  • Glucose-6-phosphate

  • Fructose 1, 6-biphosphate

  • Pyruvic acid

  • Acetyl Co-A


D.

Acetyl Co-A

Acetyl Co-A is common to respiration mediated breakdown of fats, carbohydrates and proteins Glucose and fructose are phosphorylated to give rise to glucose-6- phosphate by the activity to the enzyme hexokinase.
Glucose -6- phosphate then converts into fructose 6 phosphate and further to fructose 1-6- biphosphate. Pyruvic acid is the end product of glycolysis. 

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2.

Which one of the following is a non-reducing carbohydrate?

  • Maltose

  • Sucrose

  • Lactose

  • Ribose 5 - phosphate


B.

Sucrose

Sucrose is a disaccharide of glucose 8 fructose. It is a non- reducing sugar as it do not contain any free anomeric c arbon atom. Maltose is a disaccharide of 2 glucose units. Its first glucose residue cannot undergo oxidation, whereas, second residue can undergo oxidation because it has a reactive free anomeric carbon atom. Hence, it is a reducing sugar. 

Lactose and ribose - 5- phosphate are also reducing in nature due to the presence of a free ketonic or aldehyde group.

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3.

Which one of the following statements is wrong?

  • cellulose is a polysaccharide

  • Uracil is a pyrimidine

  • Glycine is a sulphur containing amino acid

  • Sucrose is a disaccharide


C.

Glycine is a sulphur containing amino acid

Glycine does not contain sulphur

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4.

Macromolecule chitin is

  • Nitrogen containing polysaccharide

  • phosphorus-containing polysaccharide

  • sulphur containing polysaccharide

  • simple polysaccharide


A.

Nitrogen containing polysaccharide

Macromolecule chitin is a complex polysaccharide containing amino sugars and chemically modified sugars (e.g., glucosamine, N -acetylgalactosamine, etc.) Polysaccharides are long carbohydrates molecules of monosaccharide units joined together by glycosidic bonds. They have general fromula (Cx(H2O)y.

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5.

The essential chemical components of many coenzymes are

  • proteins 

  • nuclei acids

  • carbohydrates

  • vitamins


D.

vitamins

Essential chemical components of many coenzymes are vitamins, e.g., coenzyme Nicotinamide Adeninne Dinucleotide (NAD) acid NADP contain the vitamin niacin Proteins, nucleic acids and carbohydrates are not enzymatic biomolecules.

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6.

Select the option which is not correct with respect to enzyme action.

  • Substrate binds with enzyme as its active site

  • Addition of lot of succinate does not reverse the inhibition of succinic dehydrogenase by malonate

  • A non- competitive inhibitor binds the enzyme at asite distinct from that which binds as the substrate

  • Malonate is a competitive inhibitor of succinic dehydrogenase


B.

Addition of lot of succinate does not reverse the inhibition of succinic dehydrogenase by malonate

Inhibition of succinic dehyrogenase by malonate is an example of competitive in inhibition.

Cometitive inhibition occurs when enzyme and inhibitor both have more or less similar structure are present in higher concentration.

Thus, both enzyme and inhibitor for competer for the acitve site of enzyme resulting to the decrease iin the enzymatic actively.

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7.

The amino acid, trytophan is the precussor for the synthesis of

  • thyroxine and tri-iodothryonine

  • estrogen and progesterone

  • cortisol and cortisone

  • melatonin and serotonin


D.

melatonin and serotonin

Melatonin and serotonin are derivatives of tryptophan amino acid.

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8.

Transition state structure of the substrate formed during an enzymatic reaction is

  • transient but stable

  • permanent but unstable

  • transient and unstable

  • permanent and stable


C.

transient and unstable

The substrate binds to the enzyme at its active site forming an enzyme-substrate complex. This complex formation is a transient and unstable phenomenon. very soon, the product is released from the active site. It is the fact that all other intermediate structural states are unstable. Stability is related to energy status of the molecule or the structure.

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9.

A typical fat molecule is made up of

  • One glycerol and three fatty acid molecules

  • One glycerol and one fatty acid moleule

  • Thre glycerol and three fatty acid molecules

  • Three glycerol molecules and one fatty acid molecule


A.

One glycerol and three fatty acid molecules

A typical fat molecule is a triglyceride formed by the esterification of one glycerol and three fatty acid molecules.

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10.

Which of the following biomolecules does have a phosphodiester bond?

  • Fatty acids in a diglyceride

  • Monosaccharides in a polysaccharide

  • Amino acids in a polypeptide

  • Nucleic acids in a nucleotide


D.

Nucleic acids in a nucleotide

Phosphodiester bond is in responsible for linking nucleotides in nucleic acid (DNA and RNA).

927 Views