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Q1. Enzymes which catalyse the interconversion of optical, geometrical or positional isomers are

• Ligases
• Lyases
• Hydrolases
• Isomerases

Solution

Isomers are substances which have the same chemical formula but different optical, positional or geometric configuration. Isomerases catalyse the interconversion of isomeric substances by the rearrangement of molecules.

Q2. When we homogenise any tissue in an acid, the acid-soluble pool represents  

• Cytoplasm  
• Cell membrane  
• Nucleus  
• Mitochondria  

Solution

When we homogenise any tissue in an acid, the acid-soluble pool represents cytoplasm.     It contains the contents of the cytoplasm which include water, carbohydrates, nucleic acids, amino acids and dissolved salts.     Macromolecules and organelles form the acid-insoluble pool.  

Q3. Ribozyme is

• RNA with enzyme activity
• RNA without sugar
• RNA without phosphate
• RNA with extra phosphate

Solution

Ribozyme is RNA with enzyme activity. It catalyses specific biochemical reactions in a cell.

Q4. The most common monomer of carbohydrates is

• Glucose
• Fructose
• Sucrose
• Maltose

Solution

Glucose is the most common monomer of most polysaccharide carbohydrates. Starch, glycogen and cellulose are polysaccharides which are formed of glucose monomers.

Q5. Many elements are found in living organisms either free or in the form of compounds. One of the following is not found in living organisms:  

• Silicon  
• Magnesium  
• Iron  
• Sodium  

Solution

Silicon is absent or found in negligible amounts in living organisms.  

Q6. Enzymes are polymers of

• Fatty acids
• Amino acids
• Hexose sugar
• Inorganic phosphate

Solution

Enzymes are protein in nature. They are polymers of amino acids which form a three-dimensional tertiary structure.

Q7. An enzyme brings about  

• Decrease in reaction time  
• Increase in reaction time  
• Increase in activation energy  
• Reduction in activation energy  

Solution

Enzymes bring about a reduction in activation energy of a system.     It thus allows a large number of molecules to react simultaneously.  

Q8. Which of the following secondary metabolites is wrongly matched?  

• Pigments - Carotenoids, anthocyanins  
• Toxin - Abrin, ricin  
• Polymeric substances - Rubber, gums  
• Alkaloids - Lemon grass oil  

Solution

Lemon grass oil is an essential oil produced as a secondary metabolite in plants.     Alkaloids are secondary metabolites produced by plants which include morphine and codeine.  

Q9. The rate of energy metabolism is equivalent to the  

• Rate of oxygen consumption  
• Rate of carbon dioxide consumption  
• Rate of nitrogen consumption  
• Rate of hydrogen consumption  

Solution

Oxidation of carbohydrates, fats and proteins to form CO₂ and H₂O liberates energy.     These reactions are referred to as energy metabolism.     For oxidation processes, oxygen is required.     Thus, the rate of energy metabolism is equivalent to the rate of oxygen consumption.  

Q10. A nucleoside differs from a nucleotide in not having a

• Sugar
• Glucose
• Nitrogen base
• Phosphate group

Solution

A nucleoside contains a pentose sugar and a nitrogen base. When a phosphate molecule is added to a nucleoside, a nucleotide is obtained. A nucleotide contains a pentose sugar, a nitrogen base and a phosphate molecule.

Q11. Which of the following biomolecules are not strictly macromolecules?

• Lipids
• Polysaccharides
• Proteins
• Nucleic acids

Solution

Lipids form a part of the acid-insoluble fraction but have a molecular weight less than 800 dalton. Hence, lipids are biomolecules which are not strictly macromolecules.

Q12. Which one contains four pyrimidine bases?  

• GATCAATGC  
• GCUAGACAA  
• UAGCGGUAA  
• TGCCTAACG  

Solution

Adenine and guanine are purine bases.     Thymine, cytosine and uracil are pyrimidine bases.     In option A - GATCAATGC - two thymine molecules and two cytosine molecules are present.  

Q13. Enzyme amylase belongs to

• Transferases
• Hydrolases
• Isomerases
• Oxidoreductases

Solution

Amylase brings about hydrolysis of starch and results in the formation of smaller molecules of carbohydrates - maltose. Thus, amylase is a hydrolase.

Q14. Which one is correct base pairing for DNA molecule?

• Cytosine-Uracil
• Thymine-Guanine
• Adenosine-Thymine
• Thymine-Uracil

Solution

In a DNA molecule, adenosine pairs with thymine using two hydrogen bonds.

Q15. Which is wrong about nucleic acids?

• DNA is single stranded in some viruses
• RNA is double stranded occasionally
• Length of one helix is 45A° in B-DNA
• One turn of Z-DNA has 12 bases

Solution

Length of one helix or the pitch per turn of helix is 34A°, 25A° in A-DNA and 46A° in Z-model of DNA.

Q16. The number of base pairs present in one turn of DNA is  

• 9  
• 10  
• 11  
• 12  

Solution

One turn of DNA double helix is 3.4 nm long.     Each turn contains 10 base pairs.     Thus, the distance between two base pairs in DNA is 0.34 nm.  

Q17. Amino acids, as the name suggests, have both an amino group and a carboxyl group in their structure. In addition, all naturally occurring amino acids (those which are found in proteins) are called L-amino acids. From this, can you guess from which compound the simplest amino acid is made?  

• Formic acid  
• Methane  
• Phenol  
• Glycine  

Solution

The general structure of an amino acid is given below.     From this we can deduce that the simplest amino acids are derived from methane.        

Q18. Nitrogen is an important component of

• Lipids
• Carbohydrates
• Polyphosphates
• Proteins

Solution

Proteins are polymers of amino acids. Nitrogen is an important component of amino acids. Proteins differ from carbohydrates and fats in having nitrogen as a component of its structure.

Q19. ATP was discovered by

• Karl Lohmann
• Lipmann
• Bowman
• Blackman

Solution

Karl Lohmann discovered ATP in 1929. He discovered ATP in muscle cells. 

Q20. Paraffin wax is

• Ester
• Acid
• Monohydric alcohol
• Cholesterol

Solution

Paraffin wax is an ester of a long chain fatty acid and alcohol other than glycerol.

Q21. Which form of RNA has a structure resembling a clover leaf?

• hnRNA
• mRNA
• tRNA
• rRNA

Solution

tRNA has a clover leaf-like structure.

Q22. A peptide bond is formed by the process of  

• Amination  
• Dehydration  
• Rehydration  
• Deamination  

Solution

A peptide bond is formed between the amino and carboxyl groups of consecutive amino acids. The bond is formed by the removal of a water molecule. This process is called dehydration.  

Q23. A functional protein is  

• Enzyme  
• Collagen  
• Ossein  
• Vitamin  

Solution

An enzyme functions to regulate metabolism in cells. Enzymes are thus termed functional proteins.  

Q24. Among the following natural materials, the largest amount of cellulose is found in

• Wood
• Fruit pulp
• Wheat straw
• Cotton fibre

Solution

Cellulose is most abundant in cotton fibres. Cellulose makes up to 90% of the composition of cotton fibres.

Q25. The 'repeating unit' of glycogen is  

• Fructose  
• Mannose  
• Glucose  
• Galactose  

Solution

The repeating unit of glycogen is glucose. Glycogen is a branched chain polymer. It consists of about 30,000 glucose units.  

Q26. The acid insoluble fraction does not contain  

• Insulin  
• DNA  
• Glycine  
• Cellulose  

Solution

Glycine is an amino acid with a small molecular weight. It is present in the acid-soluble fraction.     Insulin, DNA and cellulose are found in the acid-insoluble fraction.  

Q27. Enzymes are basically made of

• Nucleic acids
• Proteins
• Fats
• Vitamins

Solution

Enzymes are proteins in nature. Amino acids join and form the building blocks of all proteins.

Q28. The enzyme found functional in lysosome is

• Acid phosphatase
• Basic phosphatase
• Oxidoreductase
• Lyases

Solution

Lysosomes contain hydrolytic lyases. These enzymes are capable of breaking down almost all biological polymers.

Q29. Biocatalysts were found accidently in yeast extract by  

• Sumner  
• Kuhn  
• Buchner  
• Pasteur  

Solution

Buchner accidentally found that an extract obtained from yeast extract fermented glucose exactly in the same manner as yeast.     Because the extract was obtained from living cells, it was called biocatalyst.     Later, these biocatalysts were termed enzymes.  

Q30. The turnover of biomolecules is together called  

• Catabolism  
• Metabolism  
• Anabolism  
• Bioenergetics  

Solution

Biomolecules change to some other form and are also made of some other form of biomolecules. This is called turnover of biomolecules.     Chemical reactions result in making and breaking of biomolecules. These chemical reactions together are termed metabolism.  

Q31. Coenzymes FMN and FAD are derived from vitamin

• C
• B₆
• B₁
• B₂

Solution

Coenzymes FMN and FAD are composed of flavin, ribitol sugar and phosphate molecules. Flavin is derived from riboflavin. Vitamin B₂ is also called riboflavin.

Q32. Chemical reactions require energy for

• Oxidation
• Entropy
• Activation
• Enthalpy

Solution

Energy is required for the initiation of any chemical reaction. This energy activates the molecules of substances taking part in a chemical reaction.

Q33. Genetic engineering requires enzyme

• DNase
• Amylase
• Lipase
• Restriction endonuclease

Solution

Restriction endonucleases are known as biological scissors. They are of different types. Each restriction endonuclease cuts the DNA at a specific site only, resulting in the formation of a fragment which can be used for recombination techniques.

Q34. Enzymes with slightly different molecular structure but performing identical activity are

• Holoenzyme
• Isoenzymes
• Apoenzymes
• Coenzymes

Solution

Enzymes which have minor differences in their molecular structure but perform identical catalytic activity are called isoenzymes or isozymes.

Q35. Which one is true for ATP?  

• ATP is a prosthetic part of an enzyme.  
• ATP is an enzyme.  
• ATP is organic ions of enzyme.  
• ATP is a coenzyme.  

Solution

ATP works in conjugation with many enzymes. It transfers the phosphate group to the substrate and releases energy.  

Q36. Enzymes increase the rate of biochemical reaction through  

• Lowering activation energy  
• Changing equilibrium  
• Forming enzyme-product complex  
• Forming reactant-product complex  

Solution

Enzymes increase the rate of biochemical reaction through lowering the activation energy.     By lowering the activation energy, it allows a large number of molecules to react at a time, and thus, the rate of chemical reaction increases.  

Q37. Nitrogen base + pentose sugar + phosphate group is

• Nucleoside
• Nucleic acid
• Nucleotide
• Pyrimidine base

Solution

Nitrogen base + pentose sugar + phosphate group is a nucleotide. Repeated units of a nucleotide form a DNA strand.

Q38. No cell can live without

• Chloroplasts
• Proteins
• Enzymes
• Phytochromes

Solution

Enzymes regulate metabolic processes in a cell. Thus, a cell cannot live without enzymes.

Q39. Uracil is present in RNA at the place of

• Adenine
• Guanine
• Cytosine
• Thymine

Solution

Uracil is a pyrimidine present in RNA in place of thymine in DNA.

Q40. Ester linkages occur in

• Nucleic acids
• Lipids
• Carbohydrates
• Proteins

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