Biomolecules sample paper

Q1. Classify the following into nitrogen bases, nucleosides and nucleotides:     Guanine   Adenosine   Thymidylic acid   Uridine

Solution

Nitrogenous Base     Nucleoside     Nucleotide     Guanine     Adenosine Uridine     Thymidylic acid        

Q2. State any one property of amino acids.

Solution

-NH₂ and -COOH groups of amino acids exhibit the ionisable nature.

Q3. What is the other name given to B-DNA?

Solution

  The other name given to B-DNA is the Watson-Crick model.

Q4. The number of base pairs present in one turn of DNA is  

• 1) 11  
• 2) 9  
• 3) 10  
• 4) 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.  

Q5. Which one is true for ATP?  

• 1) ATP is a prosthetic part of an enzyme.  
• 2) ATP is organic ions of enzyme.  
• 3) ATP is an enzyme.  
• 4) ATP is a coenzyme.  

Solution

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

Q6. The combination of apoenzyme and coenzyme produces  

• 1) Enzyme-substrate complex  
• 2) Enzyme-product complex  
• 3) Holoenzyme  
• 4) Prosthetic group  

Solution

The apoenzyme is the protein part of a conjugated enzyme, and the coenzyme is the non-protein part.     The combination of the apoenzyme and the coenzyme results in the formation of a functional enzyme which is called holoenzyme.  

Q7. Glycogen is a polymer of

• 1) Glucose
• 2) Fructose
• 3) Sucrose
• 4) Galactose

Solution

Glycogen is a polymer of glucose containing 30,000 glucose units. It is a branched chain. Glucose is joined by 1-4 α glycosidic bonds. 

Q8. Enzymes increase the rate of biochemical reaction through  

• 1) Changing equilibrium  
• 2) Forming enzyme-product complex  
• 3) Forming reactant-product complex  
• 4) Lowering activation energy  

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.  

Q9. What is the dynamic state of body constituents?

Solution

The flow of metabolites through a metabolic pathway at a definite rate and in a definite direction is called the dynamic state of body constituents.

Q10. State the number of hydrogen bonds present between the following base pairs:     Adenine and Thymine   Guanine and Cytosine  

Solution

Two hydrogen bonds – Adenine and Thymine   Three hydrogen bonds – Guanine and Cytosine  

Q11. State the common feature found in all compounds of the acid pool.

Solution

The common feature found in all compounds of the acid pool is that they have molecular weights ranging from 18 to approximately 800 dalton.

Q12. Cholesterol is

• 1) Wax
• 2) Monosaccharide
• 3) Protein
• 4) Sterol

Solution

Cholesterol is a sterol. It is a steroid present in abundance in animal tissues. Its formula is C₂₇H₄₅OH.

Q13. ATP was discovered by

• 1) Lipmann
• 2) Blackman
• 3) Karl Lohmann
• 4) Bowman

Solution

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

Q14. Define activation energy.

Solution

The difference in average energy content of a substrate from its transition state is called activation energy.

Q15. State the units used to express the concentration of biomolecules.

Solution

The units used to express the concentration of biomolecules are mols/cell and mols/litre.

Q16. Which one is correct base pairing for DNA molecule?

• 1) Adenosine-Thymine
• 2) Thymine-Uracil
• 3) Cytosine-Uracil
• 4) Thymine-Guanine

Solution

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

Q17. How is a peptide bond formed?

Solution

When the carboxyl (-COOH) group of one amino acid reacts with the (-NH2) group of the next amino acid, a molecule of water is eliminated by the process dehydration resulting in the formation of a peptide bond.

Q18. Which of the following enzymes is used in making a detergent?

• 1) Cellulase
• 2) Amylase
• 3) Peptidase
• 4) Protease

Solution

Protease helps to remove tough stains caused by protein substances. Hence, they are widely used enzymes in detergents.

Q19. Which parts of the cells form an acid-insoluble fraction?

Solution

Cytoplasm and cell organelles form the acid-insoluble fraction.  

Q20. Which is true about enzymes?

• 1) All proteins are enzymes.
• 2) All enzymes are not proteins.
• 3) All enzymes are proteins.
• 4) All enzymes are vitamins.

Solution

All enzymes are protein by nature. Amino acids join by peptide bonds and the molecule takes a three-dimensional conformation to form active sites.

Q21. Uracil is present in RNA at the place of

• 1) Guanine
• 2) Thymine
• 3) Cytosine
• 4) Adenine

Solution

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

Q22. What are saturated fatty acids?

Solution

Fatty acids which do not contain any C = C double bond are called saturated fatty acids.

Q23. Which enzyme converts glucose into alcohol?

• 1) Invertase
• 2) Diastase
• 3) Lipase
• 4) Zymase

Solution

Zymase is an enzyme complex generally formed in yeast. It catalyses the conversion of glucose to form ethanol and carbon dioxide. This conversion is called fermentation.

Q24. Give any one example of a coenzyme which acts as a cofactor.

Solution

Nicotinamide adenine dinucleotide (NAD)

Q25. Glycogen is a homopolymer made of

• 1) Ribose units
• 2) Galactose units
• 3) Glucose units
• 4) Amino acids

Solution

Glycogen is a branched chain homopolymer. It consists of about 30,000 glucose units.

Q26. Which one contains four pyrimidine bases?  

• 1) GCUAGACAA  
• 2) GATCAATGC  
• 3) UAGCGGUAA  
• 4) 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.  

Q27. One turn of the DNA double helix spans a distance of

• 1) 2.46 nm
• 2) 4.26 nm
• 3) 3.4 nm
• 4) 4.56 nm

Solution

One turn of DNA double helix is 3.4 nm long.

Q28. Which of the following are the most diverse molecules of a cell?

• 1) Carbohydrates
• 2) Mineral salts
• 3) Lipids
• 4) Proteins

Solution

Proteins are the most diverse molecules of a cell. They can have a primary, secondary, tertiary or quaternary structure. Amino acids are the building blocks of proteins, and 20 different amino acids occur in natural proteins.

Q29. Cellulose, the most important constituent of the plant cell wall, is made up of

• 1) Unbranched chain of glucose molecules linked by β, 1, 4 glycosidic bond
• 2) Branched chain of glucose molecules linked by α, 1, 6 glycosidic bond at the site of branching
• 3) Branched chain of glucose molecules linked by β, 1, 4 glycosidic bond in straight chain and α, 1, 6 glycosidic bond at the site of branching
• 4) Unbranched chain of glucose molecules linked by α, 1, 4 glycosidic bond

Solution

Cellulose is made up of glucose monomers. It is an unbranched chain of glucose molecules linked by a β,1,4 glycosidic bond. 

Q30. Feedback inhibition of enzymes is affected by which of the following:

• 1) Enzyme
• 2) End-products
• 3) Intermediate and products
• 4) Substrate

Solution

Feedback inhibition is a mechanism when the end-product of a chemical reaction results in blocking the enzyme activity of the key enzyme which resulted in its production. When the concentration of the end-product rises, it binds to the enzyme at a site different from the active site and changes the structure of the enzyme. As a result, the substrate can no longer bind to the enzyme and the reaction stops.

Q31. The enzyme which cuts DNA is

• 1) DNA lyase
• 2) Restriction endonucleases
• 3) DNA ligase
• 4) DNA polymerase

Solution

Restriction endonucleases are a group of enzymes which bring about cuts in DNA at specific sequences. They are also called biological scissors.

Q32. Give an example of anabolic pathway.  

Solution

Example of the anabolic pathway: Formation of cholesterol from acetic acid  

Q33. What are α-amino acids?

Solution

Amino acids in which the amino group and the acidic group are present as the substituents on the same α-carbon are called α-amino acids.

Q34. DNA is composed of repeating units of

• 1) Deoxyribonucleotides
• 2) Deoxyribonucleosides
• 3) Ribonucleotides
• 4) Ribonucleosides

Solution

A nucleotide is composed of a nitrogen base, pentose sugar (deoxyribose in DNA) and phosphate. Thus, DNA is said to be composed of repeating units of deoxyribonucleotides.

Q35. Conjugated proteins containing carbohydrates as a prosthetic group are known as 

• 1) Chromoproteins
• 2) Glycoproteins
• 3) Nucleoproteins
• 4) Lipoproteins

Solution

Glycoproteins are conjugated proteins with a simple or complex sugar residue at their N-terminal end. They are found in egg white, mucin, IgG and heparin.  

Q36. Expand the term RuBisCO.

Solution

RuBisCO – Ribulose bisphosphate carboxylase-oxygenase

Q37. Name the four inorganic compounds present in the acid-insoluble fraction of the slurry of living tissue and trichloroacetic acid.

Solution

Proteins, nucleic acids, polysaccharides and lipids are present in the acid-insoluble fraction of the slurry of living tissue and trichloroacetic acid.

Q38. A peptide bond is formed between which amino acids?  

• 1) 2 and 4  
• 2) 1 and 3  
• 3) 1 and 2  
• 4) 2 and 3  

Solution

A peptide bond is formed between the amino group of the first and the carboxyl group of the second amino acid.  

Q39. A homopolymer has only one type of building block called a monomer repeated ‘n’ number of times. A heteropolymer has more than one type of monomer. Proteins are heteropolymers made of amino acids. While a nucleic acid like DNA or RNA is made of only 4 types of nucleotide monomers, proteins are made of  

• 1) 3 types of monomers  
• 2) Only one type of monomer  
• 3) 20 types of monomers  
• 4) 40 types of monomers  

Solution

Amino acids joined by peptide bonds form proteins. Twenty types of amino acids are present in natural proteins.  

Q40. The protein part of a conjugated enzyme is  

• 1) Holoenzyme  
• 2) Coenzyme  
• 3) Isoenzyme  
• 4) Apoenzyme  

Solution

A functional conjugated enzyme contains one protein part and the other cofactor or prosthetic group.     The protein part is called apoenzyme.  

Q41. Explain the effect of the concentration of substrate on the activity of enzyme.  

Solution

With an increase in the substrate concentration, the velocity of the enzyme reaction increases.     At some point, the number of enzyme molecules is lower than the number of substrate molecules.     The reaction reaches a point of saturation where there no free enzyme molecules to bind with the substrate.     Hence, the rate velocity or the rate of the reaction at the saturation state is maximum, which is V_max.   

Q42. A unit composed of sugar and nitrogen base linked by a glycosidic bond is  

• 1) Glycoside  
• 2) Nucleoside  
• 3) Nucleotide  
• 4) Purine  

Solution

A nucleoside contains a pentose sugar and a nitrogen base joined by glycosidic bonds.     A purine is an aromatic double ring compound. It contains a pyrimidine ring and an imidazole ring fused together.     A glycoside is a compound which contains a sugar molecule bound to a functional group through glycosidic bonds.     A nucleotide contains a pentose sugar, a nitrogen base and a phosphate molecule.  

Q43. Enzymes, vitamins and hormones are common in  

• 1) Enhancing oxidative metabolism  
• 2) Being proteinaceous  
• 3) Regulating metabolism  
• 4) Being synthesised in the body of organisms  

Solution

Enzymes, vitamins and hormones, all help in regulating different metabolic processes in the body.  

Q44. How many amino acids exist in the biosphere?

Solution

20 amino acids exist in the biosphere.

Q45. What is enzyme inhibition?

Solution

Enzyme inhibition is the process during which an inhibitor binds to the enzyme either on its active site or some other site and shuts off the activity of the enzyme.

Q46. The simplest amino acid is

• 1) Tryptophan
• 2) Arginine
• 3) Glycine
• 4) Valine

Solution

Glycine is the simplest amino acid, with hydrogen as its R group.

Q47. The bacterial cell wall is formed of

• 1) Peptidoglycan
• 2) Cellulose
• 3) Both 1 and 2 above
• 4) Glycogen
• 5) Hemicellulose

Solution

The cell wall of bacteria is mainly composed of peptidoglycan. Peptidoglycan is a heteropolymer containing polysaccharide chains. These chains are crossed linked by peptides.

Q48. What are biomacromolecules?

Solution

Molecules which are found in the acid-insoluble fraction and have molecular weights above 10,000 dalton are called biomacromolecules.

Q49. Anti-parallel strands of a DNA molecule mean that

• 1) Phosphate groups at the start of two DNA strands (poles) are in opposite position
• 2) Phosphate groups of two DNA strands at their ends share the same position
• 3) One strand turns anticlockwise
• 4) One strand turns clockwise

Solution

Anti-parallel strands of a DNA molecule mean that phosphate groups at the start of two DNA strands (poles) are in opposite position. 

Q50. Key and lock hypothesis of enzyme action was given by

• 1) Fischer
• 2) Koshland
• 3) Buchner
• 4) Kuhn

Solution

Emil Fischer suggested the lock and key hypothesis for enzyme action in 1894.

Q51. Enzymes are polymers of

• 1) Hexose sugar
• 2) Amino acids
• 3) Inorganic phosphate
• 4) Fatty acids

Solution

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

Q52. Give any two examples of amino acids.

Solution

Two examples of amino acids are proline and alanine.

Q53. Describe the chemical analysis carried out for a plant tissue.  

Solution

The tissue to be analysed is ground with trichloroacetic acid.     The thick slurry of tissue and trichloroacetic acid is then strained through cheesecloth.     Two solutions are obtained – filtrate and retentate.     The filtrate is an acid-soluble pool which contains a number of organic compounds.     Retentate is the acid-insoluble fraction of the slurry.  

Q54. The most abundant element in living beings is

• 1) Hydrogen
• 2) Carbon
• 3) Oxygen
• 4) Nitrogen

Solution

Carbon forms the backbone of all the important molecules which make up a living cell – nucleic acids, carbohydrates, fats and proteins. Thus, it is the most abundant element in living forms.

Q55. Name the vitamin present in NADP.

Solution

Niacin is present in NADP.

Q56. A segment of DNA has 120 adenine and 120 cytosine bases. The total number of nucleotides present in the segment is  

• 1) 120  
• 2) 240  
• 3) 480  
• 4) 60  

Solution

According to Chargaff’s rule, in DNA, the amount of adenine is always equal to that of thymine and the amount of guanine is always equal to that of cytosine.     A = T = 120 and C = G = 120     Thus, the total number of nucleotides in DNA is 480.  

Q57. Describe the catalytic cycle of enzyme action. Also write the symbolic equation of the formation of the enzyme-product complex.  

Solution

The catalytic cycle of an enzyme action occurs in the following steps:     The substrate binds to the active site of the enzyme.   The binding of the substrate induces a change in the shape of the enzyme molecule, and the substrate firms itself more tightly into the active site.   The active site results in the breaking of the chemical bonds of the substrate, resulting in the formation of a new enzyme-product complex.   The enzyme molecule releases the product of the reaction and becomes free again to receive the new substrate molecule.      

Q58. Which is wrong about nucleic acids?

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

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.

Q59. In the double helix model of DNA, how far is each base pair from the next base pair?

• 1) 3.4 nm
• 2) 34 nm
• 3) 2.0 nm
• 4) 0.034 nm
• 5) 0.34 nm

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.

Q60. Proteins perform many physiological functions. For example, some function as enzymes. Which one of the following represents an additional function which some proteins discharge?

• 1) Pigments conferring colour to skin
• 2) Hormones
• 3) Antibiotics
• 4) Pigments making colours of flowers

Solution

Hormones are chemical substances which are released in the body for regulation and metabolism in cells. Many hormones such as insulin and parathormone are proteinic in nature.

Q61. Name any two nucleotides.

Solution

Guanylic acid Cytidylic acid

Q62. Define biomolecules.

Solution

All the carbon compounds which are obtained from living tissues are called biomolecules.

Q63. Define inhibitor.

Solution

An inhibitor is a substance which shuts off the activity of the enzyme by binding to the active site or some other site.

Q64. Enzymes which catalyse the interconversion of optical, geometrical or positional isomers are

• 1) Isomerases
• 2) Lyases
• 3) Ligases
• 4) Hydrolases

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.

Q65. The two strands of DNA are held together by bonds of

• 1) Nitrogen
• 2) Hydrogen
• 3) Carbon
• 4) Oxygen

Solution

Two hydrogen bonds present between adenine and thymine and three hydrogen bonds present between cytosine and guanine hold the two strands of DNA together.

Q66. Define optimum temperature.

Solution

The temperature at which an enzyme shows its highest activity is called optimum temperature.

Q67. Nucleotide, found free in the cells, is

• 1) AMP
• 2) ADP
• 3) cAMP
• 4) ATP

Solution

A triphosphate form of a nucleotide is the most stable form. ATP is a nucleotide which can be found free, unincorporated in the cell.

Q68. Name the following: Store house of energy in plants. Molecules present in the helical portion of a starch molecule. A polysaccharide present in the exoskeleton of arthropods. Heterocyclic compound present in nucleic acids.

Solution

Store house of energy in plants – Starch Molecules present in the helical portion of a starch molecule – I₂ A polysaccharide present in the exoskeleton of arthropods – Chitin Heterocyclic compounds present in nucleic acids – Nitrogenous bases

Q69. The amino acid essential in man is

• 1) Aspartic acid
• 2) Serine
• 3) Creatinine
• 4) Phenylalanine

Solution

Phenylalanine is an essential amino acid in man. It must be ingested with food as it is important for survival and is not synthesised in the human body.

Q70. What is the active site of an enzyme?

Solution

An active site is a crevice on the enzyme molecule into which a substrate molecule fits.

Q71. Write the name of the chemical used during the chemical analysis of liver tissue.

Solution

Trichloroacetic acid is used for the chemical analysis of liver tissue.

Q72. Table sugar is

• 1) Fructose
• 2) Lactose
• 3) Glucose
• 4) Sucrose

Solution

Sucrose is commonly called table sugar. It is used as a sweetener in daily life in the form of sugar. It is a non-reducing sugar containing one fructose and one glucose molecule.

Q73. 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:  

• 1) Silicon  
• 2) Sodium  
• 3) Iron  
• 4) Magnesium  

Solution

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

Q74. Write the three types of cofactors.

Solution

Three types of cofactors are Prosthetic groups Coenzymes Metal ions

Q75. What are ribozymes?

Solution

Nucleic acids which act like enzymes are called ribozymes.

Q76. Protein synthesis in an animal cell takes place  

• 1) Only in the cytoplasm
• 2) Only on ribosomes attached to the nuclear envelope
• 3) In the cytoplasm as well as in the mitochondria
• 4) In the nucleolus as well as in the cytoplasm

Solution

Protein synthesis takes place on ribosomes which are found in the cytoplasm and mitochondria. 

Q77. Give examples of the following: Acidic amino acid Basic amino acid Aromatic amino acid

Solution

Acidic amino acid – Glutamic acid Basic amino acid – Lysine Aromatic amino acid – Phenylalanine

Q78. Name the bond which links amino acids in a polypeptide.

Solution

The peptide bond links amino acids in a polypeptide.

Q79. Nitrogen is an important component of

• 1) Carbohydrates
• 2) Proteins
• 3) Lipids
• 4) Polyphosphates

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.

Q80. What is a chemical reaction?

Solution

The process of transformation of a substance in which old bonds are broken and new bonds are formed is called a chemical reaction.

Q81. Nitrogenous bases present in DNA

• 1) Adenine, guanine, cytosine, uracil
• 2) Adenine, guanine, cytosine, thymine
• 3) Guanine, uracil
• 4) Adenine, thymine, uracil

Solution

DNA contains four types of nitrogenous bases: Two double-ringed purines – adenine and guanine Two single-ringed pyrimidines – cytosine and thymine

Q82. Define substrate.

Solution

The chemical which is converted into a product during an enzyme-catalysed reaction is called a substrate.

Q83. Vitamin B₂ is a component of coenzyme  

• 1) FMN/FAD  
• 2) NAD  
• 3) TPP  
• 4) Pyridoxal phosphate  

Solution

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

Q84. Name the protein which is most abundantly found in the biosphere.

Solution

Ribulose bisphosphate carboxylase-oxygenase (RuBisCO) is the most abundantly found in the biosphere.

Q85. When is a protein structure called a tertiary structure?  

Solution

When the long protein chain gets folded upon itself like a hollow woollen ball, the structure is called the tertiary structure of a protein.  

Q86. Hydrogen bonds present between cytosine and guanosine are  

• 1) 3  
• 2) 4  
• 3) 2  
• 4) 1  

Solution

Cytosine and guanine are joined by three hydrogen bonds.     Adenine and thymine are joined by two hydrogen bonds.  

Q87. Which of the following groups contains all polysaccharides?  

• 1) Maltose, lactose and fructose  
• 2) Glycogen, cellulose and starch  
• 3) Sucrose, glucose and fructose  
• 4) Glycogen, sucrose and maltose  

Solution

Glycogen, cellulose and starch are polysaccharides.     Sucrose, maltose and lactose are disaccharides.     Glucose and fructose are monosaccharides.  

Q88. There cannot be a living state without metabolism. Justify. OR The living state and metabolism are synonymous. Justify.

Solution

The living state is non-equilibrium steady state able to perform work. Metabolism provides the mechanism for energy. The living process is a constant effort to prevent falling into equilibrium.

Q89. Which of the following is a structural subunit of DNA?

• 1) Protein
• 2) RNA
• 3) Carbohydrate
• 4) Nucleotide

Solution

Nucleotides are structural sub-units of DNA. Nucleotides join with each other through phosphodiester bonds to form a polynucleotide.

Q90. Write one characteristic feature of prosthetic cofactors.

Solution

Prosthetic groups bind tightly with the apoenzyme.

Q91. An enzyme/protein is formed by chemically bonding together  

• 1) Amino acids  
• 2) Carbohydrates  
• 3) Lipases  
• 4) CO₂  

Solution

The amino group of one amino acid is joined to the carboxyl group of the other amino acid and forms peptide bonds. Thus, amino acids join by peptide bonds and result in the formation of proteins/enzymes.  

Q92. Give an example of a lectin.

Solution

Conconavalin A is a lectin (carbohydrate-binding protein) which is extracted from the jack-bean

Q93. Name the most abundant protein found in the animal world.

Solution

Collagen

Q94. Name the bond which links monosaccharides to form a polysaccharide.

Solution

The glycosidic bond joins monosaccharides to form a polysaccharide.

Q95. Describe the formation of a phosphodiester bond in a nucleic acid.

Solution

A phosphate bond links the 3′ carbon of one sugar of one nucleotide with the hydroxyl group of the 5′ carbon of the sugar of the succeeding nucleotide. This results in the formation of an ester bond. Because such an ester bond is formed on either side of the nucleotide, it is called a phosphodiester bond.

Q96. Name any two inorganic constituents found in the living tissue.

Solution

Magnesium and calcium carbonate

Q97. The most abundant mineral of the animal body is

• 1) Sodium
• 2) Iron
• 3) Potassium
• 4) Calcium

Solution

Calcium is the most abundant mineral of an animal body. It contributes to about 2.5% of the total elements present in a cell.

Q98. Distinguish between anabolic pathway and catabolic pathway.  

Solution

Anabolic Pathway     Catabolic Pathway     Chemical reactions in which the formation of complex structures from simpler structures occurs are anabolic pathways.   Chemical reactions in which the complex molecules are degraded into simple molecules are called catabolic pathways.   These pathways consume energy.   These pathways release energy.   Example: Formation of protein from amino acid   Example: Conversion of glucose into lactic acid  

Q99. A competitive inhibitor of succinic dehydrogenase is

• 1) Malonate
• 2) Malate
• 3) α-Ketoglutarate
• 4) Oxaloacetate

Solution

Succinate dehydrogenase oxidises succinate and forms fumarate. Malonate acts as a competitive inhibitor to succinate by competing with it for binding to the active site on the enzyme succinate dehydrogenase.

Q100. Write the names of two complex polysaccharides consisting of amino sugars.

Solution

The two complex polysaccharides consisting of amino sugars are glucosamine and N-acetyl galactosamine.

Q101. Enzymes with slightly different molecular structure but performing identical activity are

• 1) Apoenzymes
• 2) Coenzymes
• 3) Holoenzyme
• 4) Isoenzymes

Solution

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

Q102. Describe the primary structure of protein.  

Solution

The primary structure of protein gives the positional information or the information about the sequence of amino acids.     The left end of the protein chain is represented by the first amino acid (i.e. the N-terminal amino acid) and the right end is represented by the last amino acid (i.e. the C-terminal amino acid).  

Q103. Genetic engineering requires enzyme

• 1) Lipase
• 2) Restriction endonuclease
• 3) DNase
• 4) Amylase

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.

Q104. Name the following:     Polymer of fructose   Polymer of glucose   Polysaccharide containing I₂   A nucleic acid with pentose sugar  

Solution

Polymer of fructose – Inulin   Polymer of glucose – Cellulose   Polysaccharide containing I₂ – Starch   A nucleic acid with deoxyribose sugar – Deoxyribonucleic acid (DNA)  

Q105. What is the unit used to measure the concentration of hormones present in living organisms?

Solution

The unit used to measure the concentration of hormones present in living organisms is nanogram/ml.

Q106. State the functions of proteins.

Solution

Functions of proteins: Transport nutrients across the cell membrane. Example: GLUT-4 Fight against infectious agents. Example: Antibodies Work as enzyme. Example: Trypsin Act as hormones. Example: Insulin

Q107. Lipids are part of the acid-insoluble fraction, but they are not strictly macromolecules. Justify.

Solution

Lipids are low molecular weight compounds. They are present in cell membranes and other membranes of the cell. While grinding the tissue with the trichloroacetic acid, the membranes are broken into pieces and form vesicles which are not water soluble. These vesicles of the membrane fragments get separated with the acid-insoluble pool and come with the macromolecular fraction. Hence, although lipids are part of the acid-insoluble fraction, they are not strictly macromolecules.

Q108. What are proteins?

Solution

Proteins are polypeptides, i.e. macromolecules formed of a linear chain of amino acids linked to each other by peptide bonds.

Q109. Give one example of catabolic pathway.  

Solution

Example of the catabolic pathway: Degradation of glucose into lactic acid  

Q110. Define living state.

Solution

The living state is a non-equilibrium steady state to be able to perform work.

Q111. Name the polysaccharide which is found in the exoskeleton of arthropods.

Solution

Chitin

Q112. Lactose is made of

• 1) Glucose + Fructose
• 2) Glucose + Galactose
• 3) Glucose + Glucose
• 4) Fructose + Fructose

Solution

Lactose is made of glucose and galactose joined by 1 and 4 carbon atoms. Lactose is present in milk.  

Q113. A functional protein is  

• 1) Collagen  
• 2) Vitamin  
• 3) Ossein  
• 4) Enzyme  

Solution

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

Q114. End-products of the same metabolic pathway can be different in different conditions. Justify.

Solution

The end-products of the same metabolic pathway can be different in different conditions. Example: If glycolysis occurs in aerobic conditions, the end-product is pyruvic acid. If glycolysis occurs in anaerobic conditions, the end-product is lactic acid. In yeasts, during fermentation, the same process leads to the formation of ethanol.

Q115. What is the energy currency in living organisms?

Solution

Adenosine triphosphate (ATP) is the energy currency in living organisms.

Q116. Name two alkaloids and flavonoids.

Solution

Alkaloids: Morphine, codeine Flavonoids: Quercetin, apigenin

Q117. Name the following: 20 carbon atom fatty acid 16 carbon atom fatty acid

Solution

20 carbon atom fatty acid – Arachidonic acid 16 carbon atom fatty acid – Palmitic acid

Q118. Define cofactors.

Solution

Cofactors are the non-protein constituents which bind to the enzyme to make the enzyme catalytically active.

Q119. Name any two nucleosides.

Solution

Uridine Thymidine

Q120. Write two examples of the secondary metabolites for the following categories which are of commercial importance: Alkaloids Drugs

Solution

Alkaloids – Codeine, Morphine Drugs – Curcumin, Vinblastine

Q121. Give any two examples of aromatic amino acids.

Solution

Examples of aromatic amino acids are tryptophan and tyrosine.

Q122. What is the rate of a chemical or physical process? When is the rate also called velocity?

Solution

The rate of chemical or physical process is the amount of product formed per unit time. When the direction is specified, the rate is also called velocity.

Q123. Define optimum pH.

Solution

The pH at which an enzyme shows its highest activity is called its optimum pH.

Q124. Identify the following:     Protein which enables glucose to transport into cells   Intercellular ground substance  

Solution

Protein which enables glucose to transport into cells – GLUT-4   Intercellular ground substance – Collagen  

Q125. Differentiate between primary metabolites and secondary metabolites.

Solution

Primary Metabolites Secondary Metabolites Functions of primary metabolites in physiological processes are known. Functions of secondary metabolites in the human body are unclear. Examples: Amino acids, sugars Examples: Carotenoids, curcumin

Q126. Name the nucleic acid which consists of a monosaccharide pentose sugar.

Solution

Ribonucleic acid (RNA)

Q127. Write the percent weight of the following in the human body. Oxygen Nitrogen Sodium Carbon

Solution

Oxygen – 65% Nitrogen – 3.3% Sodium – 0.2% Carbon – 18.5%

Q128. State the factors affecting the activity of enzymes.

Solution

Factors affecting the activity of enzymes are as follows: Temperature pH Change in substrate concentration

Q129. One mole of glucose on metabolism liberates how many kilocalories of energy?

• 1) 80
• 2) 160
• 3) 280
• 4) 180

Solution

On metabolism, glucose produces carbon dioxide, water and some nitrogenous compounds along with the release of energy which can be used by the cells. One mole of glucose on oxidation releases 280 kilocalories of energy.

Q130. What is a nucleotide?

Solution

A nucleotide is the combination of a nitrogenous base, a pentose sugar and a phosphate group esterified with the pentose sugar.

Q131. Describe the salient features of B-DNA.  

Solution

Salient features of B-DNA are as follows:  The two strands of polynucleotides run anti-parallel.  The backbone of the double helical structure is formed by the sugar-phosphate-sugar chain.  The nitrogenous bases lie perpendicular to the backbone of the molecule. They lie on the inner side.  There is a complementary base pairing between two anti-parallel strands. Example: A pairs with T and G pairs with C.  A and T are paired by the formation of two hydrogen bonds, and G and C are paired by the formation of three hydrogen bonds.  Each strand of DNA appears like a helical staircase.  Each step of the strand is represented by a pair of bases.  At each step, the strand turns 36°.  One full turn of the strand involves 10 base pairs.  The distance between two successive sugar molecules is 3.4.  

Q132. Describe any five classes of enzymes.  

Solution

There are a total of six classes into which enzymes are categorised:     Transferases: These enzymes catalyse the transfer of a group (G) between a pair of substrates (S and S′).  Dehydrogenases (Oxidoreductases): These enzymes catalyse oxidoreduction between two substrates.

Hydrolases: These enzymes catalyse the hydrolysis of ester, ether, peptide, glycosidic linkages, C-C, C-halide and P-N bonds.   Ligases: They catalyse the linking together of two compounds. These enzymes join C-°, C-S, C-N and P-° bonds.   Isomerases: These enzymes catalyse the interconversion of optical, geometric or positional isomers.  

Q133. Explain the mechanism of enzyme inhibition.

Solution

An inhibitor usually closely resembles the substrate in its molecular structure. Due to structural resemblance, the inhibitor competes with the substrate for the substrate-binding site of the enzyme. Hence, the substrate cannot bind to the enzyme which results in a decline of enzyme action.

Q134. State the normal blood glucose concentration in a healthy individual.  

Solution

The normal blood glucose concentration in a healthy individual is 4.5-5.0 mM.  

Q135. What are unsaturated fatty acids?

Solution

Fatty acids with one or more C = C double bonds are called unsaturated fatty acids.

Q136. Define metabolic pathways.  

Solution

Metabolic pathways are a series of linked reactions through which biomolecules are converted into each other.  

Q137. Write the IUPAC name of glycerol.

Solution

The IUPAC name of glycerol is trihydroxy propane.

Q138. Give examples of any two commercial products which are cellulosic.

Solution

Two commercial cellulosic products are paper pulp and cotton fibre.

Q139. What are phospholipids?

Solution

Lipids which consist of phosphorus and phosphorylated organic compounds are called phospholipids.

Q140. Explain how metal ions activate enzyme action. Give one example.  

Solution

Metal ions form coordinate bonds with the side chains at the active site. At the same time, they form one or more coordinate bonds with the substrate. Example: Zinc acts as a cofactor for the proteolytic enzyme carboxypeptidase.