Question 1

Identify the substances having glycosidic bond and peptide bond, respectively in their structure.

Accepted Answer

Inulin is a fructan (polysaccharide of fructose). Adjacent fructose units are linked through glycosidic bond. Insulin is a protein composed of 51 amino acids. Adjacent amino acids are attached through peptide bond.

Question 2

Match the following.(a) Inhibitor of catalytic activity (i) Ricin(b) Possess peptide bonds (ii) Malonate(c) Cell wall material in fungi (iii) Chitin(d) Secondary metabolite (iv) CollagenChoose the correct option from the following

Accepted Answer

Option (1) is the correct Answer because Malonate is the competitive inhibitor of catalytic activity of succinic dehydrogenase, so (a) matches with (ii) incolumn II.Collagen is proteinaceous in nature and possesses peptide bonds, so (b) matches with (iv) in column II.Chitin is a homopolymer present in the cell wall of fungi and exoskeleton of arthropods, so, (c) matches with (iii) in column II.Abrin and Ricin are toxins, secondary metabolites, so (d) in column I matches with (i) in column II.

Question 3

Identify the basic amino acid from the following.

Accepted Answer

Option (3) is the correct Answer because lysine is a basic amino acid. Valine is a neutral amino acid.Glutamic acid is an acidic amino acid while Tyrosine is an aromatic amino acid.

Question 4

Which one of the following is the most abundant protein in the animals?

Accepted Answer

Collagen is the most abundant protein in animal world and RuBisCO is the most abundant protein in the whole of the Biosphere.

Question 5

Macro molecule chitin is :

Accepted Answer

Chitin is polymer of N-acetyl galactosamine (NAGA) so it is Nitrogen containing polysaccharide.

Question 6

Which of the following biomolecules does have a phosphodiester bond?

Accepted Answer

Phosphodiester bond is formed between two nucleotides of nucleic acid.

Question 7

Illustrate a glycosidic, peptide and a phospho-diester bond.

Accepted Answer

(i) Glycosidic bond is the type of chemical linkage between the monosaccharide units of disaccharides, oligosaccharides and polysaccharides, which is formed by the removal of a molecule of water.(ii)Peptide bonds are formed by the reaction between carboxyl (- COOH) of one amino acid and amino (- NH2) group of other amino acid with the elimination of water.(iii) In a polynucleotide chain, adjacent nucleotides are joined together by a bond called phosphodiester bond. This bond links a phosphate group and sugar group of two adjacent nucleotides by means of an oxygen bridge.

Question 8

Proteins have primary structure. If you are given a method to know which amino acid is at either of the two termini (ends) of a protein, can you connect this information to purity or homogeneity of a protein?

Accepted Answer

Yes, if we are given a method to know the sequence of proteins, we can use this information to determine the purity of a protein. It is known that an accurate sequence of a certain amino acid is very important for the functioning of a protein. If there is any change in the sequence, it would alter its structure, thereby altering the function. So by knowing the sequence of a given protein, we can determine its structure and compare it with any of the known correct protein sequences. Any change in the sequence can be linked to the purity or homogeneity of a protein.For example, a single change in the sequence of haemoglobin in P chain at the 6th position can alter the normal haemoglobin structure to an abnormal structure that can cause sickle cell anaemia.

Question 9

Find out and make a list of proteins used as therapeutic agents. Find other applications of proteins (e.g., cosmetics, etc.)

Accepted Answer

Proteins used as therapeutic agents are as follows :1. Thrombin and fibrinogen – They help in blood clotting.2. Antigen (antibody) – It helps in blood transfusion.3. Insulin – It helps in maintaining blood glucose level in the body.4. Renin – It helps in osmoregulation.Proteins are also commonly used in the manufacture of cosmetics, toxins, and as biological buffers.

Question 10

Attempt titrating an amino acid against a weak base and discover the number of dissociating (ionizable) functional groups in the amino acid.

Accepted Answer

Titrating a neutral or basic amino acid against a weak base will dissociate only one functional group, whereas titration between acidic amino acid and a weak base will dissociate two or more functional groups.

Question 11

Find out a qualitative test for proteins, fats and oils, amino acids. Test any fruit juice, saliva, sweat and urine for them.

Accepted Answer

(a) Test for proteinBiuret’s test – If Biuret’s reagent is added to the protein, then the colour of the reagent changes from light blue to purple.(b) Test for fats and oils Emulsion test - Add ethanol to a very small amount of the test substance. Shake in order to dissolve. Filter or dilute to obtain fairly clear liquid. Take another tube containing water and pour the ethanolic solution into the top. A white (milk like) emulsion indicates the presence of fats or oils.(c) Test for amino acidNinhydrin test – If Ninhydrin reagent is added to the solution, then the colourless solution changes to pink, blue, or purple, depending on the amino acid.1) Fruit juice Biuret’s test - Fruit juice + Biuret’s reagent -Colour changes from light blue to purple. Protein is present.Grease test - To a brown paper, add a few drops of fruit juice - No translucent spot. Fats and oils are absent or are in negligible amountsNinhydrin test - Fruit juice + Ninhydrin reagent + boil for 5 minutes - Colourless solution changes to pink, blue, or purple colour. Amino acids are present.2) SalivaBiuret’s test - Saliva + Biuret’s reagent - Colour changes from light blue to purple. Proteins are present.Grease test - On a brown paper, add a drop of saliva - No translucent spot. Fats/oils are absent.Ninhydrin test - Saliva + Ninhydrin reagent + boil for 5 minutes - Colourless solution changes to pink, blue, or purple colour. Amino acids are present.3) SweatBiuret’s test - Sweat + Biuret’s reagent- No colour change. Proteins are absent.Solubility test - Sweat + Water - Oily appearance - Fats/oil may be present.Ninhydrin test - Sweat + Ninhydrin reagent + boil for 5 minutes - No colour change, the solution remains colourless. Amino acids are absent.4) UrineBiuret’s test - Few drops of urine + Biuret’s reagent - Colour changes from light blue to purple- Proteins are present.Solubility test - Few drops of urine + Water - Little bit of oily appearance. Fats may or may not be present.Ninhydrin test - Few drops of urine + Ninhydrin reagent + boil for 5 minutes. Colourless solution changes to pink, blue, or purple colour depending on the type of amino acid- Amino acids are present.

Question 12

Find out how much cellulose is made by all the plants in the biosphere and compare it with how much of paper is manufactured by man and hence what is the consumption of plant material by man annually.

Accepted Answer

Approximately, 100 billion tonnes of cellulose are made per year by all the plants in the biosphere and it takes 17 full grown trees to make one ton of paper. Trees are also used to fulfill the other requirements of man such as for timber, food, medicines, etc. Hence, it is difficult to calculate the annual consumption of plant material by man.

Question 13

Describe the important properties of enzymes.

Accepted Answer

Properties of enzymes :(1) Enzymes are complex macromolecules with high molecular weight.(2) They catalyze biochemical reactions in a cell. They help in the breakdown of large molecules into smaller molecules or bring together two smaller molecules to form a larger molecule.(3) Enzymes do not start a reaction. However, they help in accelerating it.(4) Enzymes affect the rate of biochemical reaction and not the direction of the reaction.(5) Most of the enzymes have a high turnover number. Turnover number of an enzyme is the number of molecules of a substance that is acted upon by an enzyme per minute under saturated substrate concentration. High turnover number of enzymes increases the efficiency of the reaction.(6) Enzymes are specific in action.(7) Enzymatic activity decreases with increase in temperature and all enzymes show maximum activity at an optimum of 30-40oC.(8) They show maximum activity at an optimum pH of 6 – 8.(9) The velocity of enzyme increases with increase in substrate concentration and then, ultimately reaches maximum velocity.

Question 14

Which of the following is not a coenzyme?

Accepted Answer

Coenzymes are loosely attached non-protein low molecular weight thermostable organic groups, which readily separate from the apoenzyme, e. g. NAD (Nicotinamide Adenine Dinucleotide), NADP (Nicotinamide Adenine Dinucleotide Phosphate), FAD, FMN, Co-A, TPP (Thiamine Pyrophosphate), lipoic acid, etc. ATP (Adenosine Triphosphate) is the common energy currency of all cells.

Question 15

A high fever is dangerous to humans because

Accepted Answer

At high temperature, enzymes present in the body gets destroyed.

Question 16

The enzyme part, which combines with non-protein part to form a functional enzyme, is known as

Accepted Answer

Functional form of enzymes is known as holoenzyme. It consists of a proteins part known as apoenzyme and non-protein part called prosthetic group (coenzyme of a metal ion).

Question 17

Amino acids are organic compounds and are called α-amino acids. Why?

Accepted Answer

Amino acids are organic amino acids containing an amino group and an acidic group pas substituents on the same carbon, i.e., the α− carbon. Hence, they are called α-amino acids.

Question 18

Enzymes that catalyses the removal of groups from substrates by mechanism other than hydrolysis, addition of groups to double bonds are called

Accepted Answer

Lyases catalyse the breakage of specific covalent bonds and removal of groups without hydrolysis. Example histidine decarboxylase splits C− C bonds of histidine forming CO2​ and histamine.

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