Title Ex-3 Qs+Ans+sol.(Biomolecules).pdf ✅

30 BIOMOLECULES EXERCISE – 3: Advance Objective Questions The Cellular Pool 1. Fill in the blanks. Element % Weight of Earth’s crust Human body C ...a... 18.5 O ...b... 65.0 S 0.03 ...c... Si ...d... Negligible (a) a-46.6, b-27.7, c-0.03, d-0.3 (b) a-0.03, b-46.6, c-0.3, d-27.7 (c) a-0.3, b-27.7, c-0.03, d-46.6 (d) a-0.3, b-46.6, c-0.03, d-27.7 Ans. (b) Sol. Option (b) is correct as carbon, oxygen, and silicon make up 0.03%, 46.6%, and 27.7% weight of the Earth’s crust whereas sulphur makes up 0.3% of the human body. In the earth’s crust, carbon is found in sedimentary rock, oxygen is present in compound form as oxides ores of many elements, silicon is found in its ores and sand. In the human body, sulphur is found in structural proteins, metabolic enzymes, etc. Analysis of Chemical Composition 2. Read the following statements and find out the incorrect statement. (a) All the elements present in the sample of the earth’s crust are also present in a sample of living tissue (b) Relative abundance of carbon and hydrogen with respect to other elements is higher in earth’s crust than in any living organisms (c) During chemical analysis, trichloroacetic acid (Cl3CCOOH) is used (d) All of the above Ans. (b) Sol. Statement (b) wrong as carbon and hydrogen are present more abundantly in the human body than in the Earth’s crust. Carbon is an essential element in the structural components of the body tissues while hydrogen in its ionic form is important in the acid- base balance of the body. Chemical analysis for organic compounds is performed by using trichloroacetic acid which precipitates the biomacromolecules as the retentate, while the smaller and acid-soluble molecules (micro molecules) make up the filtrate. Primary and Secondary Metabolites 3. Match Column-I with Column-II and select the correct option from the codes given below. Column-I (Category) Column-II (Secondary metabolites) A . Pigments (i) Concanavalin A B . Terpenoids (ii) Monoterpenes, diterpenes C . Alkaloids (iii) Morphine, codeine D . Lectins (iv) Carotenoids, anthocyanins (a) A-(iv), B-(ii), C-(iii), D-(i) (b) A-(iv), B-(iii), C-(ii), D-(i) (c) A-(i), B-(iv), C-(iii), D-(ii) (d) A-(i), B-(iii), C-(ii), D-(iv) Ans. (a) Sol. Pigments are colored substances that include carotenoids and anthocyanins. Terpenoids are cyclic hydrocarbons that include mono and diterpenes. Alkaloids are organic compounds that include morphine and codeine. These are commonly used drugs for the treatment of pain and cough respectively. Lectins are a class of carbohydrate- binding proteins and include concanavalin A. Biomacromolecules 4. Read the given statements and select the option that correctly sorts these with respect to A and B in the given flow chart.
BIOMOLECULES 31 (i) Molecular weight ranging from 18 to 800 daltons (Da) approximately (ii) Proteins, nucleic acids, polysaccharides, and lipids (iii) Contain chemicals that have a molecular weight of more than 800 Da (iv) Has monomers (v) Generally has polymers A B (a) (i), (ii), (iii) (iv), (v) (b) (ii), (iv) (i), (iii), (v) (c) (i), (iv) (ii), (iii), (v) (d) (i), (iii), (v) (ii), (iv) Ans. (c) Sol. Chemical analysis of organic compounds present in living tissue is done by grinding the living tissue in trichloroacetic acid using a mortar and a pestle to obtain a thick slurry. On streaming this through a cheesecloth or cotton, we obtain two fractions which are called the filtrate or the acid-soluble pool and the retentate or the acid-insoluble fraction. In the filtrate, molecules that weigh around 18 to 800 Daltons (Da) and monomers are included. So (i) and (iv) are included in this pool. The acid-insoluble pool or retentate contains proteins, nucleic acids, polysaccharides, and lipids. It contains polymers and chemicals that have a molecular weight of more than 800 Daltons. So, (ii), (iii) and (v) describe this pool. 5. The correct order of chemical composition of living tissues/cells in terms of percentage of the total cellular mass is (a) Nucleic acid > Proteins >H2O>Carbohydrates> lons> Lipids (b) H2O > Proteins > Nucleic acid >Carbohydrates > Lipids >lons (c) H2O > Proteins > Carbohydrates > Nucleic acid > Lipids >lons (d) Lipids >lons> Carbohydrates > H2O > Proteins of > Nucleic acid Ans. (b) Sol. The composition of a living cell with respect to the percentage of cellular mass is water 70-90%, protein 10-15%, nucleic acid 5-7%, carbohydrates 3%, lipids 2 %, ions 1%. Therefore, the order of relative abundance of chemical constituents of a living cell is H2O > protein > nucleic acid > carbohydrate > lipids > ions. Polysaccarides 6. Reducing sugars are those which can reduce 2+ Cu ions to + Cu state. On that basis which of the following can be considered as a non-reducing sugar? (a) Sucrose (b) Maltose (c) Glucose (d) Fructose Ans. (a) Sol. Sucrose is a non-reducing sugar. It is a disaccharide composed of glucose and fructose units. In this glycosidic bond formation, the reducing groups of glucose and fructose units are involved. Due to the unavailability of free reducing groups on either side, sucrose is unable to reduce 2+ Cu into + Cu and therefore, is a non-reducing sugar. Other remaining sugars (Glucose, fructose, and maltose) are reducing sugars. 7. Study the given statements and select the correct answer. (i) Cellulose is a homopolymer of glucose. (ii) Inulin is a polymer of fructose (iii) Starch gives blue color and glycogen gives a red color with iodine solution. (iv) Cellulose gives no color with iodine solution. (a) Statements (i), (ii) and (iii) are correct (b) Statements (i), (ii) and (iv) are correct (c) Statements (ii) and (iii) are correct (d) All statements are correct. Ans. (d)
32 BIOMOLECULES Sol. Statement (i) is correct as cellulose is a linear polymer of glucose. Statement (ii) is correct as inulin is a polymer of fructose. Statement (iii) is also correct as amylose due to its helical structure, gives deep blue color with iodine while glycogen gives a red color with iodine. Hence, all the given statements are correct. 8. Read the given statements. (i) Fructose is the sweetest sugar. (ii) Glycine is the simplest amino acid. (iii) Lactose is a disaccharide composed of one molecule each of glucose and galactose. (iv) Cellulose is an unbranched chain of glucose molecules linked by -1, 4-glycosidic bond. Which of the given statements are correct? (a) (i) and (ii) (b) (iii) and (iv) (c) (i), (ii) and (iii) (d) (i), (ii), (iii) and (iv) Ans. (d) Sol. -Fructose is also known as the fruit sugar and is a monosaccharide. It is a 6-carbon molecule. -Glycine is the simplest amino acid as it contains hydrogen in the side chain. -Lactose is a disaccharide which means it has two molecules of the same or different monosaccharide units. On hydrolysis, lactose produces glucose and galactose. -Cellulose is a polysaccharide and an important constituent of the cell wall it is made up of D glucose units linked by beta 1-4 glycosidic linkage. So, the correct option is (i), (ii), (iii) and (iv). 9. Assertion: The exoskeleton of arthropods is made up of a complex polysaccharide called chitin. Reason: Plant cell walls are made up of cellulose. (a) If both assertion and reason are true and reason is the correct explanation of assertion. (b) If both assertion and reason are true but reason is not the correct explanation of assertion. (c) If assertion is true but reason is false. (d) If both assertion and reason are false. Ans. (b) Sol. Polysaccharides are complex carbohydrates that are formed by the polymerization of a large number of monosaccharide monomers. The exoskeleton of arthropods is made up of a complex polysaccharide called chitin. These complex polysaccharides are heteropolymers. Plant cell walls are made up of cellulose. Paper made from plant pulp and cotton fibre is cellulose. Cellulose is a homopolysaccharide. Amio Acids 10. Which of the following is the correct match? Acidic amino acid Basic amino acid Neutral amino acid (a) Glutamic acid Lysine Valine (b) Lysine Valine Glutamic acid (c) Glutamic acid Valine Lysine (d) Lysine Glutamic acid Valine Ans. (a) Sol. Glutamic acid, lysine, valine are amino acids that have one carboxyl group and one amine group along with a side chain. On the basis of different side chains, these are divided into a variety of categories: -Acidic amino acids are the ones that have carboxyl groups in their side chain. E.g., Glutamic acid. -Basic amino acids are the ones that have NH2 groups in their side chain. E.g., Lysine. -Neutral amino acids are the ones that have no functional groups in their side chain. E.g., Valine. 11. Which of the following statements about amino acid is incorrect? (a) Essential amino acids are not synthesized in the body, therefore have to be provided in the diet. (b) Leucine, isoleucine, lysine, valine are essential amino acids. (c) Cysteine and methionine are sulfur-containing amino acids. (d) Lysine and arginine are acidic amino acids. Ans. (d) Sol. On the basis of a group of amino acids, they are divided into a variety of types like simple amino acids, sulfur-containing amino acids, etc. Sulphur containing amino acids include cysteine and methionine. Arginine and lysine are basic amino acids that have a NH2 group as the side chain. Hence, the (d) option is incorrect.
BIOMOLECULES 33 Proteins 12. A protein is imagined as a line, the left end is represented by the first amino acid and the right end is represented by the last amino acid. The first and last acids are called as (a) N-terminal amino acid and C-terminal amino acid respectively (b) C-terminal amino acid and N-terminal amino acid respectively (c) O-terminal amino acid and C-terminal amino acid respectively (d) NH2-terminal amino acid and COOH-terminal amino acid respectively Ans. (a) Sol. A protein is imagined as a line, the left end is represented by the first amino acid and the right end is represented by the last amino acid. The first and last acids are called N-terminal amino acids and C- terminal amino acids respectively. 13. Assertion: The long protein chain is folded upon itself like a hollow ball giving rise to the tertiary structure. Reason: Tertiary structure gives a 3-dimensional view of a protein. (a) If both assertion and reason are true and reason is the correct explanation of assertion. (b) If both assertion and reason are true but reason is not the correct explanation of assertion. (c) If assertion is true but reason is false. (d) If both assertion and reason are false. Ans. (b) Sol. The primary structure of protein is the sequence of amino acids in a chain i.e., the positional information in a protein. In secondary structure, protein thread is folded in the form of a helix or in the sheet form. The long protein chain is also folded upon itself like a hollow woolen ball, giving rise to tertiary structure. This gives us a 3-dimensional view of a protein. Tertiary structure is absolutely necessary for the many biological activities of proteins. 14. Some proteins are an assembly of more than one polypeptide or subunits. The manner in which these individuals folded polypeptides are subunits are arranged with respect to each other is the architecture of a protein otherwise called the (a) Primary structure (b) Secondary structure (c) Tertiary structure (d) Quaternary structure Ans. (d) Sol. Some proteins are collections of more than one polypeptide or subunits. The way in which these individuals are folded polypeptides subunits which are arranged with respect to each other is called the quaternary structure. 15. Adult human hemoglobin consists of (a) 2 subunits (, ) (b) 2 subunits (, ) (c) 4 subunits (2, 2) (d) 3 subunits (2, 1) Ans. (c) Sol. Hemoglobin is an oxygen-containing iron molecule present in the blood. Adult hemoglobin is made up of four polypeptide subunits, 2, 2. Each of the four subunits contains heme (i.e., iron molecule) where the oxygen itself is bounded by a reversible reaction which means that a hemoglobin molecule can only transport four oxygen molecules at a time. 16. Read the following statements and find out the incorrect statement. (a) In proteins, only left-handed helices are observed. (b) 3o structure of the protein is hollow woolen ball- like. (c) Adult human hemoglobin (Hb) consists of 4 subunits. Two subunits of  -type and two subunits of -type. (d) All of the above. Amino acids Amino acid Primary protein structure is a sequence of chain of amino α-polypeptide Quaternary structure