Tiêu đề Ex-1 Qs+Ans+sol.(Biomolecules).pdf ✅

30 BIOMOLECULES EXERCISE – 1: Basic Objective Questions The Cellular Pool 1. Biomolecules are (a) Inorganic materials (b) Organic materials (c) All the carbon compounds obtained from living tissues (d) Only DNA and RNA Ans. (c) Sol. All the carbon compounds obtained from living tissues are called biomolecules. These organic compounds have a variety of different structures and functions. They are involved in the maintenance of the structure and metabolic processes of living organisms. They include proteins, lipids, nucleic acids, polysaccharides as well as smaller, naturally occurring ring molecules such as primary and secondary metabolites. 2. The four elements called “big-four” which make up 95% of all elements found in a living system are (a) C, H, O, N (b) C, H, O, P (c) C, H, O, S (d) C, N, O, P Ans. (a) Sol. The four elements called “big-four” which make up 95% of all elements found in a living system are carbon, hydrogen, oxygen, and nitrogen. The biological compounds that are the carbohydrates, proteins, and lipids are basically composed of carbon, hydrogen, oxygen, and nitrogen and these are present in the body in the maximum amount and so, these are also known as the big four. All these compounds are present in the structural and functional processes of a cell, which is the most basic unit of life. 3. Elements that are found more abundant in the earth’s crust than in the human body are (a) C, H, O, N, S. (b) Na, Si, Ca, Mg (c) S, Na, Ca, N (d) Si, H, Mg, O Ans. (b) Sol. These elements are sodium, silicon, calcium, and magnesium. Sodium makes up 2.8% of the total weight of the earth’s crust, silicon makes up 27.7%, Calcium 3.6% while magnesium contributes 2.1%. Sodium occurs in minerals such as Sodalite, Feldspars, and Rock salt. Silicon is a major constituent of sand. Calcium is found in minerals like Gypsum, Limestone, and Fluorite. Magnesium is commonly found in minerals like Dolomite. 4. Elements that are found more abundant in the human body than in the earth’s crust are (a) C, H, O, N, S (b) Na, Si, Ca, Mg (c) S, Na, Ca, N (d) Si, H, Mg, O Ans. (a) Sol. These elements are carbon, hydrogen, oxygen, and nitrogen. Carbon makes up 18.5% of the human body, hydrogen makes up 0.5%, oxygen 65%, and nitrogen makes up 3.3%. Carbon is an integral component of the structural tissues of the body such as muscle, bone, and cartilage. Hydrogen in its ionic form plays an important role in the acid-base balance of the body. Oxygen is present in body fluid and is also bound to hemoglobin in the RBCs of human blood. Nitrogen is an important constituent of the amino acids present in our body. Anyalysis of Chemical Composition 5. If one weighs a small amount of living tissue and dry it. Now if the tissue is fully burnt, all the carbon compounds are oxidized to gaseous form and are removed. What is the remaining called? (a) Filtrate (b) Retentate (c) Ash (d) Slurry Ans. (c) Sol. The chemical analysis of the inorganic elements present in living tissue is done by weighing a small amount of living tissue and drying it. All the water evaporates as water vapor and the remaining material gives the dry weight. Now if the tissue is fully burnt, all the carbon compounds are oxidized to gaseous carbon dioxide and are removed. What is remaining is called ash. Ash contains inorganic elements (like calcium, magnesium, etc.), and inorganic compounds like sulphates, phosphates are also present. 6. Take a living tissue, grind it in trichloroacetic acid using pestle and mortar, and then strain it, you would obtain two fractions: acid-soluble and acid- insoluble fraction. Acid insoluble fraction does not contain (a) Polysaccharides (b) Nucleic acids
BIOMOLECULES 31 (c) Lipids (d) Flavonoids and alkaloids Ans. (d) Sol. The acid-insoluble fraction has only four types of organic compounds that are proteins, nucleic acids, polysaccharides, and lipids. These classes of compounds have molecular weights in the range of ten thousand daltons and above. For this very reason, they are called biomacromolecules or macromolecules. Flavonoids and alkaloids are secondary metabolites and so, are not included under acid-insoluble fraction. 7. The inorganic compounds like sulphate, phosphate, etc., are found in (a) Acid soluble pool (b) Acid insoluble fraction (c) Both (a) and (b) (d) None of these Ans. (a) Sol. When the tissue is dried and fully burnt, all the carbon compounds are oxidized to gaseous forms - carbon dioxide and water vapor which evaporates. What remains is called ash, which contains inorganic elements. These elements form inorganic compounds like sulphate, phosphate, etc. Sulphate and phosphate are part of the chemical composition of the cytoplasm and are included in the acid-soluble pool. Primary and Secondary Metabolites 8. The compound having identifiable functions and play known roles in normal physiological processes are called (a) Primary metabolites (b) Secondary metabolites (c) Biomacromolecules (d) Polymeric substances Ans. (a) Sol. Organic compounds in living organisms are called biomolecules, these biomolecules are also called metabolites. A primary metabolite is a kind of metabolite that is directly involved in normal growth, development, and reproduction. It performs a defined physiological function in the organism (i.e., an intrinsic function). They have identifiable functions and play known roles in normal physiological processes. Examples of primary metabolites include ethanol, lactic acid, essential amino acids, etc. 9. Which of the following group represents only primary metabolites? (a) Glucose, ribose, glycine, alanine, cholesterol (b) Lectin, serine, glycerol, palmitic acid, nucleotide (c) Adenosine, nucleosides, nitrogen bases, adenylic acid, triglyceride (d) All of the above Ans. (d) Sol. Primary metabolites have identifiable functions and roles in normal physiological processes. They play a physiological (intrinsic), structural or functional role in the organism. 10. Read the following statements and find out the incorrect statement. (a) Secondary metabolites are found in plant, fungal and microbial cells and we do not understand the role of these secondary metabolites in host organisms. (b) Many secondary metabolites like rubber, drugs, spices, scents, and pigments are useful to human welfare (c) Some secondary metabolites have ecological significance. (d) Flavonoids, antibiotics, colored pigments, and starch are secondary metabolites. Ans. (d) Sol. Starch is a polysaccharide that acts as a reserve food in plants. Hence, it is a primary metabolite. When analysis of plant, fungal and microbial cells are done, there are thousands of compounds produced in plants other than primary metabolites. For example- Alkaloids, flavonoids, rubber, essential oils, antibiotics, colored pigments, scents, gums, spices, drugs, lectins, terpenoids, and toxins. These are called secondary metabolites. 11. Find the incorrect matching. (a) Essential oils- Lemon grass oil (b) Terpenoids- Monoterpenes, diterpenes (c) Polymeric substances - Rubber, gums, nucleotides (d) Pigments - Carotenoids, anthocyanins Ans. (c) Sol. Nucleotides are the basic building block of nucleic acids. They consist of a sugar molecule (ribose or deoxyribose) attached to a nitrogen-containing base and a phosphate group. Nucleotides, therefore, are monomeric units in the polymeric chain of nucleic acids. Hence, they are not polymeric substances.
32 BIOMOLECULES However, the other compounds (rubber and gums) are examples of polymers. 12. Pick out lectin from those given below. (a) Gum (b) Diterpene (c) Concanavalin (d) Curcumin Ans. (c) Sol. Lectins are secondary metabolites that include concanavalin A. Lectins are a class of carbohydrate- binding proteins that are highly specific for sugar groups of other molecules and so, they cause agglutination of particular cells. They play a role in cellular recognition and recognition of antigens and target sites of bacteria, viruses, fungi, etc. They are also found in legumes. Concanavalin A is found in the legume Canavalia ensiformis. 13. Which of the following secondary metabolites are used as drugs? (a) Abrin and ricin (b) Vinblastin and curcumin (c) Anthocyanins (d) Gums and cellulose Ans. (b) Sol. Drugs are included under secondary metabolites and include vinblastin, curcumin, etc. Vinblastin is used as an anticancer drug to treat cancers such as leukemia. Curcumin is a component of turmeric. It has medicinal properties and is commonly used for conditions like osteoarthritis, high cholesterol, liver diseases, etc. Biomacromolecules 14. Which of the following feature is common to all those compounds found in acid-soluble pool or filtrate? (a) These are called macromolecules or biomacromolecules. (b) Their molecular weight is more than ten thousand Daltons or above. (c) They have a molecular weight ranging from 18 to around 800 Da approximately. (d) Both A and B Ans. (c) Sol. Acid soluble pool or the filtrate has compounds of molecular weight ranging from 18 to around 800 Daltons (Da) approximately. These are usually referred to as micromolecules or simply biomolecules. In biology, a micromolecule refers to a molecule of relatively small size and low molecular weight. They are monomers and represent the composition of the cytoplasm. 15. Which is true about the macromolecules or biomacromolecules? (a) These are found in acid-insoluble fraction or retentate. (b) With the exception of lipids, these are polymeric substances. (c) They have molecular weights in the range of ten thousand daltons and above (exception is lipid whose molecular weight does not exceed 800 Da). (d) All of the above. Ans. (d) Sol. Statement (a) is correct with respect to biomacromolecules as they are acid-insoluble and hence do not pass through the filter or remain as retentate. Statement (b) is correct as the biomacromolecules like proteins, carbohydrates, nucleic acid are all polymeric whereas lipids are exceptions due to their oligomeric nature. Statement (c) is also correct as the molecular weight of macromolecules does range in 10,000 daltons with exception of lipids which have a molecular weight of less than 800 Da. Hence, all of the above are correct. 16. The true macromolecule (s) of the cell is/are (a) Polysaccharides (b) Polypeptides (c) Polynucleotides (d) All of the above Ans. (d) Sol. The criteria for a molecule to be a strict macromolecule is – 1. It must belong to the acid-insoluble pool. 2. It must be polymeric in nature. 3. It must have a molecular weight of more than 800 daltons. Carbohydrates (polysaccharides), proteins (polypeptides), and nucleic acids (polynucleotides) all fulfill these criteria. They are all strict bio macro-molecules. 17. Which is not a micromolecule? (a) Cellulose (b) DNA (c) Glycogen (d) None of the above Ans. (d) Sol. Biomacromolecules are proteins, carbohydrates, nucleic acids, and lipids. Cellulose and glycogen are carbohydrates (both being polymers of glucose) while DNA is a nucleic acid (polymer of
BIOMOLECULES 33 nucleotides). Therefore, all of them are macromolecules. 18. Most abundant component of cell is (a) Protein (b) Water (c) Cellulose (d) Lipid Ans. (b) Sol. Water is the most abundant component of a living cell with a composition of about 70-90% of the total cellular mass. 19. Principal organic constituent of a living being in the order of relative abundance is (a) Water (b) Protein (c) Lipid (d) DNA Ans. (b) Sol. The body consists of 10-15% protein. Therefore, proteins are the principal organic constituent of a living being. Water is the most abundant non-organic component of a living cell with a composition of about 70-90% of the total cellular mass. 20. The sum total composition of the acid-soluble and acid-insoluble fraction represents the entire composition of (a) Dead cells (b) Gene pool (c) Cellular pool (d) Gene library Ans. (c) Sol. The sum total composition of the acid-soluble and acid-insoluble fraction represents the entire composition of the cellular pool. The acid-soluble pool represents roughly the cytoplasmic composition or the micromolecules. The macromolecules from the cytoplasm and the organelles become the acid- insoluble fraction which includes the proteins, lipids, nucleic acids, and polysaccharides. Together these two groups represent the entire chemical composition of living tissues or organisms. Polysaccarides 21. How many carbon atoms are generally used in composition of monosaccharides? (a) 3 to 7 (b) 1 to 5 (c) 5 to 10 (d) 5 to 15 Ans. (a) Sol. Monosaccharides are one of the simplest sugars composed of around 3-7 carbon atoms. Some examples are glucose, fructose, etc. 22. Which one is a glucose? (a) C3H6O3 (b) C6H12O5 (c) C6H12O6 (d) C6H10O6 Ans. (c) Sol. Carbohydrates have a general chemical formula of Cx  H 2O  y . For monosaccharides, x = y. We know that glucose is a 6-carbon compound. Therefore, molecular formula C6  H  6 6 12 6 2O or C H O . 23. Which of the following options correctly identifies the structural formulae shown in figure? A B (a) Fructose Ribose (b) Glucose Deoxyribose (c) Glucose Ribose (d) Glucose Fructose Ans. (c) Sol. The structure shown in figure A is a pyranose ring consisting of 5 carbon atoms and one oxygen atom. It forms a six-membered ring. It is seen in glucose. The structure shown in figure B is ribose sugar. It belongs to a furanose ring consisting of 4 carbon atoms and one oxygen atom. 24. Recognize the figure and find out the correct matching. (a) a-glucose, b-fructose, c-lecithin (b) a-fructose, b-glucose, c-glycerol (c) a-ribose, b-glucose, c-cholesterol (d) a-glucose, b-ribose, c-cholesterol Ans. (c)