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NCERT Solutions Class 11 Biology Chapter 9 - Biomolecules
NCERT Solutions for Class 11 Biology Chapter 9, Biomolecules, explain the chemical substances found in living organisms and their importance in different life processes. The chapter covers important biomolecules such as proteins, carbohydrates, lipids, and nucleic acids, along with their structures and functions. Students can also learn about the different bonds that join biomolecules and understand the role of enzymes in biological reactions.
NCERT Solutions for Class 11 Biology Chapter 9 by ALLEN provide clear explanations of important topics such as the structure of proteins, peptide and glycosidic bonds, nucleic acids, enzymes, cofactors, and enzyme activity. Students can understand the factors affecting enzyme activity and the lock-and-key and induced-fit models of enzyme action. The solutions follow the concepts covered in NCERT Class 11 Biology Chapter 9 and help students prepare for questions based on biomolecules and enzymes.
1.0NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules: Key Concepts
Class 11 Biology Chapter 9, Biomolecules, explains the chemical substances present in living organisms and their roles in maintaining life. The key concepts covered in this chapter include:
- Chemical Composition of Living Organisms: Understand the chemical composition of living and non-living matter and the separation of cellular components into acid-soluble and acid-insoluble fractions.
- Primary and Secondary Metabolites: Learn about primary metabolites involved in normal growth and physiological functions and secondary metabolites such as alkaloids, terpenoids, and pigments.
- Proteins: Study proteins as polymers of amino acids and understand their primary, secondary, tertiary, and quaternary structures.
- Polysaccharides: Understand the structure and functions of carbohydrates such as cellulose, starch, and glycogen.
- Nucleic Acids: Learn about the structure of nucleotides and nucleosides, along with the structure of DNA and RNA.
- Lipids: Study fats, oils, phospholipids, and other lipids, including their role as important components of cell membranes.
- Bonds in Biomolecules: Learn about the fundamental ties that connect biological molecules, such as peptide, glycosidic, and phosphodiester connections.
- Enzymes: Learn about enzymes as biological catalysts, the role of activation energy, and factors such as temperature, pH, and substrate concentration that affect enzyme activity.
- Mechanism of Enzyme Action: Understand the lock-and-key model and induced-fit model of enzyme action.
- Michaelis-Menten Concept: Learn how enzyme activity changes with substrate concentration and understand the basic concept of Michaelis-Menten kinetics.
- Cofactors: Study different types of cofactors, including prosthetic groups, coenzymes, and metal ions, and understand their role in enzyme activity.
2.0Detailed NCERT Textbook Solutions : Class 11 Biology Chapter 9
- What are macromolecules? Give examples. Ans. Macromolecules are large high molecular weight substances with complex molecular structure and occur in colloidal state (being insoluble) in intracellular fluid. These are formed by polymerization of large number of micromolecules. Polysaccharides, proteins and nucleic acids are few examples. Their molecular weight in the range of ten thousand daltons and above.
- What is meant by tertiary structure of proteins? Ans. The long protein chain is also folded upon itself like a hollow woolen ball, giving rise to the tertiary structure. This gives us a 3-dimensional view of a protein. Tertiary structure is absolutely necessary for the many biological activities of proteins
- Find and write down structures of 10 interesting small molecular weight biomolecules. Find if there is any industry which manufactures the compounds by isolation. Find out who are the buyers. Ans. Structures of 10 interesting small molecular weight biomolecules are as follows : These compound are manufactured commercially by isolation/extraction fermentation or chemical synthesis depend on the compound. The main buyers of these compound are food and beverage companies, pharmaceutical companies.
- Find out and make a list of proteins used as therapeutic agents. Find other applications of proteins. (eg. cosmetics etc) Ans. Proteins used as therapeutic agents are: thrombin, fibrinogen, enkephalins, antigens, antibodies, streptokinase, protein tyrosine kinase, diastase, renin, insulin, oxytocin, vasopressin etc. Proteins are also used in cosmetics, dairy industries, textile industries, research techniques, biological buffers etc.
- Explain the composition of triglycerides. Ans. Many lipids have both glycerol and fatty acids. Here the fatty acids are found esterified with glycerol. They can be then monoglycerides, diglycerides and triglycerides. These are also called fats and oils based on melting point.
- Can you attempt building models of biomolecules using commercially available atomic models (Ball and stick models). Ans. Yes, models of biomolecules can be prepared using commercially available atomic models. Ball and stick models and space filling models are 3D or spatial molecular models which serve to display the structure of chemical products and substances or biomolecules. With ball and stick models, the centers of the atoms are connected by straight lines which represent the covalent bonds. Double and triple bonds are often represented by springs which form curved connections between the balls. The bond angles and bond lengths reflect the actual relationships, while the space occupied by the atoms is either not represented at all or only denoted essentially by the relative sizes of the spheres.
- Draw the structure of the amino acid, alanine. Ans.
- What are gums made of ? Is fevicol different ? Ans. Gums are hetero-polysaccharides (poly-mers) of large number of different monosac-charide units. Yes, fevicol is a different kind of polymer. It is a synthetic sticky substance called resin which is manufactured by esteri-fication of organic compounds.
- Find out a qualitative test for proteins, fats and oils, amino acids and test any fruit juice, saliva, and urine for them. Ans. Biuret test for protein : The biuret test is a chemical test used for determining the presence of peptide bonds. In a positive test, violet colour indicates the presence of proteins. Ninhydrin test for amino acid : Ninhydrin (2,2 Dihydroxy indane-1,3-dione) is a chemical used to detect ammonia or primary and secondary amines. When reacting with these free amines, a deep blue or purple colour known as Ruhemann's purple is evolved.
Solubility test for fats and oils : A positive solubility test for fats is that the fat dissolves in lighter fluid and not in water. In this test, 5 drops of fat or oil are added in two test tubes containing 10 drops of lighter fluid and 10 drops cold water respectively. Fruit juice contains sugar so add Fehling solutions. A brick - red precipitate indicates natural sugars like glucose and fructose add Fehling's solutions. Saliva contains proteins, mineral salts, amylase etc., so it can be tested for protein and amino acids. Urine contains proteins, so it can be tested for it.
- 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. What a loss of vegetation
Ans. About 100 billion tonnes of cellulose is prepared per year by the plants of the world.
- Describe the important properties of enzymes.
Ans. The important properties of enzymes are as follows:
(i) The enzymes are generally proteins which are high molecular weight complex globular proteins. They can associate with non-protein substance for their activity. (ii) The enzymes do not start a chemical reaction but only accelerate it. They combine temporarily with the substrate molecules and are not consumed or changed permanently in the reaction which they catalyse. (iii) The enzyme controlled reactions are reversible. (iv) The enzymes are specific in action. An enzyme catalyses only a particular kind of reaction or acts on a particular substrate only. (v) The enzymes are thermolabile i.e., heat sensitive and can function best at an optimum temperature. Similarly, enzymes show maximum activity at optimum pH. (vi) The enzymes are inactivated by poisons and radiation.
3.0NCERT Class 11 Biology – Chapter-Wise Solutions & Explanations
Get NCERT Solutions for Class 11 Biology for all the chapters with solved textbook problems and clear solutions.Learn important concepts, revise each chapter, and strengthen your Biology basics for exams.
4.0Key Features of NCERT Solutions for Class 11 Biology Chapter 9
- Protein Structure: Clear explanations of the primary, secondary, tertiary, and quaternary structures of proteins and how their structure is related to their functions.
- Metabolic Processes: Simple explanations of metabolism and steady state, helping students understand how living organisms maintain continuous chemical activities.
- Enzyme Activity: Detailed explanations of enzyme action, competitive inhibition, activation energy, and factors such as temperature and pH that affect enzyme activity.
- Biomolecular Bonds: Clear explanation of the important bonds found in biomolecules, including peptide, glycosidic, and phosphodiester bonds.
- Nucleotide Structure: Diagram-based explanations of the basic structure of a nucleotide, including a sugar, nitrogenous base, and phosphate group.
- DNA Structure: Clear explanation of the Watson-Crick model of DNA and the arrangement of its components.
- Complete NCERT Exercise Coverage: Answers to the NCERT exercise questions with clear explanations based on the concepts covered in Class 11 Biology Chapter 9.
- Prepared by Expert Faculty: Prepared by ALLEN subject experts with explanations aligned with the concepts given in NCERT Class 11 Biology Chapter 9.