NCERT Solutions for Class 11 Biology Chapter 9 - Biomolecules

1. What are macromolecules? Give examples?

Ans:  Chemical compounds, which are found in the acid-insoluble fraction are called macromolecules or biomacromolecules. As suggestive of its name, its molecular weights lie above \[1000\] Dalton. Consequently, micro molecules have molecular weights of less than \[1000\] Daltons. 

Examples of macromolecules are—proteins, lipids, and carbohydrates, etc. Except for lipids, all the other macromolecules including carbohydrates, proteins, and nucleic acids are polymeric substances.

2. Illustrate a peptide, glycosidic, and phosphodiester bond.

Ans: The illustration of peptide, glycosidic and phosphodiester bonds are given below.

• Peptide Bond: Amino acids in a protein are linked by Peptide bonds. Correspondingly, the proteins are called a polypeptide. Peptide bonds are formed when the carboxyl group of one amino-acid reacts with the amino group of the next amino acid with the elimination of a water molecule. As water molecule is eliminated so the reaction is that of dehydration.
  
  

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Figure: Peptide bond

• Glycosidic Bond: Glycosidic bonds are bonds linking the individual sugar units (monosaccharides) in a disaccharide or a polysaccharide. When two sugar units join, they join with the help of a glycosidic linkage with the release of a water molecule.
  
  

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Figure: Glycosidic bond

• Phosphodiester Bond: Phosphodiester bonds link individual nucleotides in a nucleic acid. So, we say DNA (a nucleic acid) is a polynucleotide. A phosphodiester linkage is formed due to the linking of carbon of one sugar of a nucleotide with the carbon of the sugar of an adjacent nucleotide by a phosphate moiety. The bond among the phosphate and hydroxyl groups of sugar is an ester bond. It is a phosphodiester bond as there is one such ester bond on either side.
  
  

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3. Write a short note about the tertiary structure of proteins?

Ans: Tertiary structure specifies the spatial layout of amino acids that are far apart in the linear structure as well as those remains that are adjacent. The arrangement of amino acids specifies the ultimate \[3\]-D structure of any specific protein. The polypeptide chain folds spontaneously so that the majority of its hydrophobic side chains are buried in the interior, and the majority of its polar charged chains are on the surface. The tertiary structure of a protein is stabilized by hydrophobic interactions, electrostatic forces (salt bridges), and disulfide links.

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4. Find and write down structures of ten fascinating small molecular weight biomolecules. Find there is any industry that produces the compounds by isolation. Find out who are the buyers.

Ans:  The structures of ten different small molecular weight biomolecules are given below.

Glucose:

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Fructose:

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Cholesterol:

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Ribose:

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Deoxyribose:

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Tyrosine:

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Tryptophan:

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Melatonin:

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Adenine:

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Guanine:

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Many industries manufacture compounds by the process of isolation. Some examples are given below.

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

Ans: The series of amino acids, i.e., the positional information in a protein which is the first amino acid, which is second, and so on is known as the primary structure of a protein. The initial amino acid is also known as an N-terminal amino acid. The final amino acid is known as the C-terminal amino acid. 

Yes, we can relate this information to the homogeneity or purity of a protein. Based on the number of amino groups and carboxyl groups, there are acidic (e.g., glutamic acid), basic (lysine), and neutral (valine) amino acids, proteins may be acidic, basic, and neutral.

6. Find out and create a list of proteins utilized as therapeutic agents. List additional uses of proteins (e.g., cosmetics, etc.)

Ans: A list of proteins used as therapeutic agents are given below.

• Both plants and animals give the appropriate proteinaceous materials for the preparation of cosmetic items. Proteins from algae and fungi, though, are also increasingly being utilized as protein sources.

• High-protein plants most widely used as beginning material for making vegetable proteins are wheat and corn gluten, rice, soy, and oat protein concentrates, and defatted oilseeds (almond, peanuts, sunflower). Among the larger variety of vegetable proteins, soy globulins and wheat gluten are by far of the widest use. Wheat gluten (often just known as wheat protein) is a distinctive cereal protein of high elasticity when hydrated. Soy proteins are useful because of their thickening and emulsifying effects.

7. Explain the composition of triglyceride.

Ans: Triglycerides are a type of lipids found in living beings, that are synthesised due to the esterification of three fatty acids with a glycerol molecule. These are also called fats and oils based on their melting points.

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Oils have lower melting points as compared to fats. The three fatty acids may be different or the same. Therefore, they may be known as simple or mixed.

8. Can you explain what occurs when the milk is converted into yoghurt or curd, from your perception of proteins.

Ans: Milk contains a protein called casein. This protein provides milk with its characteristic white colour. It is of high nutritional value because it contains all the essential amino acids required by the man's body. The curd formation takes place as lactic acid bacteria chemically react to the casein of milk. Lactic acid bacteria present in the curd that is used as the culture, cause coagulation of milk casein and thus, convert it into curd.

9. Can you try the structure of biomolecules utilizing commercially available atomic models (Ball and stick models).

Ans: Yes, we can create models of biomolecules using commercially available atomic models.

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

Ans: Once an amino acid is titrated against a weak base. It dissociates and provides two functional groups: (i) \[{\text{ -  COOH}}\]group (carboxylic group) (ii) Amino group (\[{\text{N}}{{\text{H}}_{\text{2}}}\]).

11. Draw the structure of the amino acid alanine.

Ans: The structure of alanine is given below.

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12. What are gums made of? Is fevicol different?

Ans: Gums are made up of carbohydrates and chemically they are heteropolysaccharides. 

Fevicol is polyvinyl alcohol glue. It is different from natural gums as it is a synthetic product.

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

Ans:

i. A qualitative test for proteins: Xanthoproteic test

ii. A qualitative test for fats: Emulsification test

iii. A qualitative test for oils: Paper test

iv. A qualitative test for starch: Iodine test

14. Find out exactly how much cellulose is produced by the plants in the biosphere and then compare it to how much paper is produced by human beings and therefore, what is the use of plant material by man each year. What a loss of vegetation?

Ans: Most paper is formed from wood pulp. The major component of wood pulp is cellulose, a polymer made of several glucose molecules linked together. The cellulose molecules and their bonding to each other give the paper its properties. Nearly \[33\% \] of everything in the plant matter is cellulose. The cellulose content of wood is \[40 - 50\% \]and that of cotton is\[90\% \]. For industrial use, cellulose is mostly obtained from cotton and wood pulp. It is used primarily to produce paper and paperboard; to a smaller extent. It is converted into a large variety of derivative products like rayon and cellophane.

15. Describe the important properties of enzymes.

Ans: Enzymes are proteins that catalyse biochemical reactions in cells. So, usually, enzymes are proteins but sometimes RNA also behaves catalytically. Catalytic RNAs are called Ribozymes. Each enzyme works best at its optimum temperature. Subsequently, enzymes are proteins, they are denatured at high temperatures.

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Enzymes Work Most Excellent At Their Optimal pH

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Graph That Displays The Effect of pH On Enzyme Activity

i. With the rise in substrate concentration, the velocity of the enzymatic reaction increases at first. The reaction ultimately achieves a maximum velocity (v max) which is not exceeded by any additional increase in the concentration of the substrate. 

ii. The activity of an enzyme is also sensitive to the presence of particular chemicals (maybe modulators or inhibitors of enzyme action) that bind to the enzyme. 

iii. Enzymes are substrate-specific. Due to the three-dimensional folding of the enzyme, it forms pockets or crevices. One such pocket is called the active site. An active site of the enzyme is a crevice or a pocket at which the substrate binds.

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NCERT Solutions for Class 11 Biology Chapter 9 ‘Biomolecules’ - Benefits of Class 11 Ch 9 NCERT Solutions

Class 11 Ch 9 CBSE NCERT Solutions is easy to comprehend so students can attain higher percentages in their final exams. Students can gain the following benefits after going through the NCERT Solution of Biomolecules Class 11.

• Specialised subject teachers have formulated the Biomolecules Class 11 questions and answers for students to fetch excellent marks in their exams.

• Teachers of a high calibre have described the NCERT solutions in Class 11 Biology Chapter 9 with illustrations for easy understanding.

• The NCERT Solution of Biomolecules Class 11 aims to save students valuable time so that they can reap the maximum benefit in less time.

• Biology Class 11 NCERT solutions  Chapter 9 covers the entire chapter with accuracy.

NCERT Solutions for Class 11 Biology Chapter 9 ‘Biomolecules’  - Topics Covered in Chapter 9 Biomolecules

Following are the topics covered in the chapter.

• Analysis of chemical compounds

• Primary and secondary metabolites

• Biomacromolecules

• Proteins 

• Structure of Proteins

• Polysaccharides 

• Nucleic Acids

• Concept of Metabolism 

• Metabolic pathways

• Enzymes

Class 11 Biology Biomolecules NCERT Solutions - Contents of the Pdf 

NCERT Solutions for Class 11 Biology Chapter Biomolecules entails solutions to the questions given at the end of the chapter. Students can learn the  Class 11 Biomolecules questions and answers from the Biology Biomolecules NCERT Solutions pdf offered by Vedantu on this page. NCERT Solutions Class 11 Biology Chapter 9 Biomolecules pdf includes questions from the following topics.

Ex 9.1 - How to Analyse Chemical Composition?

Ex 9.2 - Primary and Secondary Metabolites

Ex 9.3 - Biomacromolecules

Ex 9. 4 - Proteins

Ex 9.5 - Polysaccharides

Ex 9.6 - Nucleic Acids

Ex 9.7 - Structure of Protein

Ex 9.8 - Nature of Bond Linking Monomers in a Polymer

Ex 9.9 - Dynamic State of Body Constituents - Concept of Metabolism

Ex 9.10 - Metabolic Basis of Living

Ex 9.11 - The Living State

Ex 9.12 - Enzymes

Class 11 Biology Biomolecules NCERT Solutions - Summary in Points

The Biomolecules chapter is summarised in the following pointers which are as follows:

• Biomolecules are chemical substances created by living organisms that range in size from small molecules like metabolites to huge molecules like protein and carbohydrates.

• Carbohydrates, proteins, nucleic acids, and lipids are the four classifications of macromolecules.

• Carbohydrates are polyhydroxy aldehydes or ketones, or compounds that yield these when they are hydrolyzed.

• Proteins are defined as complex polypeptides which constitute monomeric amino acids. The amino acids are arranged in a specific order. 

• Based on the structure of the amino acid polypeptide arrangement, the proteins are classified as primary, secondary, tertiary, or quaternary.

• Nucleic acids (DNA and RNA) are the genetic content. The nucleic acids are responsible for passing down the hereditary information from one filial generation to another. 

• Nucleic acids are classified into two classes: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). 

• Transcription and translation are the two key processes that are accomplished by the nucleic acids.

• Transcription is defined as the process of formation of m RNA using the genetic code.

• The translation is defined as the process of protein formation from the transcribed mRNA. 

• Lipids are organic compounds that are soluble in organic solvents but insoluble in water, are connected to fatty acids, and are used by living cells. 

• Fats, waxes, sterols, fat-soluble vitamins, mono-, di-, or triglycerides, and phospholipids are examples of lipids.

NCERT Biology Class 11 Biomolecules - Important Questions and Answers (Solved) 

1. What do you mean by Hydrolysis?

Ans. While carbohydrates are digested the glycosidic bond between sugar residue is broken with the presence of water and this is termed ‘Hydrolysis’.

2. Name one monosaccharide sugar that is found in the blood plasma of human beings.

Ans. Glucose. 

3. How does calcium help our body?

Ans. Calcium helps in making our bones and teeth strong. 

NCERT Biology Class 11 Biomolecules Weightage Marks

Students would need to attempt 70 marks in of theory and 30 marks in of practical in the examination. The latest marking scheme suggests that Biology Class 11 Chapter 9, which is a part of Unit III, will carry 12 marks for theory and four marks for practical questions excluding Practical Record and Viva Voce. The students would need to perform one minor experiment under Part A.

Preparation Tips - How Do I Study Biology in CBSE Class 11?

Below are some tips which can be referred to and studied in Biology in CBSE Class 11:

1. Study the concepts thoroughly and understand the chapters well.

2. Practice the theories with the diagrams.

3. Solve NCERT-based questions and answers.

4. Also, study the previous year’s questions and answers to know the types of questions which might come in the question paper.