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NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules

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Biology Solutions For Biomolecules Class 11 NCERT PDF - FREE Download

Vedantu provides Biomolecules Class 11 Biology NCERT Solutions, a key resource for students who want to navigate the concepts of Biology at the 11th-grade level. Students will learn about primary and secondary metabolites, biomacromolecules, proteins, nucleic acids, etc.

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Class 11 Biology Chapter 9 Solutions are specially designed by Vedantu Master Teachers, who ensure that they comply with the latest CBSE Class 11 Biology syllabus. Therefore, students can rely upon these NCERT Solutions to prepare for their exams.

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Access 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. What is meant by the tertiary structure of proteins?

Tertiary structure of proteins refers to the folding of a single polypeptide chain into a specific shape that determines the function of protein.


The tertiary structure of proteins


3. 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 the buyers are.

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

Glucose:


Glucose


Fructose:


Fructose


Cholesterol:


Cholesterol


Ribose:


Ribose


Deoxyribose:


Deoxyribose


Tyrosine:


Tyrosine


Tryptophan:


Tryptophan


Melatonin:


Melatonin


Adenine:


Adenine


Guanine:


Guanine


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

Industry

Compounds

Buyer

Pharmaceuticals manufacturing industries

Enzymes

Agriculture based food industries, such as companies manufacturing juices, jams, etc., research institutes, cosmetics, medicine companies, paper industry, clothing industry, etc.

The liquid glucose manufacturing industry

Liquid Glucose

Food companies, Drug and pharmaceutical companies.


4. 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.

Proteins

Therapeutic Use

  1. Insulin

Diabetes

  1. Vasopressin

Treatment of diabetes insipidus.

  1. Interleukin II

Used to prevent low platelets counts and to

decrease the requirement for blood transfusions following cancer treatments.

  1. Oxytocin

Used for inducing uterine contractions to induce labour during pregnancy.


  • 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.

5. 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.

The composition of triglyceride


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.


6. 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.


Models of biomolecules using commercially available atomic models


7. Draw the structure of the amino acid alanine.

Ans: The structure of alanine is given below.

The structure of alanine


8. 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.

9. 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

Experimental Material

Observation

Inference

(a) Urine

Yellow precipitate

The formation of yellow precipitate suggests the presence of protein in the food material

(b) Water

No precipitate


ii. A qualitative test for fats: Emulsification test

Experimental Material

Observation

Inference

(a) Sweat

Oil droplets

Formation of oil droplets

i.e., emulsification signifies the presence of fats in the provided food material.

(b) Water

No oil droplet


iii. A qualitative test for oils: Paper test

Experimental Material

Observation

Inference

(a) Food material (sample) 

Paper turns into a Translucent

Opaque paper becomes translucent which suggests the presence of fats in the food material

(b) Water

Paper gets soggy


iv. A qualitative test for starch: Iodine test

Experimental Material

Observation

Inference

  1. Fruit juices

Blue-black colour when few drops of iodine are added.

The formation of blue-black colour suggests the presence of starch in the provided food material.

  1. Water

No change in colour 


10. 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.

11. 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.

Properties of enzymes


Enzymes Work Most Excellent At Their Optimal pH


Enzymes Work Most Excellent At Their Optimal pH


Graph That Displays The Effect of pH On Enzyme Activity


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.


Class 11 Chapter 9 Biomolecules: Quick Overview of Topics Covered 

S. No

Class 11 Chapter 9 Biomolecules Topics

1

How to analyse chemical composition?

2

Primary and Secondary Metabolites

3

Biomacromolecules

4

Proteins

5

Polysaccharides

6

Nucleic Acids

7

Structure of Proteins

8

Enzymes

  • Chemical Reactions, Chemical Conversions

  • Nature of Enzyme Actions

  •  Factors Affecting Enzyme Activity 

  • Classification and Nomenclature Co-factors


Deleted Topics In Class 11 Chapter 9: Biomolecules

  • Nature of Bond Linking Monomers in a Polymer

  • Dynamic State of Body Constituents- Concept of Metabolism?

  • Metabolic Basis of Living

  • The Living State


Benefits  of Solutions for Biology Chapter 9 NCERT Biomolecules Class 11

  • Teachers of a high calibre have created the Biomolecules class 11 NCERT PDF in Class 11 Biology Chapter 9 with illustrations for easy understanding.

  • This chapter includes Various biochemical techniques, such as chromatography, electrophoresis, and spectroscopy, used to study biomolecules and their functions.

  • Complex concepts such as the structure of biomolecules are intimately linked to their function, and the structure of biomolecules helps in understanding their roles in living organisms, which is discussed concisely.

  • Nucleic acids, including DNA and RNA structured and detailed representations, help students easily grasp the concept.

  • The Biomolecules Questions and Answers PDF class 11 aims to save students valuable time so they can reap the maximum benefit in less time.

  • Biology Chapter 9 biomolecules class 11 questions and answers accurately cover the entire chapter.


Important Study Material Links for Biology Class 11 Chapter 9 Biomolecules


Conclusion

Chapter 9 NCERT biomolecules class 11 provides students with simple and detailed definitions and explanations of each concept covered in the chapter. Therefore, it is highly recommended that students download and refer to our comprehensive and expert-curated class 11 biomolecules NCERT PDF to get a gist of the chapter before the exam and to know how to answer the questions in the exam. Students can also refer to our plethora of other study resources related to this chapter, which are free on our website.


NCERT Solutions for Class 11 Biology FREE PDF | Other Chapter-wise Links

Given below are the other chapter-wise Links for the Solutions for Biology NCERT Class 11:


Related Important Links for Biology Class 11 Biology NCERT Solutions

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FAQs on NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules

1. What step-by-step approach does the NCERT Solutions for Class 11 Biology Chapter 9 follow to explain the analysis of chemical composition in biomolecules?

The NCERT Solutions for Class 11 Biology Chapter 9 use a systematic, CBSE-recommended method for analyzing chemical composition.

  • Tissue is ground and extracted using suitable solvents to obtain acid-soluble and acid-insoluble fractions.
  • The acid-soluble fraction contains small biomolecules like amino acids and sugars, while the acid-insoluble fraction has macromolecules such as proteins and nucleic acids.
  • Each category is examined further for the presence and types of biomolecules by chemical tests, chromatography, and spectroscopic analysis, ensuring clear identification aligned with CBSE 2025–26 exam methodology.

2. How does the NCERT Solutions for Biomolecules distinguish between primary and secondary metabolites?

According to the NCERT Solutions for Class 11 Biology Chapter 9, primary metabolites are molecules essential for normal growth and metabolism, such as amino acids, sugars, and nucleotides. Secondary metabolites include compounds like alkaloids and flavonoids that are not vital for basic survival but often provide ecological advantages, such as defense or signaling. Recognizing this distinction aids accurate textbook-based problem solving.

3. What is the recommended stepwise method to describe the tertiary structure of proteins in Class 11 NCERT Solutions?

NCERT Solutions recommend:

  • First, depict the polypeptide chain’s linear (primary) order of amino acids, then the localized folding (secondary structure).
  • Next, illustrate the comprehensive three-dimensional folding (tertiary structure), emphasizing bonds like hydrogen, ionic, hydrophobic interactions, and disulfide bridges.
  • This specific folding determines protein functionality, essential for exam-based diagrammatic accuracy in CBSE 2025–26.

4. How should you explain the polymeric structure of biomacromolecules when using the NCERT Solutions for Class 11 Biology Chapter 9?

The NCERT Solutions define a polymeric structure as large molecules made up of repeating monomeric units linked by covalent bonds, such as peptide, glycosidic, or phosphodiester bonds. For example, proteins consist of amino acid monomers linked by peptide bonds; polysaccharides are formed by monosaccharides linked via glycosidic bonds.

5. What are the correct steps for solving a question related to enzyme properties, as per the CBSE methodology in the NCERT Solutions?

Stepwise CBSE approach includes:

  • Begin by defining enzymes as biological catalysts, usually proteins.
  • List key properties such as substrate specificity, high efficiency, optimal temperature and pH, and sensitivity to inhibitors.
  • Explain terms like active site and note features like denaturation under extreme conditions, matching official marking schemes.

6. Why is it crucial to follow the step-by-step methods outlined in NCERT Solutions when preparing for board exams?

Following the stepwise approach ensures clear presentation, logical flow, and coverage of all points as per CBSE marking schemes. This method reduces errors, helps score maximum marks, and ensures answers meet the length and depth expected in CBSE 2025–26 board exams.

7. How does the NCERT Solutions illustrate the application of biomolecules like enzymes in industry or medicine?

The NCERT Solutions for Class 11 Biology Chapter 9 highlight that enzymes are used in:

  • Medicine (e.g., streptokinase for dissolving blood clots, insulin for diabetes management)
  • Food processing (e.g., protease in cheese making, diastase in malting)
  • Textile and leather industries (e.g., lipases for stain removal)
Detailed examples are provided to connect textbook learning with real-world applications.

8. What would happen if the three-dimensional structure of an enzyme were lost, according to NCERT Solutions?

If the three-dimensional structure of an enzyme is lost (denaturation), its active site changes shape, preventing substrate binding. As a result, the enzyme becomes inactive and can no longer catalyze biological reactions, impacting cellular metabolism.

9. How does knowledge of biomolecules help explain vital physiological processes in humans as per the Class 11 NCERT Solutions?

Understanding biomolecules is key to explaining cell structure, energy production, genetic information flow, and responses to signals. This knowledge connects chemistry concepts with biological phenomena like metabolism and disease, as emphasized in the NCERT Solutions.

10. What are some common misconceptions students have when applying NCERT Solutions to Class 11 Biomolecules, and how can they be corrected?

Common errors include confusing primary and secondary metabolites, misunderstanding enzyme-substrate specificity, and mixing up covalent bonds in different macromolecules. The NCERT Solutions address these by providing clear definitions, examples, and stepwise explanations, strengthening conceptual clarity for CBSE 2025–26 board exams.

11. In solving Class 11 Biology Chapter 9 questions, how should you describe the composition of triglycerides for maximum marks?

NCERT Solutions recommend:

  • State that a triglyceride consists of one glycerol molecule esterified with three fatty acids (which may be same or different).
  • Emphasize they are primary energy storage molecules in living organisms.
  • Differentiating between simple and mixed triglycerides adds detail as per marking scheme requirements.

12. How do the NCERT Solutions for Class 11 Biology Chapter 9 ensure answers meet the expectations of CBSE examiners?

NCERT Solutions break down each question into logical, stepwise points, incorporate labeled diagrams where required, and provide concise explanations adhering to CBSE’s latest 2025–26 syllabus and marking schemes.

13. What are the key benefits of regularly practicing with NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules?

Regular use of NCERT Solutions offers:

  • Improved conceptual understanding of biomolecules, enzymes, and their functions
  • Practice in following CBSE-approved answer formats
  • Increased confidence in diagram-based and descriptive questions
  • Reduced exam anxiety through familiarity with expected question patterns for 2025–26

14. How can students leverage the detailed explanations in CBSE Class 11 NCERT Solutions to tackle high-order application questions on enzymes or nucleic acids?

By studying stepwise explanations and real-world examples given in NCERT Solutions, students can analyze case studies, predict outcomes of molecular changes, and apply fundamental principles to unfamiliar biological scenarios. This approach develops critical thinking as required for high-order thinking skill (HOTS) questions in CBSE exams.

15. What stepwise method should you follow to perform qualitative tests for proteins, fats, and starch as outlined in the NCERT Solutions?

The recommended steps are:

  • For proteins: Use the xanthoproteic test (add nitric acid, heat – yellow color indicates proteins).
  • For fats: Apply the emulsification test (mix with water and soap – persistent emulsion forms).
  • For starch: Conduct the iodine test (blue-black color confirms starch presence).
  • Ensure all procedures and observations are described according to CBSE’s expected format.

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