Careers360 Logo
Scan and Download the App!
Search Faster,
Smarter, Better
Rated 4.2
by 1M+ students
NCERT Solutions For Class 11 Biology Chapter 9 - Biomolecules

NCERT Solutions For Class 11 Biology Chapter 9 - Biomolecules

Edited By Irshad Anwar | Updated on Jul 14, 2025 01:39 PM IST

NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules help students understand the complex biological concepts. This chapter provides essential information about the chemical compounds that form the basis of life. It includes compounds such as carbohydrates, proteins, lipids, and nucleic acids. With the help of these solutions, students can strengthen their understanding, identify and work on weak areas, and build a solid foundation in the subject of biology.

NEET Scholarship Test Kit (Class 11): Narayana | Physics Wallah Aakash | ALLEN

Browse: NEET papers with solutionsMost scoring concepts for NEET

This Story also Contains
  1. Download NCERT Solutions For Class 11 Biology: Biomolecules PDF
  2. NCERT solutions for Class 11 Biology Chapter 9(Exercise Questions)
  3. Approach to Solve Questions of Class 11 Chapter 9
  4. Important Question from Class 11 Chapter 9 Biomolecules
  5. What Extra Should Students Study Beyond the NCERT for NEET?
  6. Chapter Wise NCERT Solutions for Class 11 Biology
NCERT Solutions For Class 11 Biology Chapter 9 - Biomolecules
NCERT Solutions For Class 11 Biology Chapter 9 - Biomolecules

If students find any difficulty in understanding the concept of biomolecules, they are on the right platform. The answers are written in a simple and easy-to-read manner to help students improve their conceptual clarity and perform well in exams. Biomolecules play an important role in various biological processes necessary for growth, development, and metabolism. By doing regular practice with the NCERT Solutions, students can not only increase their knowledge in the subject of Biology but also gain confidence to perform well in the exam.

Also Read,

Download NCERT Solutions For Class 11 Biology: Biomolecules PDF

The PDF for the chapter Biomolecules can be downloaded from the link given below. It can be used offline anytime for quick revision or homework help. This makes it easier to understand complex topics like carbohydrates, proteins, and enzymes. These NCERT Solutions for Class 11 are also useful for regular study and exam preparation.

Download PDF

NCERT solutions for Class 11 Biology Chapter 9(Exercise Questions)

The complete solved exercise is given below. Each question is answered step by step to improve understanding and clarity. Studying through the Class 11 Biology Chapter 9 Biomolecules question and answer allows students to understand the structure and function of molecules clearly.

Q1. What are macromolecules? Give examples.

Answer:

The complex high molecular weight molecules separated in acid-insoluble fractions in the assistance of trichloroacetic acid are referred to as macromolecules. They are polymers of a molecular weight of 10,000 daltons and above. Proteins, carbohydrates, nucleic acids etc., are macromolecules. There are lipids in the acid-insoluble fraction too, but they are not of high molecular weight.


Q2. Illustrate a glycosidic, peptide and a phospho-diester bond.

Answer:

Glycosidic bond- This bond is formed between the 1st carbon atom of one monosaccharide and 4 carbon atoms of a neighbouring monosaccharide unit. During the formation of this bond, a water molecule is released. A representation of a glycosidic bond is as follows

Peptide bond- This is a covalent bond formed between the carboxyl group of one amino acid and the amino group of neighbouring amino acids. A water molecule is released in the formation of a peptide bond. A representation of a peptide bond is as follows

Peptide Bond

Phosphodiester bond- It refers to the phosphate-hydroxyl linkage between two nucleotides. In this bond, the phosphate attached to the hydroxyl group at the 5' carbon of the pentose sugar is in turn bonded to the hydroxyl group of the 3' carbon of the pentose sugar of the next nucleotide.

 Phosphodiester bond


Q3. What is meant by the tertiary structure of proteins?

Answer:

The three-dimensional configuration of a protein that arises from repeated coiling and folding of helical and pleated polypeptide chains is termed its tertiary structure. Through repeated folding and coiling, polar side chains remain exposed whereas non-polar amino acids are kept inside. The tertiary structure is bonded through weak bonds. The activity of a protein exists in tertiary structures.


Q4. 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.

Answer:

The structures of 10 small molecular weight biomolecules are as follows

amino acid


10 small molecular weight biomolecules


These biomolecules are manufactured in biotechnology industries.

Q5. Find out and make a list of proteins used as therapeutic agents. Find other applications of proteins (e.g., Cosmetics etc.)

Answer:

Proteins with therapeutic uses are insulin, oxytocin, ADH, thrombin, fibrinogen, renin, immunoglobulin, diastase, streptokinase etc.

Other applications of proteins are

1. As cosmetics- Protein such as casein is used in beauty creams, shampoos etc.

2. Sweeteners- Thaumatin and monellin are sweet proteins.

3. Dietary supplements- Proteins can be used as dietary supplements.

Q6. Explain the composition of triglyceride.

Answer: triglyceride

A triglyceride is a chemical formed by the esterification of three molecules of fatty acids with one molecule of trihydric alcohol called glycerol. All three fatty acids of triglyceride can be similar as in tripalmitin or dissimilar as in palmito-oleoistearin, dipalmitostearin, etc.

three molecules of fatty acids


Q7. Can you describe what happens when milk is converted into curd or yoghurt, from your understanding of proteins?

Answer:

Milk has a protein known as casein. When we mix a little curd into milk, the protein casein is coagulated by the action of lactic acid bacteria and thus milk is transformed into curd. Coagulation breaks the structure of the protein casein.

Q8. Can you attempt building models of biomolecules using commercially available atomic models (Ball and Stick models).

Answer:

Yes, we can try constructing models of biomolecules with the help of commercially purchased atomic models like ball and stick models. The stick is, in the model, taken to be a bond and balls of varying colours are taken to be atoms.

Q9. Attempt titrating an amino acid against a weak base and discover the number of dissociating ( ionizable ) functional groups in the amino acid.

Answer:

When we titrate an amino acid against a weak base, it dissociates into its functional groups i.e. -COOH (carboxylic group) and -NH (amino group)

Q10. Draw the structure of the amino acid, alanine.

Answer:

The structure of the amino acid alanine is represented below:

structure of the amino acid alanine

Q11. Find out a qualitative test for proteins, fats and oils, and amino acids and test any fruit juice, saliva, sweat and urine for them.

Answer:

One of the qualitative tests for proteins is the xanthoproteic test. When a qualitative test for protein in urine is done using the aid of the xanthoproteic test, if a yellow precipitate is formed, then it is guaranteed that there is protein in it. The qualitative test for fats is the emulsification test.

During the emulsification test, the experimental material is first treated with ethanol and then dissolved in water. The development of emulsion proves the existence of fats. The qualitative analysis for oils is the paper test. The material to be tested is placed on paper. The presence of oil is established when oil marks remain.

Q12. 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 the consumption of plant material by man annually. What a loss of vegetation!

Answer:

Paper consists of wood pulp, which is predominantly composed of cellulose. Cellulose is a polymer of glucose molecules. Approximately 85 billion tonnes of cellulose are generated every year in the biosphere. Paper production requires 0.5 billion tonnes of wood. The rise in the usage of wood has caused immense loss of vegetation.

Q13. Describe the important properties of enzymes.

Answer:

Enzymes are proteinaceous substances which are capable of catalysing chemical reactions of biological origin without themselves undergoing any change. They are commonly called biocatalysts. The properties of enzymes are as follows:

1. Enzymes are proteins by nature

2. Optimum temperature- An enzyme is active within a narrow range of temperature. The temperature at which an enzyme is most active is called the optimum temperature. The enzyme activity decreased above and below this temperature.

3. Optimum pH- Every enzyme has an optimum pH at which it is maximum active. Most of the intracellular enzymes work at neutral pH.

4. Enzymes are substrate specific, i.e. one enzyme catalyses only a particular substrate. Every enzyme has specific sites called active sites for the binding of substrate.

5. Only a small quantity of the enzyme is capable of forming the desired product

6. Enzyme activity is sensitive to certain chemicals called inhibitors or modulators.

Check the NCERT Books and NCERT Syllabus here:

Approach to Solve Questions of Class 11 Chapter 9

To answer Biomolecules questions, just follow the simple steps:

  • Study the formation of chemicals in living organisms, for example, carbon, hydrogen, and oxygen.
  • Study biomacromolecules such as proteins, nucleic acids, and polysaccharides.
  • Note down primary and secondary metabolites and their role in metabolism.
  • Visit concepts such as the formation of an enzyme, function, and determinants of enzyme activity.
  • Practice the detection of bonds from the Bimolecules class 11 NCERT PDF, such as glycosidic, peptide, and phosphodiester bonds.
  • Practice with practice problems given in the NCERT Solutions Class 11 Biology to solidify the understanding of biochemical reactions and conversions.

NCERT Solutions for Class 11: Subject-wise

Important Question from Class 11 Chapter 9 Biomolecules

This chapter explains the structure, types, and functions of essential biomolecules like carbohydrates, proteins, lipids, and nucleic acids found in living organisms.

Question: What type of bond joins monosaccharides in polysaccharides?

a. Peptide bond

b. Glycosidic bond

c. Phosphodiester bond

d. Hydrogen bond

Answer: The correct answer is option (b), Glycosidic bond

Explanation: Glycosidic bonds are the chemical connections between monosaccharide units in polysaccharides. Peptide bonds connect amino acids in proteins, phosphodiester bonds connect nucleotides in DNA and RNA, and hydrogen bonds are weaker interactions that stabilise the structure of molecules.

What Extra Should Students Study Beyond the NCERT for NEET?

Here is a table for all the important topics from the chapter:

Chapter Wise NCERT Solutions for Class 11 Biology

Below are the chapter-wise solutions:


Frequently Asked Questions (FAQs)

1. What are the different types of structures of biomacromolecules given biomolecules ncert biology?

The different types of structures of biomacromolecules given in Chapter 9 of NCERT Solutions for Class 11 Biology are: 

  • primary  
  • secondary  
  • tertiary and  
  • quaternary 
2. What are the important topics of ch 9 bio class 11?

The important topics of NCERT Solutions for Class 11 Biology Chapter 9 are: 

  • Primary and Secondary Metabolites  
  • Biomacromolecules  
  • Proteins  
  • Polysaccharides  
  • Nucleic Acids  
  • Structure of Proteins  
  • Nature of Bond Linking Monomers in a Polymer  
  • Dynamic State of Body Constituents - Concept of Metabolism  
  • Metabolic Basis for Living  
  • The Living State  
  • Enzymes 
3. What is the structure and function of nucleic acids in Class 11?

Nucleic acids (DNA and RNA) are nucleotide polymers, composed of a sugar, phosphate group, and nitrogenous base (A, T/U, G, C). DNA is double-helix, whereas RNA is typically single-stranded. They carry and transfer genetic information, with DNA coordinating protein synthesis and RNA helping in transcription and translation. Their structure allows replication, gene expression, and heredity in living things.

4. What is the role of vitamins in biomolecules?

Vitamins serve as coenzymes or coenzyme precursors, facilitating enzymatic reactions during metabolism. Vitamins assist in energy production, immune function, cell growth, and repair. Vitamins are either water-soluble (B-complex, C) or fat-soluble (A, D, E, K), with each having a unique biochemical function.

5. What are the characteristics of biomolecules?

Biomolecules possess the following features:

  • Organic in Nature – Contains primarily carbon, hydrogen, oxygen, and nitrogen.
  • Macromolecular or Micromolecular – Found in the form of small molecules (e.g., vitamins) or large polymers (e.g., proteins, nucleic acids).
  • Specific Structure and Function – Every biomolecule possesses a distinctive structure that dictates its biological function.
  • Involved in Metabolism – Take part in biochemical reactions necessary for life.

Articles

A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1)

0.34\; J

Option 2)

0.16\; J

Option 3)

1.00\; J

Option 4)

0.67\; J

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

Option 2)

 6.45×10−3 kg

Option 3)

 9.89×10−3 kg

Option 4)

12.89×10−3 kg

 

An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

Option 2)

200 \, \, J - 500 \, \, J

Option 3)

2\times 10^{5}J-3\times 10^{5}J

Option 4)

20,000 \, \, J - 50,000 \, \, J

A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)

K/2\,

Option 2)

\; K\;

Option 3)

zero\;

Option 4)

K/4

In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced

Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)

0.02

Option 2)

3.125 × 10-2

Option 3)

1.25 × 10-2

Option 4)

2.5 × 10-2

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

Option 2)

increase two fold

Option 3)

remain unchanged

Option 4)

be a function of the molecular mass of the substance.

With increase of temperature, which of these changes?

Option 1)

Molality

Option 2)

Weight fraction of solute

Option 3)

Fraction of solute present in water

Option 4)

Mole fraction.

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

Option 2)

6.023 × 1022

Option 3)

half that in 8 g He

Option 4)

558.5 × 6.023 × 1023

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

Option 2)

more than 3 but less than 6

Option 3)

more than 6 but less than 9

Option 4)

more than 9

Back to top