NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (2023)

NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules is an important concept in understanding the chemical composition of matter found in living entities. This chapter is categorized under the latest CBSE Syllabus 2022-23. Students who look forward to make a career in the medical field must know the fundamentals. NCERT Solutions for Class 11 includes solved solutions for all the questions appearing in the textbook, answered in the same order for the convenience of students.

Students turn frightful at the mere thought of the first examinations. But with a deep understanding of concepts, thorough revision and practice, students are assured to perform exceedingly well. Class 11 can be a crucial year, as a substantial number of questions appear in the competitive exams, therefore, analyzing and understanding concepts is inevitable. NCERT Solutions steps in right here, sufficing all the academic needs of students.

Download PDF of NCERT Solutions for Class 11 Biology Chapter 9 – Biomolecules

NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (1)
NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (2)
NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (3)
NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (4)
NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (5)
NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (6)
NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (7)
NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (8)
NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (9)
NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (10)

Access Answers to NCERT Class 11 Biology Chapter 9 – Biomolecules

1. What are macromolecules? Give examples.

Solution:

Macromolecules are the biomolecules that are formed by the polymerization of a huge number of micromolecules possessing higher molecular weight. Micromolecules are found in the colloidal state in the intercellular fluid due to their insoluble nature. Protein is a macromolecule.

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

Solution:

Glycosidic bond – The bond between the individual monosaccharides is called a glycosidic linkage. This bond is formed between two carbon atoms of two adjacent monosaccharide units.

NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (11)

Peptide bond – It is a covalent bond. The amino acids in proteins are linked to one another through peptide bonds. It is formed between when the carboxyl group (-COOH) of one amino acid interacts with amino group (-NH2 ) of the adjacent amino acid when condensed.

Formation of Peptide bond – Example

NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (12)

Phospho-diester bond – that joins successive sugar molecules in a polynucleotide. It is a strong covalent bond formed between two adjacent sugar groups and phosphate. These are the bonds that form the sugar-phosphate backbone of the nucleic acids

NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (13)

3. What is meant by tertiary structure of proteins?

Solution:

It is a structure that forms when the secondary coiled polypeptides are folded to produce a hollow, wollen ball-like structure. It is folded such that the functional side groups appear on the surface while the inactive side groups are found inside.

NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (14)

(Video) NCERT/Chapter 9/Biomolecules/Class 11/Quick Revision Series/NEET/AIIMS/2019/By Beats For Biology

4. 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.

Solution:

NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (15)
NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (16)
NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (17)

CompoundManufacturerBuyer
StarchPremier starch products private limitedResearch institutes and laundries
Liquid GlucoseImperial liquid glucoseUsed in making flavored drink and in research
Enzymes like amylase, protease, and cellulasePlanet Biotech IndiaUsed in research

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

Solution:

Positional information of a protein is called the primary structure of the protein. The first amino acid in a protein is called N-terminal amino acid, and the last amino acid in a protein is called the C-terminal amino acid.

Yes, we can connect this information to check the purity or homogeneity of a protein. On the basis of carboxyl and amino groups, amino acids can be acidic, basic and neutral. Proteins can be acidic, basic and neutral.

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

Solution:

Following are the list of proteins used as therapeutic agents.

Insulin, Oxytocin, Immunoglobin, Antidiuretic Hormone( ADH), Thrombin, Fibrinogen, Renin and streptokinases.

Some other applications are:

  • Are used as artificial sweeteners. Thaumatin is a low-calorie sweetener.
  • Proteins are used as dietary supplements to maintain health
  • They are used in creams and shampoos

7. Explain the composition of triglyceride.

Solution:

When glycerol combines with three fatty acids on each of the OH groups through ester bonds, it is known as triglyceride.

NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (18)

All the three fatty acids of triglyceride in pure fat are similar while in mixed fat, they are dissimilar.

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

(Video) 11Biology #NCERT Exercise solution#Chapter-9#Biomolecules.

Solution:

During fermentation, milk protein such as casein is denatured which transforms globular proteins into fibrous proteins. This change is responsible for the production of curd or yoghurt.

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

Solution:

Yes, Biomolecules can be represented by ball and stick model. Here bonds which hold the molecule are

indicated by sticks while the atoms are represented by balls.

The figure below is a model of D-glucose where atoms of hydrogen are indicated by green balls, oxygen atoms are represented by pink balls and carbon atoms are represented by grey balls.

NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (19)

10. Attempt titrating an amino acid against a weak base and discover the number of dissociating

(ionizable) functional groups in the amino acid.

Solution:

The pH of the amino acid is recorded, and the weak base is slowly supplemented to the amino acids while continuously noting the pH. The number of changes recorded indicates the number of ionisable functional groups –COOH in the acidic range and –NH2 in the alkaline range.

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

Solution:

The structure of Alanine is as follows:

NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules (20)

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

Solution:

Gums are heteropolysaccharides formed by different monosaccharide units associated by glycosidic bonds. On

(Video) Biomolecules - Full Chapter Explanation | Class 11 Biology Chapter 9

the other hand, fevicol is different from gums as it is made up of synthetic polymers.

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

Solution:

Qualitative test for proteins

Biuret test: Biuret test identifies the presence of proteins by turning the colour of the solution to light blue to purple.

Qualitative test for fats and oils

Grease test for oils: Certain oils give a translucent stain on blue paper. This test can be used to detect the presence of oils and fats.

Qualitative test for amino acids

Ninhydrin test:

Upon adding ninhydrin reagent to the solution, colour of the solution turns to pink, purple or blue based on the type of amino acid.

TestName of itemProcedureResultConclusion
Biuret’s testFruit juiceJuice + biuret’s reagentChange of color from light blue to purplePresence of protein
SalivaSaliva + biuret’s reagentChange of color from light blue to purplePresence of protein
SweatSweat + biuret’s reagentColour does not changeAbsence of protein
UrineDrops of urine + biuret’s reagentChange of color from light blue to purplePresence of protein
Grease testFruit juiceFew drops of juice on brown paperTranslucent spot not observedAbsence of oils and fats
SalivaFew drops of saliva on brown paperTranslucent spot not observedAbsence of oils and fats
Solubility testSweatWater added with sweatOil presenceFats or oils can be present
UrineWater added to a few drops of urineSlight oily presenceFats may or may not be present
Ninhydrin testFruit juiceJuice+ninhydrin reagent (boil for few minutes)Change of color from no color to purple, pink or bluePresence of amino acids
Salivasaliva+ninhydrin reagent (boil for few minutes)Change of color from no color to purple, pink or bluePresence of amino acids
Sweatsweat+ninhydrin reagent (boil for few minutes)No color changeAbsence of amino acids
Urineurine+ninhydrin reagent (boil for few minutes)Depending upon type of amino acid, colourless solution changes to purple, pink or blue colorPresence of amino acids

14. 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!

Solution:

Biosphere produces about 100 billion tonnes of cellulose out of 170 billion tonnes of total organic matter. Production of paper consumes about 0.5 billion tonnes of wood. Trees are also utilized for other purposes including food, medicines, timber, spices etc. An approximate estimate of 1.5 billion tonnes of food is required. Wood requirement for various purposes includes 2 billion tonnes. Therefore, it is difficult to gauge the annual consumption of plant material by man. Thus, the use of cellulose led to a great loss to the vegetation.

15. Describe the important properties of enzymes.

Solution:

Almost all the enzymes are proteins. Important properties of enzymes are as follows:

  • They have a higher molecular weight and are complex macromolecules
  • They catalyse the biochemical reactions involved in the cell, assisting in breaking down larger molecules into simpler molecules or getting together two smaller molecules to form a larger one
  • Enzymes do not initiate but accelerate a reaction
  • They affect the rate of biochemical reaction and do not influence the direction of the reaction
  • They are action-specific
  • Higher turnover of enzymes causes an increase in the efficiency of a reaction. Most of the enzymes have high turnover number.
  • Enzymes are affected by temperature. As the temperature increases, enzymatic activity decreases. Maximum activity is observed at 30-40 degree Celsius.
  • Maximum activity is observed at 6-8 pH level
  • With an increase in substrate concentration, the enzymatic velocity also increases reaching maximum velocity

NCERT Solutions for Class 11 Biology Chapter 9 – Biomolecules

NCERT Solutions for Class 11 Biology Chapter 9 – Biomolecules are categorized under Unit – 3 – Cell: Structure and Functions of the latest CBSE Syllabus 2022-23. This particular unit totals up to 15 marks as per the previous years’ question papers which approximately comes up to 21% of the total weightage of the paper.

Students can revise from previous years’ question papers to get an idea of the typology of questions that can be expected from this chapter. Apart from learning concepts, knowing how to answer is the key to score optimum marks, NCERT Solutions help students with that.

(Video) Biomolecules - 1 | NCERT Highlights | NEET 2022/23 | Garima Goel

List of subtopics covered in Chapter 9 – Biomolecules:

NumberSubtopic
9.1How to analyze chemical composition?
9.2Primary And Secondary Metabolites
9.3Biomacromolecules
9.4Proteins
9.5Polysaccharides
9.6Nucleic Acids
9.7Structure Of Proteins
9.8Nature Of Bond Linking Monomers In A Polymer
9.9Dynamic State Of Body Constituents – Concept Of Metabolism
9.10Metabolic Basis For Living
9.11The Living State
9.12Enzymes

NCERT Solutions for Class 11 Biology Chapter 9 – Biomolecules

Biomolecules include some important topics which enable students to understand the chemical composition. To be able to analyze a living tissue sample and identify a specific organic compound in higher classes, a fundamental understanding of different types of tissues, anatomy, morphology, the common site at which they are found, different functionalities they carry out, etc. are equally required to comprehend concepts.

Students thus understand different chemical reactions and their conversions, role of enzymes, nature of different enzyme actions, various factors affecting the activity of enzymes, the classification and nomenclature of different enzymes.

Key Features of NCERT Solutions for Class 11 Biology Chapter 9 – Biomolecules

  • Solutions framed by subject matter experts
  • Solutions are provided as per the expected answering pattern
  • NCERT Solutions are available for free download
  • Simple and easy to understand
  • Efficient and effective study tool

Disclaimer –

Dropped Topics –

9.8 Nature of Bond Linking Monomers in a Polymer
9.9 Dynamic State of Body Constituents—Concept of Metabolism

9.10 Metabolic Basis for Living
9.11 The Living State
Question nos 2, 3, 5, 8, 10

Frequently Asked Questions on NCERT Solutions for Class 11 Biology Chapter 9

List out the properties of enzymes covered in the Chapter 9 of NCERT Solutions for Class 11 Biology.

The properties of enzymes covered in the Chapter 9 of NCERT Solutions for Class 11 Biology are –
1. The enzymes have higher molecular weight and are complex macromolecules.
2. The biochemical reactions involved in the cell are catalysed by the enzymes, assisting in breaking down larger molecules into simpler molecules.
3. Enzymes only accelerate a reaction.
4. The rate of biochemical reaction is affected by the enzymes and does not influence the direction of the reaction.
5. Enzymes are action specific.
6. The maximum activity of enzymes is observed at 6-8 pH level.

What are the fundamental concepts I can learn from the Chapter 9 of NCERT Solutions for Class 11 Biology?

The fundamental concepts you can learn from the Chapter 9 of NCERT Solutions for Class 11 Biology are –
9.1 – How to analyze chemical composition?
9.2 – Primary And Secondary Metabolites
9.3 – Biomacromolecules
9.4 – Proteins
9.5 – Polysaccharides
9.6 – Nucleic Acids
9.7 – Structure Of Proteins
9.8 – Nature Of Bond Linking Monomers In A Polymer
9.9 – Dynamic State Of Body Constituents – Concept Of Metabolism
9.10 – Metabolic Basis For Living
9.11 – The Living State
9.12 – Enzymes

Why should you refer to the NCERT Solutions for Class 11 Biology Chapter 9?

1. The NCERT Solutions are tailored by the subject matter experts with utmost care.
2. The faculty make use of step wise answering patterns which fetch more marks to the students in the board exam.
3. PDF format solutions are available with a free download option.
4. Effective and efficient reference tool which the students can rely on.
5. The solutions are concept focused to improve conceptual knowledge among students.

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