NCERT Solutions for Class 11 Biology Chapter 9

Download Biomolecules Class 11 Questions and Answers PDF

The PDF for the chapter Biomolecules can be downloaded from the link given below. Biomolecules Class 11 questions and answers PDF can be used offline anytime for quick revision or homework help. This makes it easier to understand complex topics like carbohydrates, proteins, and enzymes.

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Get Class 11 Biology Chapter 9 Biomolecules Question Answer (Exercise Questions)

The detailed solved explanations of all the questions given in the textbook are given below. Each question is answered step by step and follows the NCERT guidelines closely. Studying through the Class 11 Biology Chapter 9 Biomolecules question answer allows students to understand the structure clearly.

Q1. What are macromolecules? Give examples.

Answer:

The complex high molecular weight molecules separated in acid-insoluble fractions in the presence 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. 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 nonpolar amino acids are kept inside. The tertiary structure is bonded through weak bonds. The activity of a protein exists in tertiary structures.

Q3. Find and write down structures of 10 interesting small molecular-weight biomolecules. Find if there is any industry that manufactures the compounds by isolation. Find out who the buyers are.

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.

Q4. 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- Proteins such as casein are used in beauty creams, shampoos, etc.

2. Sweeteners- Thaumatin and monellin are sweet proteins.

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

Q5. Explain the composition of triglycerides.

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

Q6. 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 colors are taken to be atoms.

Q7. 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

Q8. What are gums made of? Is Fevicol different?

Answer:

Gums are made up of polysaccharides and pectins. These are the breakdown products of plant cell walls that are discharged from the wounds in the bark. Fevicol, on the other hand, is made of a sticky substance called resin. It is made of polyvinyl acetate. Gums are soluble in water, whereas resins are insoluble in water.

Q9. 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 an emulsion proves the existence of fats. The qualitative analysis for oils is the translucent spot test. The material to be tested is placed on paper. The presence of oil is established when oil marks remain.

Q10. Find out how much cellulose is made by all the plants in the biosphere and compare it with how much paper is manufactured by man, and hence what the consumption of plant material by man is 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.

Q11. Describe the important properties of enzymes.

Answer:

Enzymes are proteinaceous substances that are capable of catalyzing 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 maximally active. Most of the intracellular enzymes work at neutral pH.

4. Enzymes are substrate specific, i.e., one enzyme catalyzes 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 Biomolecules Class 11 Question Answer

To answer Biomolecules questions effectively, students can follow the simple steps given below:

Study the formation of chemicals in living organisms, for example, carbon, hydrogen, and oxygen.
Understand biomacromolecules such as proteins, nucleic acids, and polysaccharides.
Learn concepts such as the formation of an enzyme, its function, and the determinants of enzyme activity.
Note down primary and secondary metabolites and their role in metabolism. Make a comparison table using the Class 11 Biology Chapter 9 Biomolecules question answer.
Practice questions given in the NCERT Solutions for Class 11 Biology to understand the biochemical reactions.

NCERT Solutions for Class 11: Subject-wise

Important Questions of NCERT Class 11 Biology Chapter 9 Biomolecules

This chapter explains the structure and functions of biomolecules like carbohydrates, proteins, and nucleic acids. Given below are some of the important questions from this chapter, along with the answer. To score well, it is important to practice the questions given in the NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules.

Question 1: 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 stabilize the structure of molecules.

Question 2: In the zwitterionic form of tryptophan, which functional groups are present?

a. Ketonic and Aldehydic group

b. Only the Carboxylic group

c. Carboxylic and Amino group

d. Aldehyde and Amino group

Answer: The correct answer is option (c), Carboxylic and Amino group

Explanation: In the zwitterionic form of tryptophan, both the amino group and the carboxylic group are ionized. This form exists when the amino acid is in an aqueous solution at physiological pH. The molecule carries both positive and negative charges but remains electrically neutral overall.

Question 3: Identify the option that represents a typical instance of 'feedback inhibition':

a. The reaction between Cyanide and cytochrome.

b. The interaction between sulpha drugs and bacteria involved in Folic acid synthesis.

c. Allosteric inhibition of Hexokinase by Glucose 6-phosphate.

d. The reaction involves Succinic dehydrogenase and Succinic acid.

Answer: The correct answer is option (c), Allosteric inhibition of Hexokinase by Glucose 6-phosphate.

Explanation: Feedback inhibition occurs when the end product of a metabolic pathway inhibits the enzyme involved in its own synthesis. In this case, Glucose 6-phosphate inhibits Hexokinase, the enzyme that catalyzes the first step of glycolysis. This regulation prevents the unnecessary breakdown of glucose when sufficient product is already formed.

Question 4: The primary structure of a protein molecule has

a. Two ends

b. One end

c. Three ends

d. No ends

Answer: The correct answer is option (a), Two ends

Explanation: The primary structure of a protein molecule consists of a specific sequence of amino acids linked by peptide bonds. This sequence is determined by the gene encoding the protein and dictates its overall structure and function. Any change or mutation in the sequence can alter the protein's properties, potentially affecting its biological activity. The primary structure serves as the foundation for the protein's higher-order structures, including secondary, tertiary, and quaternary forms.

Question 5: Glycogen is a homopolymer made of

a. Glucose units

b. Galactose units

c. Ribose units

d. Amino acids

Answer: The correct answer is option (a), Glucose units

Explanation: Glycogen is indeed a homopolymer made of glucose units. The term "glycogen" comes from the Greek words "glyco" (meaning sweet, referring to glucose) and "gen" (meaning to produce), so it essentially means "a substance that produces glucose."

Question 6: Which of the following is an example of a nucleotide?

a. Adenosine

b. Adenine

c. Adenosine monophosphate (AMP)

d. Ribose

Answer: The correct answer is option (c), Adenosine monophosphate (AMP)

Explanation: A nucleotide is composed of a nitrogenous base, a pentose sugar, and a phosphate group. AMP contains adenine (base), ribose (sugar), and one phosphate group, fitting the definition of a complete nucleotide. Adenine alone is just a base, ribose is a sugar, and adenosine lacks the phosphate group.

Question 7: The biochemical process of converting glucose to pyruvate is called

a. Glycogenesis

b. Glycolysis

c. Gluconeogenesis

d. Glycogenolysis

Answer: The correct answer is option (b), Glycolysis

Explanation: Glycolysis is the metabolic pathway that breaks down glucose into two molecules of pyruvate, releasing energy in the form of ATP. This process occurs in the cytoplasm and is common to both aerobic and anaerobic organisms. Glycogenesis is glycogen formation, gluconeogenesis is glucose formation from non-carbohydrate sources, and glycogenolysis is glycogen breakdown.

What Students Learn from Biomolecules NCERT Solutions

Living organisms are made up of different chemical compounds that play important functions. This chapter helps students explore some of the interesting facts about these compounds.

The Biomolecules Class 11 question answer explains concepts like enzymes, their properties, and the factors affecting enzyme activity.
Students learn about carbohydrates, proteins, lipids, and nucleic acids, along with their structure and functions.
Learners understand the methods used to analyse the chemical composition of living tissues.
The Class 11 Biology Biomolecules question answer introduces metabolism and how different biomolecules participate in metabolic pathways.

Why Class 11 Biology Chapter 9 Biomolecules NCERT Solutions are Important?

The chapter Biomolecules allows students to understand the chemical composition of all living organisms and the importance of various biomolecules that are present in the human body. Different biomolecules, such as carbohydrates, proteins, lipids, and nucleic acids, are included, along with their functions and structures.

Class 11 Biology Chapter 9 Biomolecules NCERT Solutions are important because they provide explanations of concepts like enzymes, metabolism, and catalytic activity.
The solutions also help students understand the difference between different biomolecules based on their structure, function, and composition.
Different biomolecules, such as carbohydrates, proteins, lipids, and nucleic acids, are included in the solutions, along with well-labelled diagrams.
Topics of biomolecules are mainly useful for the NEET aspirants, as many questions are directly based on the biomolecules chapter in the competitive exams.

What Extra Should Students Study Beyond the NCERT for NEET?

Here is a table for all the topics from the chapter, which students have to study beyond the NCERT for NEET. Students can also go through the NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules to gain clarity.

Topics	NCERT	NEET
Definition of Biomolecules	✅	✅
Analysis of Chemical Composition in Living Tissues	✅	✅
Carbohydrates	✅	✅
Monosaccharides	❌	✅
Disaccharides	❌	✅
Polysaccharides	✅	✅
Lipids and Fatty Acids	✅	✅
TYPES OF LIPIDS - Simple Lipids	✅	✅
Types of Lipids - Compound Lipids and Derived Lipids	✅	✅
Amino Acids	✅	✅
Peptide Bond, Peptide Chain, and Proteins	✅	✅
Structure of Proteins - Primary Structure	✅	✅
Structure of Proteins - Secondary Structure	✅	✅
Structure of Proteins - Tertiary & Quaternary Structure	✅	✅
Nucleotides	✅	✅
Nucleic Acids - DNA and RNA	✅	✅
Enzymes and Their Classification	✅	✅
How Enzymes Work - Active Sites and Models	✅	✅
Enzyme Inhibition	✅	✅
Factors Affecting Enzyme Activity	✅	✅