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NCERT Solutions for Class 11 Biology Chapter 9 Biomolecules are made for students to learn the complex ideas of the chapter and prepare well for their final as well as entrance exams. Biomolecules are necessary for students because they give information about the chemical compounds on which life is based, namely carbohydrates, proteins, lipids, and nucleic acids. These molecules have an important role in numerous biological processes that are required for growth, development, as well as metabolism. With NCERT Solutions, students can improve their knowledge, determine and rectify weak points, and consolidate their basic knowledge in biology. Not only does it make them trained in exams, but it also lays a strong foundation for further studies.
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If it is difficult for you to understand the concept of biomolecules, you are on the right platform. The NCERT Solutions for Class 11 are written in a simple and easy-to-read manner to make students skilled in core concepts and score well in exams. The questions and their detailed answers in the chapter are prepared by subject matter experts in sync with the updated CBSE syllabus.
Students can download the solutions from below:
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The complete solved exercise is given below:
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
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 pentose sugar is in turn bonded to the hydroxyl group of the 3' carbon of the pentose sugar of the next nucleotide.
3. 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.
Answer:
The structures of 10 small molecular weight biomolecules are as follows
These biomolecules are manufactured in biotechnology industries.
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.
Q7. Explain the composition of triglyceride.
Answer:
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.
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.
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.
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)
Q11. Draw the structure of the amino acid, alanine.
Answer:
The structure of the amino acid alanine is represented below:
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. The qualitative analysis for amino acids is the ninhydrin test.
Answer:
Paper consists of wood pulp which is predominantly composed of cellulose. Cellulose is a polymer of glucose molecules combined. Approximately 85 billion tonnes of cellulose is 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 in vegetation.
Q15. 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 ofthe enzyme is capable of forming the desired product
6. Enzyme activity is sensitive to certain chemicals called inhibitors or modulators.
To answer Biomolecules questions, just follow the simple steps:
Check the NCERT Books and NCERT Syllabus here:
Biomolecules falls under Unit 3 – Cell: Structure and Functions in the new syllabus of CBSE 11th standard Biology. According to old question papers, this unit has a maximum of 15 marks, which is around 21% of the total exam weightage. It is important to understand the concepts of subtopics in this chapter to obtain good marks.
If you are confused while reading Biomolecules, re-read the chapter, attempt questions yourself, and then match your responses with trusted solutions. This will not only benefit you in the school exams but also augment your preparation for competitive exams such as NEET.
NCERT Solutions for Class 11: Subject-wise
Here are some key reasons why biomolecules are important:
Importance | Explanation |
Building Blocks of Life | Biomolecules such as proteins, carbohydrates, lipids, and nucleic acids form the structural and functional basis of living organisms. |
Energy Storage and Supply | Carbohydrates and lipids provide the energy required for various biological activities. |
Genetic Information Transfer | Nucleic acids (DNA and RNA) store and transmit genetic information for growth and reproduction. |
Metabolic Functions | Enzymes, which are proteins, regulate biochemical reactions essential for life processes. |
Some questions from Biomolecules are given below:
1. Which of the following is a homopolymer?
a. Cellulose
b. Hemoglobin
c. DNA
d. RNA
Answer: a. Cellulose
Explanation: A homopolymer is a polymer consisting of one kind of monomer. Cellulose is a polysaccharide containing only glucose units and hence a homopolymer. Hemoglobin is a protein (heteropolymer), and DNA and RNA are nucleic acids that consist of varying nucleotides.
2. What type of bond joins monosaccharides in polysaccharides?
a. Peptide bond
b. Glycosidic bond
c. Phosphodiester bond
d. Hydrogen bond
Answer: 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.
3. Which of the following is the simplest amino acid?
a. Alanine
b. Tyrosine
c. Glycine
d. Asparagine
Answer: c. Glycine
Explanation: Glycine is the simplest amino acid because it possesses the smallest side chain, which consists of a single hydrogen atom. Glycine is thus exceptional among the 20 common amino acids.
4. Proteins are heteropolymers made up of how many types of monomers?
a. 20 types
b. 40 types
c. 30 types
d. Only one type
Answer: a. 20 types
Explanation: Proteins are heteropolymers since they consist of varied kinds of monomers, that is, amino acids. Proteins have 20 conventional amino acids that form the building units of proteins.
5. Which reaction is not enzyme-mediated in biological processes?
a. Glycolysis
b. Protein synthesis
c. DNA replication
d. Formation of peptide bonds in ribosomes
Answer: d. Formation of peptide bonds in ribosomes
Explanation: Although the overall process of protein synthesis is enzyme-catalyzed, the actual peptide bond formation between amino acids during translation takes place inside the ribosome, a ribonucleoprotein complex. This is catalyzed by ribozymes (catalytic RNA) contained within the ribosome, not by free enzymes. Enzymes do play a role in other processes of protein synthesis. Glycolysis, protein synthesis (overall process), and DNA replication are all enzyme-catalyzed processes.
Below mentioned are the Chapterwise solutions:
NCERT Class 11 Biology Chapter 9, "Biomolecules," describes the structure and functions of key biomolecules in easy and simple words. The chapter discusses vital concepts such as the kinds of biomolecules (carbohydrates, proteins, lipids, and nucleic acids), their functions in the body, enzyme activities, and metabolism. These solutions are by the CBSE syllabus and can be helpful for school examinations and enhancing the concepts of key points. The solutions are clearly and concisely written so that they are perfect for swift revision when exam time is around the corner. Overall, the solutions are top-notch study materials for studying biomolecules and excelling at exams.
The benefits of Chapter 9 of NCERT Solutions for Class 11 Biology are:
The different types of structures of biomacromolecules given in Chapter 9 of NCERT Solutions for Class 11 Biology are:
The important topics of NCERT Solutions for Class 11 Biology Chapter 9 are:
The properties of enzymes covered in Chapter 9 of NCERT Solutions for Class 11 Biology are:
Biomolecules are fundamental to life as they constitute cell structural elements, store and transmit genetic information and catalyze biochemical processes. They encompass carbohydrates, lipids, proteins, and nucleic acids with each having a particular function within cellular processes. Their interactions modulate metabolism, growth, and reproduction in every living organism.
Proteins are synthesized through the polymerization of amino acids with peptide bonds, as stated by NCERT. A peptide bond is established between the carboxyl (-COOH) group of a particular amino acid and the amino (-NH₂) group of another, losing a water molecule (condensation reaction). The amino acid sequence (primary structure) decides the function of the protein. Additional folding and interactions result in secondary, tertiary, and quaternary structures to give functional proteins.
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.
Enzymes function as biological catalysts by accelerating biochemical reactions without being used up. They reduce the activation energy by binding to substrates at their active site, creating an enzyme-substrate complex. This binding allows for the breaking or formation of bonds, transforming substrates to products with efficiency. Enzymes are very specific in their function, are active within a particular temperature and pH, and control metabolic pathways in living organisms.
Vitamins serve as coenzymes or coenzyme precursors, facilitating enzymatic reactions during metabolism. Vitamins assist in energy production, immune function, cell growth, and repair. Although they do not contribute to energy, their lack can result in disease and metabolic disorders. Vitamins are either water-soluble (B-complex, C) or fat-soluble (A, D, E, K), with each having a unique biochemical function.
Biomolecules possess the following features:
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