Chapter 9: Biomolecules

Biology • Class 11

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Chapter Analysis

Intermediate16 pages • English

Quick Summary

In Chapter 9 of the Class 11 Biology textbook, biomolecules are explored, focusing on their structural diversity and functional roles in biological systems. The chapter discusses the classification of biomolecules into micromolecules and macromolecules, detailing proteins, nucleic acids, carbohydrates, and lipids. It also covers the role of enzymes as biological catalysts and the concept of primary and secondary metabolites. Biomolecules' elemental composition and their relevance in metabolic reactions are key themes explored.【4:0†source】

Key Topics

  • Chemical composition of biomolecules
  • Role of enzymes
  • Macromolecules and micromolecules
  • Primary and secondary metabolites
  • Protein structure and function
  • Nucleic acids as genetic material
  • Fatty acids and lipids
  • Classification and nomenclature of enzymes

Learning Objectives

  • Understand the classification of biomolecules based on molecular weight
  • Comprehend the structure and function of proteins and nucleic acids
  • Explore the biochemical role of enzymes as catalysts
  • Identify the differences between primary and secondary metabolites
  • Recognize the biological significance of lipids and carbohydrates
  • Analyze the conditions affecting enzyme activity

Questions in Chapter

What are macromolecules? Give examples.

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What is meant by tertiary structure of proteins?

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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.

Page 119

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

Page 119

Explain the composition of triglyceride.

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

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Draw the structure of the amino acid, alanine.

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What are gums made of? Is Fevicol different?

Page 119

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

Page 119

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!

Page 119

Describe the important properties of enzymes.

Page 119

Additional Practice Questions

Explain the role of co-factors in enzyme activity.

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Answer: Co-factors are non-protein chemical compounds that are required for the protein's biological activity to occur, acting as a 'helper molecules.' They can be organic or inorganic molecules and are often required by enzymes to bind to substrates and carry out catalysis effectively.

What is the difference between nucleotides and nucleosides?

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Answer: Nucleosides consist of a nitrogenous base attached to a sugar molecule, while nucleotides additionally have one or more phosphate groups attached to the nucleoside's sugar component.

Describe the structure of DNA and its significance.

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Answer: DNA, or deoxyribonucleic acid, is a double-helix molecule composed of two antiparallel strands of nucleotides. Each nucleotide consists of a phosphate group, a sugar molecule, and one of four nitrogenous bases. DNA carries the genetic information essential for the cell and organism function.

How are enzymes classified?

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Answer: Enzymes are classified into six categories based on the reactions they catalyze: oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. Each class is further divided into subclasses based on specific characteristics.

What factors can affect enzyme activity?

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Answer: Temperature, pH, substrate concentration, and the presence of inhibitors or activators can affect enzyme activity. Enzymes typically function optimally under specific physiological conditions, and deviations can result in decreased enzyme activity.

NCERT Exemplar

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Practice with NCERT Exemplar problems and solutions for this chapter. Exemplar problems are designed to help you master the concepts with advanced-level questions.

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