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CBSE Class 11 · Biology

Biomolecules

Official NCERT chapter from Biology (book code kebo1). ExamMaster notes are original teaching at CBSE Class 11 depth.

This lesson follows the official chapter “Biomolecules” in Biology. The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.

  • CBSE Class 11
  • Medium level
  • 8 concepts

1How to Analyse Chemical Composition?

How to analyse composition (school): dry a sample, burn or extract as taught, then name ash (inorganic) versus the carbon-rich leftover. Analysis is a split-method, not a taste. One plant-or-tissue case is enough.

A colour as “32% protein” without a method is a skip.

Figure. Grind a tissue and the extract splits by size. The acid-soluble pool holds small organics; the acid-insoluble pool holds the chains.

How it works

  1. Name dry / burn / extract as taughtThe how.
  2. Split inorganic ash versus organic leftoverThe composition.
  3. Keep it a method-wordNot a menu.

2Primary and Secondary Metabolites

Primary metabolites are the everyday building bits (sugars, amino acids as taught); secondary are extras some species make (a named alkaloid if the lesson used one). Primary versus secondary is a job-split, not “important / unimportant”.

Calling glucose secondary because it is “sweet” is a miss.

Figure. Primary metabolites sit in every living cell and do the everyday jobs. Secondary metabolites are made by some plants and fungi and are not required for that everyday life.

How it works

  1. Name everyday-build versus extra-makeThe split.
  2. Keep one school example each if askedThe cases.
  3. Refuse taste as the testA job-word.

3Biomacromolecules

Biomacromolecules: large polymers as taught — proteins, polysaccharides, nucleic acids. Macro is a size-and-chain story, not “any organic”. Amino acids and sugars are the small mates, not the macros themselves.

A glucose as a biomacromolecule is a miss.

Figure. NCERT splits the extract at about a thousand units. Amino acids sit below that cut; a protein chain sits well above it. The log bars keep both ends visible; they are order-of-magnitude, not a weighed sample.

How it works

  1. Name the polymer familyProtein, poly-sugar, or nucleic acid.
  2. Keep the monomer as the small mateTwo scales.
  3. Refuse a salt as a macromoleculeA chain-word.

4Proteins

Proteins: amino-acid chains with a job (enzyme, structure as taught). A peptide bond is the link. Protein is name-plus-job; a mute “body-building” slogan is not the heading. One haemoglobin or enzyme mention is enough.

A starch called protein because both are “food” is a miss.

Figure. Count the gaps. Four amino acids leave three peptide bonds and three water molecules. The free amino end and the free carboxyl end give the chain its N-to-C direction.

How it works

  1. Name amino-acid chain + a jobThe protein.
  2. Keep the peptide link if taughtThe bond.
  3. Refuse a slogan as the testA chain-job.

5Polysaccharides

Polysaccharides: sugar-chains — starch, glycogen, cellulose as taught. A poly-sugar is a store or a wall, not a sweet taste. Glycogen in animals, starch in plants, cellulose as wall — the school trio.

Table sugar as cellulose is a miss.

Figure. A polysaccharide is glucose after glucose, joined by glycosidic bonds. Starch and glycogen store the sugar; cellulose is the same monomer in a structural chain.

How it works

  1. Name the sugar-chain and the job (store / wall)The polysaccharide.
  2. Keep starch / glycogen / cellulose as the trioThe cases.
  3. Refuse a single sugar as this headingA chain.

6Nucleic Acids

Nucleic acids: DNA and RNA as taught — information-chains of nucleotides. A nucleic acid is a base-sequence story, not a “life juice”. One DNA-double-line mention is enough; no research dump.

A protein as DNA because both are “in the nucleus-talk” is a miss.

Figure. A nucleotide is three pieces: a phosphate, a sugar, and a base. DNA uses T; RNA uses U. The chain is phosphate-to-sugar; the bases are the letters.

How it works

  1. Name DNA or RNA and the nucleotide-chainNucleic acid.
  2. Keep information as the jobThe heading.
  3. Refuse a juice-sloganA sequence-word.

7Structure of Proteins

Structure of proteins: primary (the sequence), then fold-levels as taught (secondary helix/sheet, tertiary, quaternary if named). Structure here is a level-word, not a second “proteins are good”. A denature mention if the lesson used heat/pH.

Calling the sequence “tertiary” is a level-swap.

Figure. Each level sits on the one above. Primary is the letter order. Secondary is local hydrogen bonding. Tertiary is the whole-chain fold that makes an active site. Quaternary is only when more than one folded chain assembles.

How it works

  1. Name the level (1° sequence, then folds)The structure.
  2. Keep helix/sheet on secondary if taughtThe fold.
  3. Refuse a food-slogan as a levelA map-word.

8Enzymes

Enzymes: protein-catalysts that speed a named reaction as taught. Active site, substrate, a temperature/pH caution if listed. Enzyme is a speed-and-fit story, not a vitamin. One lock-and-key or induced-fit mention as the lesson framed it.

A hormone called an enzyme because both are “chemicals in the body” is a miss.

Figure. Enzyme plus substrate make a complex at the active site; product leaves and the enzyme is reused. The figure is the job, not a drawn pocket curve.

How it works

  1. Name protein + speed a reactionThe enzyme.
  2. Keep substrate and site if askedThe fit.
  3. Refuse a vitamin-swapA catalyst.
Enzymes at this class are
  1. Protein-catalysts that speed a named reaction
  2. Vitamins
  3. Starch grains

Speed-and-fit.

Notes

  • Mapped to the official NCERT chapter “Biomolecules”. Original teaching only — no textbook sentences.
  • Science here is Physics, Chemistry and Biology ideas at this class, never a language or social-science chapter.

Recap

Hold these pegs from the official chapter “Biomolecules”. The wording is ExamMaster’s teaching, not a textbook recap.

How to Analyse Chemical Composition?
How to analyse composition (school): dry a sample, burn or extract as taught, then name ash (inorganic) versus the carbon-rich leftover.
Primary and Secondary Metabolites
Primary metabolites are the everyday building bits (sugars, amino acids as taught); secondary are extras some species make (a named alkaloid if the lesson used one).
Biomacromolecules
Biomacromolecules: large polymers as taught — proteins, polysaccharides, nucleic acids.
Proteins
Proteins: amino-acid chains with a job (enzyme, structure as taught).
Polysaccharides
Polysaccharides: sugar-chains — starch, glycogen, cellulose as taught.
Nucleic Acids
Nucleic acids: DNA and RNA as taught — information-chains of nucleotides.

Practise Biomolecules

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