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Biomolecules

Life Science / Biology

Useful for: OSSC RHT — Regular High School Teacher, OSEPA Upper Primary — Science, OSSC Science, OSSSC Govt TGT Science — CBZ, SSB Lecturer (Degree Colleges), SSB TGT CBZ

Overview

Biomolecules — carbohydrates, proteins, lipids and nucleic acids — build cells and carry out life processes; enzymes speed up reactions.

Key points

Carbohydrates: monosaccharides (glucose), disaccharides (sucrose), polysaccharides (starch, cellulose, glycogen).
Proteins are made of amino acids (20 common types) linked by peptide bonds.
Lipids include fats, oils and phospholipids in membranes.
Nucleic acids (DNA, RNA) are made of nucleotides.
Most enzymes are proteins and act as biological catalysts.
Enzyme action is specific (lock-and-key model) and affected by temperature and pH.

Explanation

Cellulose is the most abundant organic compound and is not digested by humans.
Glycogen is the storage carbohydrate in animals.
Denaturation destroys protein shape and function.
Vitamins act as coenzymes in many reactions.
Iodine test detects starch; Benedict’s test detects reducing sugars.

Step by step

Identify the concept, law or fact asked.
Recall the definition, formula, example or year.
Apply it and eliminate mismatched options.

Examples

Starch turns blue-black with iodine → starch test.
Pepsin works in acidic stomach → pH optimum.
Boiling an enzyme stops its action → denaturation.

Traps and advanced points

Trap: Saying all enzymes are lipids.
Trap: Mixing glycogen and starch.
Trap: Ignoring pH effects.

Quick revision

Four biomolecule classes.
20 amino acids.
Enzymes: specific, pH and temperature sensitive.

Practice MCQs

The storage carbohydrate in animals is —
1. glycogen
2. sucrose
3. starch
4. cellulose
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Answer: (a) glycogen. Glycogen.
Proteins are made of —
1. glucose
2. nucleotides
3. amino acids
4. fatty acids
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Answer: (c) amino acids. Amino acids linked by peptide bonds.
How many common amino acids form proteins?
1. 10
2. 20
3. 30
4. 64
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Answer: (b) 20. 20.
DNA and RNA are made of —
1. nucleotides
2. monosaccharides
3. lipids
4. amino acids
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Answer: (a) nucleotides. Nucleotides.
Most enzymes are —
1. lipids
2. proteins
3. carbohydrates
4. minerals
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Answer: (b) proteins. Biological catalysts.
Enzyme specificity is explained by the —
1. double helix only
2. lock-and-key model
3. Bohr model
4. fluid model
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Answer: (b) lock-and-key model. Lock-and-key.
Starch gives a blue-black colour with —
1. Benedict’s solution
2. biuret
3. litmus
4. iodine
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Answer: (d) iodine. Iodine test.
Boiling an enzyme usually —
1. increases its activity
2. denatures it
3. has no effect
4. makes it a lipid
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Answer: (b) denatures it. Heat destroys its shape.

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Notes and questions are written by Kundali IQ for practice. They are not official papers; always check the latest official notification for the syllabus and pattern.