Practise 19 real Federal Board questions on Macromolecules/Biochemistry from 2023 to 2026. See the answer and explanation as soon as you answer.
Macromolecules/Biochemistry is one of the 19 main chapters in our Federal Board FSC Chemistry question bank (12th class), and about 4% of its real questions come from it. Tayyari Karo has 19 real questions on this chapter from 2023 to 2026; 6 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 12 medium, 4 easy, 3 hard.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
Enzyme activity is affected by:
Answer: D. Temperature
Enzyme activity is strongly affected by temperature (as well as pH and substrate concentration), since these affect the enzyme's 3-D shape and collision frequency.
Succinic acid resembles substrate and inhibits the enzyme activity by attaching on its active site. It is an example of:
Answer: C. Competitive inhibition
An inhibitor that mimics the substrate and binds at the active site itself is a classic example of competitive inhibition.
A fire fighter's helmet made of plastic becomes hard after a fire. Helmet is made of:
Answer: D. Thermo setting plastic
Thermosetting plastics undergo permanent cross-linking on strong heating and harden irreversibly, unlike thermoplastics which soften.
The building blocks of proteins are:
Answer: C. Amino acids
Proteins are polymers of amino acids linked by peptide bonds.
Which of the following is NOT a disaccharide:
Answer: A. Galactose
Galactose is a monosaccharide; sucrose, maltose and lactose are all disaccharides.
Which statement about glucose and sucrose is incorrect:
Answer: D. Both are disaccharides
Glucose is a monosaccharide, not a disaccharide; only sucrose is a disaccharide, so this statement is false.
Draw the zwitterionic form of an amino acid and label the acidic and basic sites.
A generic amino acid H₂N-CHR-COOH exists as a zwitterion: ⁺H₃N-CHR-COO⁻
The -COO⁻ (carboxylate) group is the acidic site (formed by donation of a proton — conjugate base of -COOH).
The -NH₃⁺ (protonated amine) group is the basic site (formed by accepting that proton — conjugate acid of -NH₂).
The molecule carries both a positive and negative charge simultaneously (net neutral), characteristic of the zwitterion.
Draw the open chain and closed chain structures for Glucose and Fructose.
Glucose: open-chain form is CH₂OH-(CHOH)₄-CHO (an aldohexose); its closed (cyclic) form is a six-membered pyranose ring (hemiacetal formed between C1 aldehyde and C5-OH).
Fructose: open-chain form is CH₂OH-(CHOH)₃-CO-CH₂OH (a ketohexose); its closed (cyclic) form is a five-membered furanose ring (hemiketal formed between C2 ketone and C5-OH).
| Session | Questions |
|---|---|
| 2026 Annual | 4 |
| 2025 1st Annual | 5 |
| 2025 2nd Annual | 4 |
| 2024 Annual | 4 |
| 2023 Annual | 2 |
19 real Federal Board (FBISE) Chemistry questions on Macromolecules/Biochemistry from 2023 to 2026, for 12th class. Each one shows the session it came from.
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
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