Cellulose is mainly found in:
- Animal cells
- Fungal cell walls
- Plant cell walls
- Bacterial capsules
Show answer and explanation
Answer: C. Plant cell walls
Cellulose, a polymer of β-glucose, is the main structural component of plant cell walls.
FSC Biology: Biological Molecules, questions with answers
Practise 17 real Federal Board questions on Biological Molecules from 2023 to 2026. See the answer and explanation as soon as you answer.
17real questions
9multiple choice
5exam sessions
About Biological Molecules in FSC Biology
Biological Molecules is one of the 15 main chapters in our Federal Board FSC Biology question bank (11th class), and about 3% of its real questions come from it. Tayyari Karo has 17 real questions on this chapter from 2023 to 2026; 9 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 13 medium, 4 easy.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
Try 8 real questions
These are real past-paper questions. Think of your answer first, then open the explanation.
A triglyceride molecule is formed by:
- One fatty acid and one glycerol
- Two fatty acids and one phosphate
- Three fatty acids and one glycerol
- Amino acids and glycerol
Show answer and explanation
Answer: C. Three fatty acids and one glycerol
A triglyceride (fat) forms when one glycerol molecule esterifies with three fatty acid molecules, releasing three water molecules.
Which of the following is NOT a carbohydrate?
- Glucose
- Starch
- Hemoglobin
- Cellulose
Show answer and explanation
Answer: C. Hemoglobin
Haemoglobin is a protein; glucose, starch and cellulose are all carbohydrates.
Which polysaccharide serves as the main structural component of plant cell walls?
- Starch
- Cellulose
- Glycogen
- Chitin
Show answer and explanation
Answer: B. Cellulose
Cellulose, a polymer of β-glucose, forms the rigid structural fibres of plant cell walls; starch/glycogen are storage polysaccharides and chitin is found in fungal walls/arthropod exoskeletons.
High specific heat capacity of water helps in:
- Thermo stabilization
- Producing cooling effect
- Maintaining pH of medium
- Transport of materials
Show answer and explanation
Answer: A. Thermo stabilization
Because water absorbs/releases a large amount of heat with little temperature change, it keeps the internal temperature of organisms and water bodies stable (thermo stabilization).
Natural rubber is a type of:
- Waxes
- Phospholipids
- Terpenes
- Steroids
Show answer and explanation
Answer: C. Terpenes
Natural rubber (polyisoprene) is a polymer of isoprene units and belongs to the terpene class of lipids.
Describe three effects of amino acid sequence change in haemoglobin.
Show model answer
(1) A single amino-acid substitution (e.g. glutamic acid → valine at position 6 of the β-chain) can change haemoglobin's three-dimensional shape, as in sickle-cell haemoglobin (HbS). (2) This altered shape can cause haemoglobin molecules to polymerise into rigid rods under low oxygen, distorting the red blood cell into a sickle shape. (3) The abnormal haemoglobin may have reduced oxygen-carrying capacity and the sickle-shaped cells can block small blood vessels, causing pain crises and chronic anaemia.
Distinguish between saturated and unsaturated fatty acids with examples.
Show model answer
Saturated fatty acids contain no carbon–carbon double bonds; the hydrocarbon chain is fully 'saturated' with hydrogen atoms, giving a straight chain that packs tightly and is typically solid at room temperature (e.g. palmitic acid, found in animal fats/butter).
Unsaturated fatty acids contain one or more carbon–carbon double bonds, which introduce kinks in the chain, preventing tight packing, so they are typically liquid at room temperature (e.g. oleic acid, found in olive oil).
Sessions with Biological Molecules questions
| Session | Questions |
|---|---|
| 2026 Annual | 3 |
| 2025 1st Annual | 3 |
| 2025 2nd Annual | 4 |
| 2024 Annual | 5 |
| 2023 Annual | 2 |
Common questions
What does the Biological Molecules chapter cover on this page?
17 real Federal Board (FBISE) Biology questions on Biological Molecules from 2023 to 2026, for 11th class. Each one shows the session it came from.
Are the answers official?
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.
Is it free?
You can start free with no signup. A small set of papers per subject is free, and Premium unlocks the full question bank.