Prepare for the Grade 11 Biology Annual Examination 2027 with our ALP Smart Syllabus Solved Biology Model Paper 2027, developed according to the new syllabus issued by PECTAA Punjab. This Punjab Board Class 11 Biology Test Series provides comprehensive exam preparation through a Chapter Wise Test Series and Full Book Test Series, featuring solved questions to help students understand important concepts and practise effectively. These Punjab Board 2027 Model Papers are designed to support students in their annual examination preparation according to the ALP Smart Syllabus 2026–27. Explore the solved Grade 11 Biology model papers and strengthen your preparation for the upcoming Punjab Board examinations.
MODEL PAPER OF BIOLOGY FOR CLASS-11
Objective Type
Paper: BIOLOGY
Q-1: You have four choices for each objective type question as A, B, C and D. The choice which you think is correct; fill that circle in front of that question number. Use marker or pen to fill the circles. Cutting or filling two or more circles will result in zero marks in that question.
1
According to Carl Woese’s system, which of the following is NOT a domain?
A) ArchaeaB) BacteriaC) ProtistaD) Eukarya
Ans: C) Protista – Woese’s three domains are Archaea, Bacteria and Eukarya; Protista is a kingdom inside Eukarya.
2
A marine biologist observes a sessile, cylindrical Cnidarian attached to a rock reproducing asexually. Which body form is it?
A) MedusaB) LarvaC) PolypD) Ephyrans
Ans: C) Polyp – the polyp is the sessile, cylindrical, asexually reproducing (budding) form; the medusa is free-swimming and sexual.
3
During sporulation, what happens to the DNA of the vegetative cell?
A) It doublesB) It disintegratesC) It remains intactD) It forms RNA
Ans: B) It disintegrates – one copy of DNA goes into the endospore; the remaining DNA of the mother (vegetative) cell breaks down when the cell lyses.
4
Which property of the lipid bilayer makes it impermeable to sugars and polar amino acids?
A) Hydrophilic interiorB) Hydrophobic interiorC) Presence of glycoproteinsD) Presence of cholesterol only
Ans: B) Hydrophobic interior – the non-polar fatty-acid tails repel polar and charged molecules.
5
If a cell has high concentration of lipids, what property of water will influence their arrangement?
A) Heat of vaporizationB) Hydrophobic exclusionC) Specific heat capacityD) Hydrogen bonding in proteins
Ans: B) Hydrophobic exclusion – water excludes non-polar lipids, which cluster together into bilayers/micelles.
6
If a DNA strand has the sequence 5’-AGCT-3’, what is its complementary strand sequence?
A) 3’-TCGA-5’B) 5’-TCGA-3’C) 3’-AGCT-5’D) 5’-AGCT-3’
Ans: A) 3’-TCGA-5’ – A pairs with T, G with C, and the strands are antiparallel (A→T, G→C, C→G, T→A, written 3’→5’).
7
The enzymes catalyse non-hydrolytic addition or removal of groups from substrate:
A) HydrolasesB) LyasesC) IsomeraseD) Transferases
Ans: B) Lyases – lyases add or remove groups (e.g. forming double bonds) without using water.
8
How does ATP synthase produce ATP during light-dependent reactions?
A) By hydrolysing glucoseB) By using light directlyC) By chemiosmosisD) By splitting NADPH
Ans: C) By chemiosmosis – H+ flow down their gradient through ATP synthase, driving ADP + Pi → ATP.
Biology Model Paper – Page 1 of 4
9
In first step of citric acid cycle Acetyl Co enzyme reacts with oxaloacetate to form
A) PyruvateB) FumarateC) IsocitrateD) Citrate
Ans: D) Citrate – acetyl-CoA (2C) + oxaloacetate (4C) → citrate (6C).
10
How does abscisic acid affect guard cells?
A) Increases K+ influxB) Promotes stomatal openingC) Inhibits K+ uptakeD) Enhances sugar formation
Ans: C) Inhibits K+ uptake – ABA stops K+ entering (and promotes its loss), guard cells lose turgor and the stomata close.
11
Cells with spherical nuclei in the centre are found in:
A) Zone of cell divisionB) Zone of elongationC) Zone of differentiationD) Epidermis
Ans: A) Zone of cell division – meristematic cells are small, dense, with a large central nucleus.
12
What is the function of the pyloric sphincter?
A) To store foodB) To allow food into the oesophagusC) To absorb nutrientsD) To regulate chyme release
Ans: D) To regulate chyme release – it controls passage of chyme from stomach to duodenum.
13
What type of ring structure holds the iron ion in a haem group?
A) Peptide ringB) Purine ringC) Porphyrin ringD) Benzene ring
Ans: C) Porphyrin ring – Fe2+ sits at the centre of a porphyrin ring in haem.
14
How long does diastole last in one complete heartbeat?
A) 0.1 secB) 0.2 secC) 0.3 secD) 0.4 sec
Ans: D) 0.4 sec – cycle = 0.8 s: atrial systole 0.1 s + ventricular systole 0.3 s + diastole 0.4 s.
15
Which ECG segment, if prolonged, might indicate a first-degree heart block?
A) PR segmentB) ST segmentC) QT intervalD) QRS complex
Ans: A) PR segment – a prolonged PR interval shows delayed conduction through the AV node.
16
Which protein is found in thick filaments?
A) ActinB) TropomyosinC) TroponinD) Myosin
Ans: D) Myosin – thick filaments are made of myosin; thin filaments contain actin, tropomyosin, troponin.
17
Which membrane covers the outer surface of bones?
A) PerichondriumB) EndosteumC) PeriosteumD) Epithelium
Ans: C) Periosteum – the fibrous membrane around bone; the endosteum lines the marrow cavity.
Biology Model Paper – Page 2 of 4
Paper: BIOLOGY (Subjective Type)
Section-I
Q. 2. Attempt any EIGHT (8) short questions.(2 × 8=16)
- Classify bacteria on the basis of respiration.
- Obligate aerobes – need O2 (e.g. Mycobacterium tuberculosis).
- Obligate anaerobes – killed by O2 (e.g. Clostridium).
- Facultative anaerobes – grow with or without O2 (e.g. E. coli).
- Microaerophiles – need low O2 (e.g. Campylobacter).
- Compare the characteristics of Protozoa and Algae with examples.
Protozoa: unicellular, heterotrophic, no cell wall, move by cilia, flagella or pseudopodia (Amoeba, Paramecium). Algae: autotrophic (chlorophyll), cellulose cell wall, unicellular or multicellular (Chlamydomonas, Spirogyra).
- Differentiate the composition of primary and secondary wall.
Primary wall: thin and flexible; cellulose, hemicellulose and pectin; formed in growing cells. Secondary wall: thick and rigid; laid inside the primary wall after growth stops; cellulose plus lignin, very little pectin.
- Write the steroid signaling for production of specific production in cells.
Lipid-soluble steroid hormone diffuses through the plasma membrane → binds its intracellular receptor → hormone-receptor complex enters the nucleus and binds specific DNA (response element) → gene is transcribed → mRNA → translated into the specific protein.
- Define nuclear pore complex? Write the name of its sub units.
A large protein structure forming a channel in the nuclear envelope that controls movement of molecules between nucleus and cytoplasm. Sub-units (nucleoporins): cytoplasmic ring, nuclear ring, spokes (central transporter) and nuclear basket.
- How are vessels different from tracheids in structure?
Vessels: short, wide, end walls perforated, joined end-to-end into continuous tubes. Tracheids: long, narrow, tapered with intact end walls; water moves through pits.
- How would sugar transport be affected if sucrose were not actively loaded into the phloem?
Active loading lowers water potential in the sieve tubes, so water enters by osmosis and builds turgor pressure. Without it, no pressure gradient forms, bulk flow slows or stops and sinks (roots, fruits) do not receive sugar.
- How plants protect themselves in freezing temperature and high temperature.
Freezing: increase solutes/antifreeze proteins, more unsaturated fatty acids in membranes, dormancy. High temperature: heat-shock proteins, cooling by transpiration, thick cuticle, reflective hairs, leaf orientation.
- Differentiate Autumn wood and spring wood.
Spring wood: formed in spring; wide vessels, thin walls, light colour. Autumn wood: formed in autumn; narrow vessels, thick walls, dark and dense. Together they make an annual ring.
- Write the structure of layers which separate heart from other parts.
The pericardium: outer tough fibrous pericardium and inner serous pericardium (parietal and visceral layers) with pericardial fluid between them to reduce friction.
- What is a SA node? Give its functions.
The sino-atrial node is a patch of specialized cardiac muscle in the right atrium wall near the superior vena cava. It is the pacemaker: it generates impulses (about 70 per minute) that spread over the atria, causing them to contract.
- Give the importance of Hepatic portal vein.
It carries nutrient-rich blood from the intestine to the liver, where glucose is regulated and stored, amino acids processed and toxins removed before blood reaches the general circulation.
Q. 3. Attempt any EIGHT (8) short questions.(2 × 8=16)
- How does the structure of bacterial flagellum differ from eukaryotic flagellum?
Bacterial: thin flagellin filament, hook and basal body, no membrane cover, rotates like a propeller (proton motive force). Eukaryotic: 9+2 microtubules covered by plasma membrane, bends in a whip-like wave using ATP.
- What are mesosomes? What are its functions?
Infoldings of the bacterial plasma membrane. Functions: cell-wall formation during division, attachment and separation of replicated DNA, site of respiratory enzymes, secretion.
- What are the coenzymes? Give two examples.
Non-protein organic helper molecules (often from vitamins) that loosely bind enzymes and carry groups or electrons. Examples: NAD+ and FAD (also coenzyme A).
- Differentiate between reversible and irreversible inhibitors?
Reversible: bind by weak bonds and can be removed (competitive, non-competitive). Irreversible: bind by strong covalent bonds and permanently inactivate the enzyme (cyanide, nerve gases, heavy metals).
- What is hydrolase/? Give three examples
Enzymes that catalyse hydrolysis, i.e. breaking bonds by adding water. Examples: lipase, amylase, pepsin (also maltase, trypsin).
- Write the function of chief cells and oxyntic cells.
Chief cells secrete pepsinogen (precursor of pepsin). Oxyntic (parietal) cells secrete HCl and intrinsic factor.
- Why doesn’t food go into the windpipe when we swallow?
During swallowing the larynx rises and the epiglottis folds over the glottis, closing the windpipe so food goes into the oesophagus.
- Differentiate between chyme and chyle.
Chyme: acidic, semi-liquid partly digested food in the stomach. Chyle: milky lymph in the lacteals of villi, rich in absorbed emulsified fat.
- Differentiate epiphyses and diaphysis.
Epiphyses: expanded ends of a long bone, spongy bone with red marrow, capped by articular cartilage. Diaphysis: the shaft, compact bone around a hollow cavity with yellow marrow.
- Define muscle and muscle fibres.
Muscle: tissue specialized to contract and produce movement. Muscle fibre: a long, cylindrical, multinucleate cell packed with myofibrils (actin and myosin).
- Evaluate the role of acetylcholine in muscle contraction.
Released by the motor neuron at the neuromuscular junction, it binds sarcolemma receptors and triggers an action potential. This releases Ca2+ from the sarcoplasmic reticulum, which starts contraction.
- Define tetany. How it is treated?
Tetany is sustained, painful involuntary muscle spasm caused by low blood calcium (hypocalcaemia, e.g. low parathyroid hormone). Treatment: calcium (and vitamin D) supplements, treating the cause.
Q. 4. Attempt any SIX (6) short questions.(2 × 6=12)
- Draw the structural formula of α-D- glucose and β-D-glucose
Haworth (ring) structures – they differ only in the position of –OH on carbon 1:Molecular formula of both: C6H12O6 (hydrogens on C2–C5 omitted for clarity).
α-D-glucose (–OH on C1 below the ring) β-D-glucose (–OH on C1 above the ring) - Differentiate the composition of milk sugar and cane sugar.
Milk sugar (lactose) = glucose + galactose joined by a β-1,4 glycosidic bond. Cane sugar (sucrose) = glucose + fructose joined by an α-1,2 glycosidic bond.
- What are prostaglandins? Write any three functions.
Local hormone-like lipids made from 20-carbon fatty acids (arachidonic acid). Functions: (1) cause inflammation, pain and fever; (2) stimulate uterine contractions in childbirth; (3) protect stomach lining / regulate blood flow and platelet clotting.
- Write the equations showing alcoholic and lactic acid fermentation.
Alcoholic:C6H12O6 → 2 Pyruvate → 2 CH3CHO + 2 CO2 → 2 C2H5OHNet: C6H12O6 → 2 C2H5OH + 2 CO2 + 2 ATPLactic acid:C6H12O6 → 2 Pyruvate → 2 CH3CH(OH)COOH + 2 ATP
- Differentiate between photosynthesis and respiration
Photosynthesis: in chloroplasts, needs light, anabolic, stores energy, 6CO2 + 6H2O → C6H12O6 + 6O2. Respiration: in cytoplasm and mitochondria, goes on day and night, catabolic, releases energy as ATP, C6H12O6 + 6O2 → 6CO2 + 6H2O.
Biology Model Paper – Page 3 of 4
- Define compensation point. When does it occur?
The light intensity at which the rate of photosynthesis equals the rate of respiration, so there is no net gas exchange. It occurs at dawn and dusk (low light).
- Define pleural cavity. How is it formed?
A thin fluid-filled space between the two layers of the pleura around each lung. The visceral pleura covers the lung and the parietal pleura lines the chest wall; the gap between them holds pleural fluid that reduces friction.
- Give the role of diaphragm in breathing.
Inhalation: diaphragm contracts and flattens, thoracic volume rises, pressure falls, air enters. Exhalation: it relaxes into a dome, volume falls, air leaves.
- What is myoglobin? Give its one function.
An oxygen-binding protein of muscle (one polypeptide with one haem). Function: stores O2 in muscle and releases it when demand is high.
(Section-II)
Note: Attempt any THREE questions.(8 × 3 = 24)
Q. 5.a)What are the main features of chordates?(4)
- Notochord (flexible rod) at some stage.
- Dorsal, hollow nerve cord.
- Pharyngeal gill slits.
- Post-anal tail; ventral heart with closed circulation.
- Bilateral symmetry, coelom and segmentation.
b)Justify in what way blood circulatory system of humans is dependent on lymphatic system.(4)
Fluid constantly leaks from capillaries as tissue fluid. The lymphatic system collects it and returns it to the blood through the subclavian veins, keeping blood volume and pressure normal and preventing oedema. It also returns leaked proteins, carries absorbed fats from lacteals and its nodes defend against infection.
Q. 6.a)Describe the structure of a mitochondrion in detail. How does its structure relate to its function in the cell?(4)
- Outer membrane: smooth, permeable.
- Inner membrane: folded into cristae that increase surface area and carry the electron transport chain and ATP synthase.
- Intermembrane space: H+ accumulate here for chemiosmosis.
- Matrix: Krebs-cycle enzymes, circular DNA, 70S ribosomes.
b)Small intestine walls are well adapted for absorption of food. Justify.(4)
- Very long (about 6 m).
- Folds, villi and microvilli greatly increase surface area.
- One-cell-thick epithelium for short diffusion distance.
- Rich capillary network and a lacteal in each villus carry absorbed food away.
- Muscular wall mixes food; goblet cells and glands add mucus and enzymes.
Q. 7.a)How does chemiosmosis couple redox reactions with ATP formation?(4)
Redox reactions of the electron transport chain pass electrons from NADH/FADH2 through carriers; the released energy pumps H+ across the inner mitochondrial (or thylakoid) membrane, forming a proton gradient. H+ then flow back through ATP synthase, whose rotation drives ADP + Pi → ATP. The gradient thus links electron flow to ATP synthesis.
b)Explain the structure of lungs.(4)
Lungs are a pair of spongy, cone-shaped organs in the thoracic cavity, covered by pleura. The right lung has three lobes and the left has two (with a cardiac notch). The trachea divides into bronchi → bronchioles → clusters of alveoli. Alveoli have thin walls, a dense capillary network and surfactant for gas exchange.
Q. 8.a)Describe the process of sporulation in bacteria.(4)
In harsh conditions (e.g. Bacillus, Clostridium): (1) DNA replicates; (2) a septum cuts off one DNA copy with some cytoplasm as the forespore; (3) the mother cell engulfs it and a thick cortex and spore coat form; (4) the mother cell disintegrates releasing the endospore. It germinates into a vegetative cell when conditions improve.
b)Describe the steps involved in the sliding filament model of muscle contraction.(4)
- Nerve impulse releases ACh; Ca2+ is freed from the sarcoplasmic reticulum.
- Ca2+ binds troponin; tropomyosin moves, exposing binding sites on actin.
- Myosin heads (charged with ATP-derived energy) bind actin, forming cross-bridges.
- Heads pivot (power stroke) and pull actin towards the sarcomere centre; the sarcomere shortens.
- New ATP detaches the heads and the cycle repeats; at relaxation Ca2+ returns to the SR.
Q. 9.a)Justify the significance of the sequence of amino acids through the example of sickle cell anemia.(4)
In the β-chain of haemoglobin, glutamic acid (polar) at position 6 is replaced by valine (non-polar) through one base change (GAG → GUG). Haemoglobin S then sticks together at low O2, red cells become sickle-shaped, block capillaries and break down, causing anaemia and pain. A single wrong amino acid can change protein shape and function.
b)Explain in detail the pressure-flow hypothesis for phloem translocation.(4)
At the source (leaf) sucrose is actively loaded into sieve tubes, lowering water potential; water enters from the xylem by osmosis and turgor pressure rises. At the sink sucrose is unloaded and used or stored, water leaves and pressure falls. This pressure gradient pushes sap by bulk flow through the sieve tubes from source to sink.
Biology Model Paper – Page 4 of 4
