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Key Facts: GCE O/L Science Exam

Subject 34

Official Department of Examinations Subject Code

Department of Examinations, Sri Lanka

40 MCQs

Paper 1 Multiple-Choice Item Count

Department of Examinations, Sri Lanka

4 Hours

Total Examination Time (Paper 1: 1h + Paper 2: 3h)

Department of Examinations, Sri Lanka

Grade S

Minimum Passing Grade (35 Marks)

Department of Examinations, Sri Lanka

3 Languages

Administered in Sinhala, Tamil, and English

Ministry of Education, Sri Lanka

Sri Lanka GCE O/L Science (Subject Code 34) is a compulsory national examination evaluating Biology, Chemistry, and Physics across Paper 1 (40 MCQs, 1 hour) and Paper 2 (structured/essay, 3 hours). Achieving a credit pass or distinction is essential for entering the GCE A/L Science and Technology streams.

Sample GCE O/L Science Practice Questions

Try these sample questions to review concepts for the GCE O/L Science exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which cell organelle contains folded inner membrane structures called cristae and serves as the primary site of aerobic cellular respiration to generate adenosine triphosphate (ATP)?
A.Mitochondrion
B.Chloroplast
C.Endoplasmic reticulum
D.Golgi apparatus
Explanation: The mitochondrion is known as the powerhouse of the cell because it generates the majority of chemical energy in the form of ATP through aerobic cellular respiration. Its inner membrane is folded into cristae to expand the surface area for respiratory electron transport enzymes. In contrast, chloroplasts conduct photosynthesis, while endoplasmic reticulum and Golgi apparatus handle protein and lipid processing.
2Which pigment located in plant chloroplasts primarily absorbs blue and red wavelengths of sunlight while reflecting green light during the light reaction of photosynthesis?
A.Chlorophyll
B.Carotenoid
C.Anthocyanin
D.Xanthophyll
Explanation: Chlorophyll (predominantly chlorophyll a and chlorophyll b) is the primary photosynthetic pigment embedded in thylakoid membranes. It absorbs photons strongly in the blue (400–450 nm) and red (650–700 nm) spectral bands while transmitting and reflecting green light (500–550 nm), which gives leaves their characteristic green color. Accessory pigments like carotenoids absorb other wavelengths and protect chlorophyll from photo-oxidation.
3A plant palisade mesophyll cell with an actual length of 0.05 mm is observed under a light microscope. In the micrograph, the image length of the cell is measured as 20.0 mm. What is the linear magnification of this microscope image?
A.x100
B.x250
C.x1,000
D.x400
Explanation: Magnification is calculated using the formula: Magnification = Image size / Actual size. Substituting the given values: Magnification = 20.0 mm / 0.05 mm = 400. Therefore, the linear magnification of the image is x400.
4Which enzyme present in human saliva and pancreatic juice catalyzes the chemical breakdown of insoluble starch into the disaccharide maltose?
A.Amylase
B.Pepsin
C.Trypsin
D.Lipase
Explanation: Amylase (salivary amylase or ptyalin, and pancreatic amylase) specifically hydrolyzes alpha-1,4-glycosidic bonds in complex starch polysaccharides to produce the disaccharide maltose. Pepsin and trypsin digest proteins into peptides, while lipase hydrolyzes lipids into fatty acids and glycerol.
5Which chamber of the human heart contracts to pump deoxygenated blood into the pulmonary artery toward the lungs for gas exchange?
A.Right ventricle
B.Right atrium
C.Left atrium
D.Left ventricle
Explanation: The right ventricle receives deoxygenated systemic blood from the right atrium through the tricuspid valve and pumps it under moderate pressure through the pulmonary semilunar valve into the pulmonary artery toward both lungs. The left ventricle pumps oxygenated blood into the systemic aorta, while both atria act as receiving chambers.
6During a laboratory physiology experiment, a healthy student exhibits a resting heart rate of 72 beats per minute and a stroke volume of 70 mL per beat. What is the student's cardiac output in liters per minute (L min⁻¹)?
A.3.50 L min⁻¹
B.4.20 L min⁻¹
C.6.12 L min⁻¹
D.5.04 L min⁻¹
Explanation: Cardiac output is defined as the volume of blood pumped by a ventricle per minute and is calculated as: Cardiac Output = Stroke Volume * Heart Rate. Substituting the parameters: Cardiac Output = 70 mL beat⁻¹ * 72 beats min⁻¹ = 5,040 mL min⁻¹. Converting to liters (1 L = 1,000 mL): 5,040 / 1,000 = 5.04 L min⁻¹.
7During active human inhalation (inspiration), what mechanical changes occur in the diaphragm and the intercostal muscles?
A.Diaphragm contracts and flattens downward; external intercostal muscles contract to elevate the ribs
B.Diaphragm relaxes and arches upward; external intercostal muscles relax to lower the ribs
C.Diaphragm contracts and arches upward; internal intercostal muscles contract to raise the ribs
D.Diaphragm relaxes and flattens downward; internal intercostal muscles relax to expand the thorax
Explanation: During active inhalation, the diaphragm contracts and flattens downward while the external intercostal muscles contract, swinging the ribs upward and outward. These coordinated movements increase the volume of the thoracic cavity, decreasing the intrapulmonary pressure below atmospheric pressure so air rushes into the lungs.
8What is the microscopic structural and functional filtering unit of the human kidney?
A.Nephron
B.Neuron
C.Alveolus
D.Villus
Explanation: The nephron is the basic functional unit of the kidney responsible for filtering blood, selective reabsorption, secretion, and the formation of urine. Each human kidney contains approximately one million nephrons.
9In a healthy human kidney nephron, why is glucose present in the glomerular filtrate within Bowman's capsule but absent from final bladder urine?
A.Glucose molecules are too large to pass through the glomerular filtration barrier into the capsule
B.Glucose is completely oxidized into carbon dioxide and water inside the loop of Henle
C.Glucose is converted into glycogen and stored within epithelial cells of the collecting duct
D.Glucose is entirely reabsorbed back into peritubular capillaries along the proximal convoluted tubule by active transport
Explanation: Glucose is a small soluble molecule that freely passes through the glomerular filtration slits into Bowman's capsule during ultrafiltration. Under normal physiological conditions, 100% of this filtered glucose is selectively reabsorbed back into the blood along the proximal convoluted tubule via active carrier-mediated transport, leaving none in normal urine.
10A fully turgid plant cell with an internal solute potential (Ψs) of -600 kPa and pressure potential (Ψp) of +500 kPa is immersed in an open beaker containing a sucrose solution with a solute potential (Ψs) of -400 kPa. What is the initial water potential of the plant cell, and in which direction will net water osmosis occur?
A.Cell Ψ = -100 kPa; net water movement out of the cell into the solution
B.Cell Ψ = -1,100 kPa; net water movement into the cell
C.Cell Ψ = -100 kPa; net water movement from the solution into the cell
D.Cell Ψ = +100 kPa; net water movement out of the cell into the solution
Explanation: The total water potential of a plant cell is: Ψ = Ψs + Ψp. For the cell: Ψ = -600 kPa + 500 kPa = -100 kPa. For the open sucrose solution, Ψp = 0 kPa, so Ψ_sol = -400 kPa. Because water moves spontaneously down a water potential gradient from higher (less negative) to lower (more negative) potential, water moves from the cell (-100 kPa) out into the sucrose solution (-400 kPa).

About the GCE O/L Science Exam

The Sri Lanka General Certificate of Education (Ordinary Level) Science examination (Subject Code 34) is a compulsory core assessment conducted annually by the Department of Examinations, Sri Lanka, for all Grade 11 candidates. Developed in accordance with curricula formulated by the National Institute of Education (NIE), the syllabus integrates Biology, Chemistry, and Physics to cultivate systematic scientific literacy, experimental reasoning, and quantitative problem-solving skills. Achievement in Science is a decisive prerequisite for students aiming to qualify for senior secondary education in the G.C.E. Advanced Level Science streams (Physical Science and Biological Science) as well as the Technology stream. Candidates are tested on theoretical knowledge, graphical interpretation, experimental laboratory techniques, and computational exercises involving SI units, stoichiometry, circuit laws, and dynamics. This interactive question bank presents 100 comprehensive practice questions equipped with step-by-step scientific explanations to support students in mastering each key competency domain.

Exam sponsor: Department of Examinations, Sri Lanka (doenets.lk). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

The examination comprises two written papers: Paper 1 consists of 40 compulsory multiple-choice questions (1 hour, 40 marks). Paper 2 consists of Part A (four compulsory structured essay questions) and Part B (five essay questions from which three must be selected) administered over 3 hours (60 marks). Together, the two papers produce an aggregate mark out of 100.

Time Limit

Paper II: 3 hours 10 minutes (morning); Paper I: 1 hour (afternoon)

Passing Score

Grade S or higher

Exam / Certification Fees

Free for school candidates; nominal fee for private candidates

Exam sponsor website

Reported exam pass rate: Approximately 66% to 73% of candidates achieve a Grade S or higher nationally.. This describes exam candidates, not OpenExamPrep users or results from using our resources. Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

35%

Biological Processes and Systems

Cellular organization, photosynthesis, cellular respiration, human organ systems (digestive, circulatory, respiratory, excretory), plant transport, plant and animal reproduction, genetics and inheritance, and Sri Lankan ecosystems and biomes.

30%

Chemical Principles and Matter

Atomic structure and electron configuration, periodic table trends, chemical bonding, chemical formulas and balancing equations, the mole concept and stoichiometry, acids, bases and salts, reaction rates, and the metals reactivity series.

35%

Physical Phenomena and Energy

SI units and measurement, linear motion and Newton's laws of motion, force and fluid pressure, work, energy and power, thermal expansion and heat transfer, geometrical optics and refraction, wave mechanics and acoustics, direct current electricity, and electromagnetism with basic electronics.

Preparing for the GCE O/L Science Exam

What You Need to Know

  • Passing score: Grade S or higher
  • Assessment: The examination comprises two written papers: Paper 1 consists of 40 compulsory multiple-choice questions (1 hour, 40 marks). Paper 2 consists of Part A (four compulsory structured essay questions) and Part B (five essay questions from which three must be selected) administered over 3 hours (60 marks). Together, the two papers produce an aggregate mark out of 100.
  • Time limit: Paper II: 3 hours 10 minutes (morning); Paper I: 1 hour (afternoon)
  • Exam / certification fees: Free for school candidates; nominal fee for private candidates Official sources

Using Our Practice Resources

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

Frequently Asked Questions

What is the structure and mark breakdown of the GCE O/L Science examination?

The examination comprises two papers totaling 100 marks: Paper 1 contains 40 compulsory multiple-choice questions (1 hour, 40 marks). Paper 2 is a 3-hour paper totaling 60 marks, consisting of Part A (four structured essay questions, 10 marks each for 40 marks) and Part B (five long essay questions where candidates answer three, 20 marks total after scaling). Final letter grades are determined by the combined percentage score.

What grade is required in O/L Science to pursue Advanced Level Science?

To qualify for the GCE Advanced Level Science streams (Biological Science or Physical Science / Combined Mathematics), the Ministry of Education and senior secondary schools typically require at least a Credit pass (Grade C, 55 marks or higher) in both Science and Mathematics at the Ordinary Level, alongside overall qualification criteria.

In which assessment languages is GCE O/L Science available?

The examination is administered nationwide in three official media of instruction: Sinhala, Tamil, and English. Candidates sit the examination in their registered language, with identical diagrams, technical terms, and scientific formulations provided across all versions.

Are calculators allowed during the GCE O/L Science examination?

No. Electronic calculators, smart devices, and reference tables are strictly prohibited in the examination hall for both Paper 1 and Paper 2. All calculations involving moles, velocity, electrical circuits, and heat transfer must be carried out manually using paper rough work.

How are practical laboratory skills assessed in the written examination?

While there is no separate laboratory practical exam, experimental skills are thoroughly evaluated through written questions in both papers. Candidates are tested on laboratory apparatus identification, experimental setups, control variables, standard chemical tests (e.g., starch, reducing sugars, carbon dioxide), observation recording, and data analysis from graphs.