Overview
Science subjects are among the most popular Leaving Cert choices. There are three main science subjects: Biology, Chemistry and Physics. Agricultural Science is also available but covered separately. Each subject is examined at Higher and Ordinary Level, with a mix of written exams and practical coursework components.
Leaving Cert Biology
Biology is consistently the most popular Leaving Cert subject, taken by over 30,000 students annually.
Course Content
- Unit 1: The Study of Life: scientific method, characteristics of life, ecology
- Unit 2: The Cell: cell structure, cell division (mitosis, meiosis), DNA, RNA, protein synthesis, genetics, enzymes
- Unit 3: The Organism: photosynthesis, respiration, human systems (digestive, circulatory, nervous, immune, excretory), plant biology
Exam Structure
- Two written papers (or one long paper depending on year): 3 hours each at HL
- Mandatory practical activities: 22 specified experiments (10 — 12 assessed in the exam)
- Questions test recall of facts, application of biological concepts and experimental design
Tips for Biology
- Learn the definitions precisely: examiners expect exact terminology
- Draw and label diagrams: practice cell diagrams, heart, kidney, leaf cross-section, DNA structure
- Know the mandatory experiments inside out: aim, method, result, conclusion
- Biology is content-heavy: start revision early and use flashcards
Leaving Cert Chemistry
Chemistry is required or recommended for medicine, pharmacy, veterinary science, dentistry and many science courses.
Course Content
- Unit 1: Atomic structure, periodic table, bonding, mole concept, stoichiometry
- Unit 2: Rates of reaction, equilibrium, acids and bases, oxidation-reduction, electrochemistry
- Unit 3: Organic chemistry: hydrocarbons, alcohols, carboxylic acids, organic reactions, polymers
- Unit 4: Option topics: atmospheric chemistry, materials, industrial chemistry (varies by year)
Exam Structure
- Two papers: Paper 1 (short questions + longer Qs on Units 1 & 2), Paper 2 (Units 3 & 4)
- 28 mandatory experiments: questions appear regularly on the exam
- Calculations are a significant part: balancing equations, mole calculations, pH, E° values
Tips for Chemistry
- Practice calculations daily: the mole concept is central to the entire course
- Learn the trends in the periodic table (ionisation energy, electronegativity, atomic radius)
- Memorise organic reactions: functional groups, reaction types and reagents
- Know the colour changes and equations for every mandatory experiment
Leaving Cert Physics
Physics is essential for most engineering courses and is highly valued for computer science and architecture.
Course Content
- Unit 1: Optics: reflection, refraction, lenses, wave nature of light
- Unit 2: Mechanics: vectors, forces, Newton's laws, energy, momentum, circular motion, gravity
- Unit 3: Electricity & Magnetism: circuits, resistance, capacitance, electromagnetism, induction
- Unit 4: Modern Physics: quantum theory, radioactivity, nuclear physics, particle physics
- Unit 5: Heat & Thermodynamics
Exam Structure
- Two papers: Paper 1 (Mechanics, Heat, Optics), Paper 2 (Electricity, Modern Physics, Options)
- Mandatory experiments: 22 practical activities, tested in the written exam
- Mathematical problem solving is central: students must be comfortable with algebra
Tips for Physics
- Learn the equations and understand when to apply each one: formula sheet is provided but knowing which to use is key
- Practice derivations: many exam questions ask you to derive a formula (e.g., F=ma from Newton's laws)
- Draw diagrams for every problem: labelled free-body diagrams are essential
- Do past exam questions by topic: Physics questions follow very predictable patterns
Which Science Subject Should You Choose?
- Biology: Good if you have strong memory skills. Great for medicine, nursing, physiotherapy, genetics, environmental science
- Chemistry: Good if you can handle calculations and like logical systems. Essential for medicine, pharmacy, dentistry, chemical engineering
- Physics: Good if you are strong at maths and problem solving. Essential for engineering, architecture, physics, computer science
- Two sciences: Many ambitious students take Biology + Chemistry or Chemistry + Physics to maximise course options