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Free Practice Questions for LC Biology

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Key Facts: LC Biology Exam

3 units

The syllabus is organised into The Study of Life, The Cell and The Organism

Curriculum Online - Leaving Certificate Biology

400 marks

The current written Biology paper is worth 400 marks over 3 hours

State Examinations Commission - Biology papers

3 sections

Section A short questions, Section B experiment questions and Section C long questions

State Examinations Commission - Biology papers

Higher and Ordinary

Biology is examined at two levels, Higher and Ordinary

Curriculum Online - Leaving Certificate Biology

June 2026

The current Biology syllabus is examined for the last time in June 2026

NCCA - Leaving Certificate Biology

40% minimum

The revised specification adds a non-written assessment component worth at least 40%, first examined 2027

gov.ie - Leaving Certificate subject reform

H1-H8 / O1-O8

Grades are awarded on the senior-cycle 90-point grading scale

State Examinations Commission - Grading

100

Free original multiple-choice practice questions in this bank

OpenExamPrep

Leaving Certificate Biology is an Irish senior-cycle science subject examined by the State Examinations Commission (SEC) at Higher and Ordinary Level. The written paper is a single 3-hour, 400-mark exam with three sections: Section A short questions (100 marks, 5 of 7), Section B experiment questions (60 marks, 2 of 3) and Section C long questions (240 marks, 4 of 7). The syllabus covers three units: The Study of Life, The Cell, and The Organism, spanning cell biology, metabolism, genetics, evolution, ecology, plant biology and human physiology. The current syllabus is examined last in June 2026, with a revised specification (40%+ additional assessment component) first examined in 2027. This 100-question multiple-choice bank drills the core content common to both specifications.

Sample LC Biology Practice Questions

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

1Which feature is found in plant cells but NOT in animal cells?
A.Cell membrane
B.Nucleus
C.Cell wall
D.Cytoplasm
Explanation: A rigid cell wall made of cellulose surrounds the plant cell membrane and gives the cell shape and support. Animal cells have a flexible cell membrane but no cell wall.
2Which organelle is the main site of aerobic respiration in a eukaryotic cell?
A.Ribosome
B.Mitochondrion
C.Chloroplast
D.Golgi apparatus
Explanation: The mitochondrion is the site of aerobic respiration, where glucose is fully broken down using oxygen to release ATP energy. Its folded inner membrane (cristae) increases the surface area for these reactions.
3Enzymes are biological catalysts. What does a catalyst do to a chemical reaction?
A.Increases the activation energy needed
B.Speeds up the reaction without being used up
C.Is permanently changed by the reaction
D.Provides energy for the reaction
Explanation: A catalyst speeds up the rate of a reaction by lowering the activation energy and is not used up, so it can be reused. Enzymes are protein catalysts that work in this way in living cells.
4According to the 'lock and key' model, why does an enzyme usually act on only one type of substrate?
A.The enzyme is destroyed by other substrates
B.The active site has a specific shape complementary to the substrate
C.Enzymes only work at one fixed temperature
D.Substrates are too large to fit any enzyme
Explanation: Enzyme specificity arises because the active site has a particular shape that fits only a substrate with a complementary shape, like a key fitting one lock. Other molecules cannot bind productively.
5An enzyme works fastest at 40 degrees Celsius. At 70 degrees Celsius its activity falls almost to zero. The best explanation is that at 70 degrees Celsius the enzyme has been:
A.Used up as a reactant
B.Denatured, changing the active site shape
C.Converted into its substrate
D.Diluted by extra water
Explanation: High temperatures break the bonds holding an enzyme's three-dimensional shape, so the active site changes shape and can no longer bind substrate. This permanent loss of function is called denaturation.
6In which part of the chloroplast does the light stage of photosynthesis take place?
A.Stroma
B.Thylakoid membranes (grana)
C.Outer membrane
D.Intermembrane space
Explanation: The light stage occurs on the thylakoid membranes that are stacked into grana, where chlorophyll absorbs light and water is split. The light-independent (dark) stage occurs in the surrounding stroma.
7Which word equation correctly summarises photosynthesis?
A.glucose + oxygen -> carbon dioxide + water
B.carbon dioxide + water -> glucose + oxygen
C.glucose + water -> carbon dioxide + oxygen
D.oxygen + water -> glucose + carbon dioxide
Explanation: In photosynthesis, carbon dioxide and water are combined using light energy to make glucose, releasing oxygen as a by-product. The reverse equation describes respiration.
8During the light stage of photosynthesis, water molecules are split. This process is called:
A.Photolysis
B.Glycolysis
C.Hydrolysis
D.Carboxylation
Explanation: Photolysis is the light-driven splitting of water, producing hydrogen ions, electrons and oxygen gas. The oxygen released by plants comes from this splitting of water.
9Which molecule is the universal energy carrier produced during respiration and used to power cell activities?
A.ADP
B.ATP
C.DNA
D.NaCl
Explanation: ATP (adenosine triphosphate) stores and transfers energy in cells; energy is released when ATP is broken down to ADP and phosphate. Respiration regenerates ATP from ADP.
10Anaerobic respiration in human muscle cells produces a small amount of ATP and which waste product?
A.Ethanol
B.Lactic acid
C.Carbon dioxide only
D.Oxygen
Explanation: When oxygen is in short supply, human muscle cells respire anaerobically, converting glucose to lactic acid and releasing a small amount of ATP. Build-up of lactic acid contributes to muscle fatigue.

About the LC Biology Exam

Leaving Certificate Biology is a senior-cycle science subject in Ireland, examined by the State Examinations Commission (SEC) and assessed at Higher and Ordinary Level. The current syllabus is organised into three units: Unit 1 The Study of Life (biology basics, the cell, cell metabolism and ecology), Unit 2 The Cell (cell structure, cell continuity, DNA and protein synthesis, genetics and evolution) and Unit 3 The Organism (diversity of organisms, plant structure and processes, and human physiology). The written examination is a single three-hour, 400-mark paper with short questions, experiment-based questions and long questions, and the course includes mandatory student practical activities. The current syllabus is examined for the last time in June 2026; a revised specification, in which a non-written additional assessment component is worth a minimum of 40% of the marks, is first examined in 2027.

Exam sponsor: State Examinations Commission (SEC), Ireland. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Single 3-hour written paper worth 400 marks at Higher or Ordinary Level: Section A (100 marks, answer 5 of 7 short questions), Section B (60 marks, answer 2 of 3 experiment-based questions) and Section C (240 marks, answer 4 of 7 long questions).

Time Limit

3 hours for the written examination at both Higher and Ordinary Level.

Passing Score

No pass/fail mark for the subject. Biology is graded H1-H8 (Higher) and O1-O8 (Ordinary); grades at or above H6/O6 award CAO points, and many third-level courses require specific minimum grades for entry.

Exam / Certification Fees

There is no separate fee for Biology alone; a single Leaving Certificate entry fee covers all subjects, with an exemption for medical-card holders. Confirm the current amount with your school and the State Examinations Commission.

Exam sponsor website

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.

30%

Unit 1: The Study of Life

Biology basics and characteristics of life, cell structure and metabolism (enzymes, photosynthesis and respiration), and ecology including ecosystems, food chains and webs, energy flow, nutrient cycles (carbon and nitrogen), populations and the study of an ecosystem. Practice here covers enzyme action, the light and dark stages of photosynthesis, aerobic and anaerobic respiration, and ecological relationships.

30%

Unit 2: The Cell

Detailed cell structure and ultrastructure, cell continuity through mitosis and meiosis, DNA and RNA structure, DNA replication and protein synthesis (transcription and translation), Mendelian genetics and heredity, genetic engineering, and the theory of evolution and variation. Practice here covers chromosomes, the genetic code, monohybrid and dihybrid crosses, mutations, and natural selection.

40%

Unit 3: The Organism

Diversity of organisms (kingdoms, bacteria, fungi, viruses), structure and life processes in flowering plants (transport, nutrition, growth regulators and reproduction), and human physiology including digestion, blood and circulation, the heart, breathing, excretion, the skin and homeostasis, the nervous and endocrine systems, the senses, the musculoskeletal and immune systems, and human reproduction. Practice here covers organ systems, transport mechanisms and regulation.

Preparing for the LC Biology Exam

What You Need to Know

  • Passing score: No pass/fail mark for the subject. Biology is graded H1-H8 (Higher) and O1-O8 (Ordinary); grades at or above H6/O6 award CAO points, and many third-level courses require specific minimum grades for entry.
  • Assessment: Single 3-hour written paper worth 400 marks at Higher or Ordinary Level: Section A (100 marks, answer 5 of 7 short questions), Section B (60 marks, answer 2 of 3 experiment-based questions) and Section C (240 marks, answer 4 of 7 long questions).
  • Time limit: 3 hours for the written examination at both Higher and Ordinary Level.
  • Exam / certification fees: There is no separate fee for Biology alone; a single Leaving Certificate entry fee covers all subjects, with an exemption for medical-card holders. Confirm the current amount with your school and the State Examinations Commission. 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

LC Biology: Suggested Study Strategy

1Learn the precise definitions the syllabus expects (for example enzyme, homeostasis, mitosis, gene) because Section A short questions reward accurate biological terminology.
2Master the mandatory experiments early: Section B is worth 60 marks and asks directly about apparatus, method, results and sources of error.
3For photosynthesis and respiration, learn the word equations, the location in the cell, and the difference between the light/dark and aerobic/anaerobic stages.
4Practise genetics crosses (monohybrid and dihybrid) by drawing Punnett squares and stating phenotype and genotype ratios clearly.
5Use a clear labelled diagram for structures such as the heart, nephron, neuron and flower; examiners award marks for correctly labelled parts.
6Work through past SEC papers and marking schemes from the examinations.ie archive to see how long-answer marks are split, then use concept questions like these to check recall.

Frequently Asked Questions

How is the Leaving Certificate Biology exam structured?

The current written exam is a single 3-hour, 400-mark paper at Higher or Ordinary Level. It has Section A (short questions, 100 marks, answer 5 of 7), Section B (experiment-based questions, 60 marks, answer 2 of 3) and Section C (long questions, 240 marks, answer 4 of 7).

What topics are covered in Leaving Cert Biology?

The syllabus has three units: Unit 1 The Study of Life (the cell, enzymes, photosynthesis, respiration and ecology), Unit 2 The Cell (cell structure, cell division, DNA, genetics, genetic engineering and evolution) and Unit 3 The Organism (diversity of organisms, plant biology and human physiology).

Is Leaving Cert Biology multiple choice?

No. The official SEC examination uses short and long written-answer questions, plus experiment-based questions, not multiple choice. This free bank uses single-best-answer multiple-choice questions on the same core content to help you check recall and understanding while you revise.

Is the Leaving Cert Biology syllabus changing?

Yes. The current syllabus is examined for the last time in June 2026. A revised specification, in which a non-written additional assessment component is worth at least 40% of the marks, is first examined in 2027. This bank focuses on core biology content common to both.

How is Leaving Cert Biology graded?

There is no pass/fail mark. Biology is graded H1-H8 at Higher Level and O1-O8 at Ordinary Level on the 90-point scale. Grades at H6/O6 or above earn CAO points, and individual courses may require specific minimum grades for entry.

Are these official SEC questions?

No. These are original OpenExamPrep questions written to match the Leaving Certificate Biology core content. Official past papers and marking schemes are available free from the State Examinations Commission examination material archive.