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.

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2026 Statistics

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 test your LC Biology exam readiness. 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 Practice Questions

Verified exam format metadata for Leaving Certificate Biology (Ireland) is pending. The practice questions above remain available while official exam length, timing, passing score, fee, and administrator details are reviewed.