A Level Biology Topics: Complete Overview

Staring at an A Level Biology specification for the first time is overwhelming. Eight or more topic areas, dozens of subtopics, and no clear sense of which bits actually show up in your exam papers.

Revision time is limited. Spend it on the wrong content, or miss a chunk of the spec entirely, and you're walking into the exam hall with gaps you didn't know you had.

This guide breaks down the A Level Biology topics for every major specification, so you know exactly what you need to cover and how it's assessed. Read on to find out more.

Key Takeaways

• A Level Biology topics vary by exam board, so check the list that matches your specification.

• This article covers AQA (7402), OCR (H420), Edexcel SNAB (9BN0), and CIE (9700).

• Each topic list is broken down by paper, so you can see exactly what's examined where.

• Use the tables below to build a revision checklist and track what you've covered.

Why It's Important to Know Your Exam Board

Exam boards don't teach the same version of A Level Biology.

They set their own specifications, and the topics, structure, and even terminology can differ between them.

Some specifications group content thematically, like AQA's eight numbered topics. Others, like Edexcel SNAB, teach Biology through real-world contexts such as cardiovascular disease or forensic science.

That difference matters for revision. A topic list built for AQA won't map cleanly onto CIE, so revising from the wrong one means covering content that's never examined, or missing content that is.

Check your specification code before you start. It's usually printed on your past papers, or your teacher can confirm it.

AQA A Level Biology Topics (7402)

AQA's specification (7402) (opens in a new tab) is organised into eight numbered topics, each building on biological concepts sequentially.

1. Biological Molecules

Covers the molecules that build living organisms such as: carbohydrates, proteins, and water. It also introduces ATP and inorganic ions.

Subtopics: 

• Monomers and polymers

• Carbohydrates

• Lipids

• Proteins (including enzymes)

• Nucleic acids

• ATP

• Water

• Inorganic ions

2. Cells

Covers cell structure, prokaryotic vs eukaryotic cells, microscopy, and virus structure. Also introduces mitosis, binary fission, membrane transport, and the immune system.

Subtopics:

• Cell structure

• Transport across cell membranes

• Cell recognition

• The immune system

3. Organisms Exchange Substances with Their Environment

This topic focuses on the mechanisms by which organisms exchange essential substances with their surroundings.

Subtopics:

• Surface area to volume ratio

• Gas exchange

• Digestion and absorption

• Mass transport

4. Genetic Information, Variation and Relationships Between Organisms

Students examine how genetic information is stored, expressed and inherited, and how variation and biodiversity arise. It also includes methods used to classify organisms and measure diversity.

Subtopics: 

• DNA, genes and chromosomes

• DNA and protein synthesis

• Genetic diversity from mutation or meiosis

• Genetic diversity and adaptation

• Species and taxonomy

• Biodiversity within a community

• Investigating diversity

5. Energy Transfers In and Between Organisms

This section is on capture, transfer, and use of energy in living organisms.

Subtopics: 

• Photosynthesis

• Respiration

• Energy and ecosystems

• Nutrient cycles

6. Organisms Respond to Changes in Their Internal and External Environments

This topic explores how organisms detect and respond to stimuli using nervous and hormonal systems.

Subtopics: 

• Detecting stimuli

• Nervous coordination

• Skeletal muscle contraction

• Homeostasis

7. Genetics, Populations, Evolution and Ecosystems

Students learn about inheritance patterns and the mechanisms of evolution. 

Subtopics:

• Inheritance

• Populations

• Evolution and speciation

• Populations in ecosystems

8. The Control of Gene Expression

This final topic investigates how gene expression is regulated and how gene technologies are used in medicine and research.

Subtopics: 

• DNA sequence alteration and protein structure

• Control of gene expression

• Genome projects

• Gene technologies

AQA A Level Biology Papers

Paper 1 and Paper 2 each make up 35% of the A Level and Paper 3 makes up 30%.

Paper 3 includes 25 marks for an extended essay chosen from two titles, alongside structured questions and critical analysis of experimental data.

Next step: Explore our AQA A Level Biology resources.

OCR A Level Biology Topics (H420)

OCR's specification (H420) (opens in a new tab) is split into six modules, the first covering practical skills that run throughout the course.

Module 1: Development of Practical Skills in Biology

This module focuses on the practical skills required for studying biology at A Level.

Subtopics:

• Practical skills assessed in a written examination

• Practical skills assessed in the Practical Endorsement

Module 2: Foundations in Biology

This module lays the groundwork for understanding the structure and function of cells and the molecules that make life possible.

Subtopics: 

• Cell structure

• Biological molecules

• Nucleotides and nucleic acids

• Enzymes

• Biological membranes

• Cell division

• Cellular organisation

Module 3: Exchange and Transport

This module focuses on the need for specialised exchange surfaces and transport systems in multicellular organisms

Subtopics: 

• Exchange surfaces,

• Transport in animals

• Transport in plants

Module 4: Biodiversity, Evolution and Disease

This module explores the diversity of life, how it is classified and measured, and the mechanisms behind evolution.

Subtopics: 

• Communicable diseases and the immune system

• Biodiversity

• Classification and evolution

Module 5: Communication, Homeostasis and Energy

Students learn how organisms detect and respond to internal and external changes, focusing on homeostasis, neuronal and hormonal communication, and muscle physiology.

Subtopics: 

• Communication and homeostasis

• Excretion

• Neuronal communication

• Hormonal communication

• Plant and animal responses

• Photosynthesis

• Respiration

Module 6: Genetics, Evolution and Ecosystems

This final module covers genetic control, inheritance patterns, biotechnology and ecosystem dynamics.

Subtopics: 

• Cellular control

• Patterns of inheritance

• Manipulating genomes

• Cloning and biotechnology

• Ecosystems

• Populations

• Sustainability

OCR A Level Biology Papers

Papers 1 and 2 each count for 37% of the A Level and Paper 3 counts for 26%.

Next step: Explore our OCR A Level Biology resources.

Edexcel SNAB A Level Biology Topics (9BN0)

Edexcel's Salters-Nuffield specification (SNAB, 9BN0) (opens in a new tab) is context-led. Instead of grouping content by biological theme, it teaches concepts through real-world scenarios.

1. Lifestyle, Health and Risk

This topic explores lifestyle factors and how they affect our health. It covers:

• Cardiovascular disease risk

• Heart structure

• The cardiac cycle

• Blood vessels

• Blood clotting

• Evaluating health data

2. Genes and Health

Using the context of cystic fibrosis, this topic focuses on cell membranes and transport mechanisms. It covers: 

• Transport

• Gas exchange

• Enzyme function

• DNA and RNA structure

• Protein synthesis

• Genetic screening

3. Voice of the Genome

This topic considers how a single fertilised egg can develop into a complex multicellular organism. It covers: 

• Eukaryotic and prokaryotic cell structure

• Mitosis

• Meiosis

• Gamete structure

• Fertilisation

• Differential gene expression

• Stem cells

• Epigenetics

4. Biodiversity and Natural Resources

This topic considers how biodiversity is measured and compared, and how species show adaptation to their environment. It covers: 

• Biodiversity measurement

• Adaptation

• The Hardy–Weinberg equation

• Classification

• Plant cell structure

• Drug development

• Conservation strategies

5. On the Wild Side

This ecology-based topic looks at the role of photosynthesis in supporting ecosystems, and at the flow of energy through trophic levels. It covers:

• Photosynthesis

• Energy flow through trophic levels

• Primary productivity

• Climate change effects

• Succession

• Speciation

6. Immunity, Infection and Forensics

This topic combines immunology with forensic science. It covers:

• Pathogens

• Immune defences

• DNA profiling

• Time of death estimation

• Decomposition

• Antibiotic resistance

7. Run for Your Life

This topic explores how the body responds to physical activity. It covers:

• Muscle structure and contraction

• Aerobic and anaerobic respiration

• Heart rate regulation

• Performance-enhancing drugs

8. Grey Matter

This topic explores the structure and function of the nervous system. It covers: 

• Nerve impulses

• Synaptic transmission

• Brain structure

• Habituation

• Plant hormone IAA

• Genome sequencing

• Genetic modification

Edexcel SNAB A Level Biology Papers

Each paper is worth 33.3% of the A Level. Synoptic questions can draw on two or more topics, and Paper 3 includes a section based on a pre-released scientific article.

Next step: Explore our Edexcel SNAB A Level Biology resources.

CIE A Level Biology Topics (9700)

Cambridge International's specification (9700) (opens in a new tab) is divided into 19 topics.

1. Cell Structure

This topic introduces the basic unit of life - the cell. 

Students learn to distinguish between prokaryotic and eukaryotic cells, identify organelles and their functions, and understand the use of microscopes. The topic also addresses viruses as non-cellular structures.

2. Biological Molecules

Students explore key organic molecules, such as carbohydrates, lipids and proteins, examining how their molecular structures relate to function. 

Water and its properties are studied as a vital biological solvent. The topic also covers qualitative food tests to identify biological molecules.

3. Enzymes

This topic focuses on enzyme structure and function, including the lock-and-key and induced fit models. 

Students investigate how temperature, pH and other variables influence enzyme activity, and learn how enzymes are used in industrial and medical contexts, including immobilisation.

4. Cell Membranes and Transport

Students study the fluid mosaic model of membrane structure and the mechanisms by which substances move in and out of cells. 

These include diffusion, osmosis, active transport and endocytosis/exocytosis. Cell signalling and the importance of membrane proteins are also explored.

5. The Mitotic Cell Cycle

This topic explains how eukaryotic cells grow and divide through the mitotic cell cycle, including interphase, mitosis, and cytokinesis. 

Students study chromosome structure, the role of telomeres, and the function of stem cells. The consequences of uncontrolled cell division, such as tumour formation, are also introduced. 

6. Nucleic Acids and Protein Synthesis

Students explore the structure and roles of DNA and RNA in the storage and expression of genetic information. 

The processes of DNA replication, transcription and translation are covered, alongside the universal nature of the genetic code and the impact of mutations on protein function.

7. Transport in Plants

This topic explores how flowering plants transport water, mineral ions, and organic compounds within vascular tissue. 

Students examine the structure and function of xylem and phloem, the processes of transpiration and translocation, and adaptations that help reduce water loss.

8. Transport in Mammals

Focusing on the mammalian circulatory system, students study blood vessels, the structure and function of the heart, tissue fluid formation, and the role of blood in transporting oxygen and carbon dioxide. 

The structure and function of haemoglobin and the Bohr effect are also included.

9. Gas Exchange

This topic looks at the human gas exchange system, including lungs, bronchi, alveoli and associated tissues. 

Students learn how the structure of these components relates to function and how gases are exchanged between air and blood.

10. Infectious Diseases

Students investigate pathogens and their modes of transmission. Four major diseases - cholera, malaria, TB, and HIV/AIDS - are explored, in terms of cause, spread, prevention and control. The topic also includes antibiotic function and resistance.

11. Immunity

This topic outlines the immune response, including the roles of phagocytes, antigens, lymphocytes and antibodies. 

It also covers active and passive immunity, monoclonal antibodies, vaccination strategies, and how vaccines help control infectious diseases.

12. Energy and Respiration

Students study ATP as the universal energy currency, and examine the biochemical steps of aerobic and anaerobic respiration. 

Practical work reinforces these concepts through investigation of respiration rates.

13. Photosynthesis

Students study the structure of chloroplasts and the role of photosynthetic pigments, including chlorophyll and accessory pigments, in capturing light. 

The light-dependent and light-independent reactions are covered in detail, along with the factors that affect the rate of photosynthesis. 

Practical investigations help reinforce understanding of limiting factors. 

14. Homeostasis

Students learn about kidney structure and osmoregulation, blood glucose regulation, and cell signalling via hormones. The concept of negative feedback is central to these processes, allowing the body to detect and correct deviations from normal conditions.

The topic also includes plant responses to water stress and the role of guard cells and abscisic acid in stomatal regulation.

15. Control and Coordination

This topic explores nervous and hormonal coordination in animals and plants. Students study nerve impulses, synaptic transmission, muscle contraction, and the comparison of nervous vs endocrine systems. 

Plant responses, such as the Venus fly trap and plant hormone action, are also included.

16. Inheritance

This topic begins with meiosis as the basis of genetic variation and introduces the principles of monohybrid and dihybrid inheritance, including codominance, sex linkage and epistasis. 

Students learn how to analyse genetic crosses, interpret pedigree diagrams, and apply the chi-squared test to genetic data. 

The topic also covers the role of mutations and explores how genes are regulated

17. Selection and Evolution

This topic explains how variation within populations provides the basis for natural and artificial selection. 

Students learn how different types of selection, the founder effect, and genetic drift contribute to changes in allele frequencies and the formation of new species over time. 

The Hardy–Weinberg principle is used, and students consider the role played by DNA data in the study of evolution.

18. Classification, Biodiversity and Conservation

This topic includes the principles of taxonomy, modern classification using molecular evidence, and the importance of biodiversity at genetic, species, and ecosystem levels. 

It also addresses threats to biodiversity and outlines conservation strategies such as habitat management, captive breeding, and seed banks.

19. Genetic Technology

Students learn how DNA can be amplified, sequenced, and analysed using techniques such as PCR, electrophoresis, and gene probes. 

Applications include genetic modification, gene therapy, and the production of transgenic organisms. Ethical issues surrounding the use of genetic technologies are also considered. 

CIE A Level Biology Papers

• Paper 1 makes up 15.5% of the A Level

• Paper 2 makes up 23%

• Paper 3 makes up 11.5%

• Paper 4 makes up 38.5%

• Paper 5 makes up 11.5%

Next step: Explore our CIE A Level Biology resources.

How to Use Topic Lists for Revision

Find your specification table and turn the topics into a working revision checklist.

Go through each topic and mark it as confident, needs work, or not yet covered.

Start your first revision pass on anything marked "not yet covered." These are your highest-risk gaps, since you haven't engaged with the content at all yet.

Once you've covered everything once, prioritise "needs work" topics. Past paper questions and targeted practice pay off most here.

Revisit "confident" topics every so often too. Content from early in the course fades if you don't return to it, especially anything from Year 12.

Cross-check your topic list against your paper structure. If you know Paper 3 draws on all topics but Paper 1 only covers the first half of the spec, you can weight your revision time accordingly as exams approach.

Frequently Asked Questions

Do I need to revise all A Level Biology topics for the exam?

Yes. Every topic on your specification is examinable, and any of them can come up in your exam papers. Some topics carry more marks than others across a typical paper, but none are guaranteed to be skipped.

Are these topics the same across all exam boards?

No. While there's overlap in core biological concepts like cell structure, genetics, and respiration, each board organises and weights topics differently. AQA and OCR structure content thematically, while Edexcel SNAB teaches through real-world contexts. Always revise from the topic list for your specific board.

How do I know which topics I struggle with most?

Past papers are the most reliable way to find out. Work through topic-based exam questions and track where you consistently lose marks, then cross-reference against the topic tables above.

Do all topics come up in every exam paper?

Not always. Some boards split content across papers by topic number, like AQA and Edexcel SNAB. Others, like OCR and CIE, mix modules or topics across multiple papers within the same exam series. Check the paper breakdown for your specification before assuming a topic won't appear.

Use Save My Exams To Grow Your Grade

Knowing your exam board and specification code is the first step in effective A Level Biology revision.

Once you've mapped out what's examinable, you can stop guessing and start building a revision plan that actually targets the content in your papers.

Use the topic lists above as your starting point, then put Save My Exams' smart tools to work. Target Test generates a personalised practice test built around your exact specification:

• AQA A Level Biology Target Test

• OCR A Level Biology Target Test

• Edexcel SNAB A Level Biology Target Test

• CIE A Level Biology Target Test

You can choose the topics, question types, and difficulty, so every practice session hits a learning gap instead of covering ground you've already nailed.

Once you've completed a test, Smart Mark marks your answers instantly against exam-board-aligned criteria, showing you precisely where the marks were won and lost.

Used together, they turn the topic breakdown above from a static list into a revision cycle: test, mark, identify the gap, target it again.

Good luck with your exams.

Explore our A Level Biology resources.

References

AQA A Level Biology Specification (opens in a new tab)

OCR A Level Biology Specification (opens in a new tab)

Edexcel Salters-Nuffield A Level Biology Specification (opens in a new tab)

CIE A Level Biology Specification (opens in a new tab)