It can be hard to pick which topics you want to write about in your essay. The article below provides examples and tips to help you through this process. For a full overview of the Extended Essay, go to this previous blog post.

Background

The AQA Paper 3 Extended Essay is a 25-mark synoptic essay that appears at the end of Paper 3. You need to write an essay using one of the provided titles.

E.g.: “Write an essay on using DNA in science and technology”, or “Write an essay on the importance of membranes in the functioning of cells”.

There are different ways you can approach your essay, but to win marks you need to:

Present examples from different topic areas (numbered parts) of the specification
Link these topic areas to the main theme
Present the information at A-level standard, using correct terminology
Avoid irrelevant topics, irrelevant information, or factual errors

How Many Topic Areas Do I Need?

AQA say “several”, and suggest a minimum of 4. I would suggest you choose 5 or 6 from the specification. You need to spend a similar amount of time on each one.

Off-spec topics: to score 24-25/25, you would need to include a topic outside the A-level specification. But I always recommend students stay within spec. You don’t need to score so high to get an A* overall (aiming for 18/25 is fine!), and many students attempting off-spec topics fail due to lack of depth and scientific terminology. Using something you heard on a podcast isn’t enough; you need to present it at A-level standard or above.

Example Essay Title and possible Topic Areas

The examiners give feedback after the exams explaining which topic areas they consider appropriate for each title. It’s worth looking at some examples to get an idea of how it works. Here’s one to start:

Example extended essay title:
Write an essay on the importance of membranes in the functioning of cells

Possible topic areas:
• 3.1.3 Lipids (phospholipids)
• 3.2.1.1 Structure of eukaryotic cells
• 3.2.1.2 Structure of prokaryotic cells
• 3.2.2 All cells arise from other cells (nuclear membrane breakdown in mitosis)
• 3.2.3 Transport across cell membranes
• 3.2.4 Cell recognition and the immune system
• 3.3.1 Surface area to volume ratio
• 3.3.2 Gas exchange
• 3.3.3 Digestion and absorption
• 3.4.2 DNA and protein synthesis
• 3.5.1 Photosynthesis
• 3.5.2 Respiration
• 3.6.1.2 Receptors
• 3.6.2.1 Nerve impulses
• 3.6.2.2 Synaptic transmission
• 3.6.3 Skeletal muscles are stimulated to contract by nerves and act as effectors
• 3.6.4.2 Control of blood glucose concentration
• 3.6.4.3 Control of blood water potential
• 3.8.2.2 Regulation of transcription and translation

Having a lot of choice is great as you can pick areas where you are strong. But remember to spread your choice through the whole specification - avoid picking similar/neighbouring sub-sections.

Can you work out how each of the above topics areas could relate to the theme? How are they important? It’s crucial to approach each area with the theme in mind, rather than just writing about that topic area in general. Larger topics may include irrelevant information that you need to avoid.

But you don’t need to link the topics to each other (even though it might sound like that on the marking information). You need only to link them to the main theme.

How to think of potential Topic Areas

It can be difficult to think broadly under exam pressure, so here’s a trick I suggest students try:

Think your way through the Kingdoms of Life. Can you think of illustrative examples from each Kingdom? (Ok, maybe not protists.)
Think your way through different scales. From single molecules → macromolecule → organelle → cells → tissue → organ → organ system → individual → populations → community → ecosystem.

Scribble down all the ideas you can think of for the essay titles, then see which list looks most likely and focus on picking from that.

By choosing topics with a variety of Kingdoms and Scales, you can get both breadth and depth into your selection. You want to pick topic areas that are as spread out as possible in the specification. Just make sure they will all serve the essay title!

Practice with Past Papers

Practice choosing topics! Just reading the list won’t help you - it’ll just make you think it’s easier than it is. Your titles will be different to these, so remembering doesn’t help either. You need to practice the process to acquire this skill.

Look at each title, write a list of potential topics, and then check these against the examiners’ lists shown below. Do this a few times and you will start getting a feel for how to think your way through the spec.

For each topic, think about what information would be relevant to the title, and why the topic is important to the theme. You will need to write about both of these to get the marks.

Recent Past Paper Essay topics:

Phosphorus-containing substances and their importance in biological systems.
The mechanisms and importance of transport within organisms.
The importance of interactions between organisms and their environment.
The importance of shapes fitting together in cells and organisms.
How bacteria can affect the lives of humans and other organisms.
A cycle is a biological pathway or process in which the end product of one cycle becomes the starting point for the next cycle. Write an essay on cycles in biology.
Carbon dioxide may affect organisms directly or indirectly. Write an essay to describe and explain these effects.
Polymers have different structures. They also have different functions. Write an essay to describe how the structures of different polymers are related to their functions.
Using DNA in science and technology.
The importance of membranes in the functioning of cells.

More AQA Paper 3 Extended Essay Titles here

Examiners’ expected topic areas:

Below are the same essay questions numbered in the same way. Each has a list of topic areas that examiners considered it appropriate to use. Remember your chosen topic areas should be from very different parts of the specification, not all from the same section.

Phosphorus-containing substances and their importance in biological systems.
3.1.3 Lipids
3.1.5.1 Structure of DNA and RNA
3.1.5.2 DNA replication
3.1.6 ATP
3.1.8 Inorganic ions
3.2.1.1 Structure of eukaryotic cells
3.2.2 All cells arise from other cells
3.2.3 Transport across cell membranes
3.3.3 Digestion and absorption
3.4.1 DNA, genes and chromosomes
3.4.2 DNA and protein synthesis
3.4.3 Genetic diversity can arise as a result of mutation or during meiosis
3.4.4 Genetic diversity and adaptation
3.4.7 Investigating diversity
3.5.1 Photosynthesis
3.5.2 Respiration
3.5.4 Nutrient cycles
3.6.2.1 Nerve impulses
3.6.2.2 Synaptic transmission
3.6.3 Skeletal muscles
3.6.4.2 Control of blood glucose concentration (cyclic AMP)
3.6.4.3 Control of blood water potential
3.8.1 Alteration of the sequence of bases in DNA can alter the structure of proteins
3.8.2.1 Most of a cell’s DNA is not translated
3.8.2.2 Regulation of transcription and translation
3.8.3 Using genome projects
3.8.4.1 Recombinant DNA technology
The mechanisms and importance of transport within organisms.
3.1.3 Phospholipids
3.1.4 Proteins
3.1.6 ATP
3.1.7 Water
3.2.1.1 Structure of eukaryotic cells
3.2.2 All cells arise from other cells
3.2.3 Transport across cell membranes
3.2.4 Cell recognition and the immune system
3.3.1 Surface area to volume ratio
3.3.2 Gas exchange
3.3.3 Digestion and absorption
3.3.4.1 Mass transport in animals
3.3.4.2 Mass transport in plants
3.4.2 DNA and protein synthesis
3.4.3 Genetic diversity can arise as a result of mutation or during meiosis
3.5.1 Photosynthesis
3.5.2 Respiration
3.6.1.1 Survival and response (IAA)
3.6.1.2 Receptors
3.6.1.3 Control of heart rate
3.6.2.1 Nerve impulses
3.6.2.2 Synaptic transmission
3.6.3 Skeletal muscles
3.6.4.1 Principles of homeostasis and negative feedback
3.6.4.2 Control of blood glucose concentration
3.6.4.3 Control of blood water potential
3.8.1 Alteration of the sequence of bases in DNA can alter the structure of proteins
3.8.2.2 Regulation of transcription and translation
3.8.2.3 Gene expression and cancer
The importance of interactions between organisms and their environment.
3.1.2 Carbohydrates (the relationship of structure to function of glycogen, starch and cellulose in animal cells and plant cells)
3.1.4.2 Many proteins are enzymes (enzyme inhibitors)
3.1.7 Water
3.2.3 Transport across cell membranes
3.2.4 Cell recognition and the immune system
3.3.1 Surface area to volume ratio
3.3.2 Gas exchange
3.3.3 Digestion and absorption
3.3.4.1 Mass transport in animals
3.3.4.2 Mass transport in plants
3.4.4 Genetic diversity and adaptation
3.4.5 Species and taxonomy (courtship)
3.4.6 Biodiversity within a community
3.5.1 Photosynthesis
3.5.3 Energy and ecosystems
3.5.4 Nutrient cycles
3.6.1.1 Survival and response
3.6.1.2 Receptors
3.6.1.3 Control of heart rate
3.6.2.1 Nerve impulses
3.6.2.2 Synaptic transmission (effects of drugs)
3.6.4.1 Principles of homeostasis and negative feedback
3.6.4.2 Control of blood glucose concentration
3.6.4.3 Control of blood water potential
3.7.1 Inheritance
3.7.3 Evolution may lead to speciation
3.7.4 Populations in ecosystems
3.8.1 Alteration of the sequence of bases in DNA can alter the structure of proteins
3.8.2.1 Most of a cell’s DNA is not translated
3.8.2.2 Regulation of transcription and translation
3.8.2.3 Gene expression and cancer
The importance of shapes fitting together in cells and organisms.
Proteins & Enzymes
3.1.2 Enzyme properties and digestion
3.1.2 Protein structure
3.1.3 Plasma membrane structure and cell transport
3.1.6 Antigens, antibodies, B cells & T cells
3.1.6 Vaccines
Nucleic Acids
3.2.2 Structure of DNA
3.2.2 DNA Replication (not PCR)
3.5.7 Transcription & translation
3.5.8 Transcriptional factors, oestrogen, siRNA
3.5.8 Restriction enzymes
Physiology
3.2.4 Haemoglobin
3.5.2 Action potentials & synaptic transmission
3.5.3 Muscle contraction
3.5.4 Control of blood glucose concentration
How bacteria can affect the lives of humans and other organisms.
Bacteria & Disease
3.1.1 Pathogens
3.2.10 Resistance to antibiotics
Ecological Importance
3.4.6 Nitrogen cycle
3.4.6 Eutrophication
Making Use of Bacteria
3.5.8 Use of bacterial enzymes e.g. restriction endonuclease, DNA polymerase for PCR
3.5.8 Use of bacterial plasmids e.g. in vivo gene cloning, genetically-modified crops, gene therapy
3.5.8 Use of bacteria to produce useful chemicals
A cycle is a biological pathway or process in which the end product of one cycle becomes the starting point for the next cycle. Write an essay on cycles in biology.
Ecological cycles
4.6 Nutrient cycles
Biochemical cycles
1.2 Enzyme action
4.2 Synthesis of ATP from ADP
4.3 Light-independent reaction
4.4 The Krebs cycle
Physiological and genetic cycles
1.4 The mechanism of breathing
1.5 The cardiac cycle
2.5 The cell cycle
5.3 Muscle contraction
Carbon dioxide may affect organisms directly or indirectly. Write an essay to describe and explain these effects.
Carbon dioxide affects the physiology of organisms
1.4 Pulmonary ventilation and the mechanism of breathing
4.3 Light-independent reaction of photosynthesis. Limiting factors
5.1 Role of chemoreceptors in controlling heart rate
The direct effects of increasing carbon dioxide concentration
4.6 Respiration, photosynthesis and human activity giving rise to short-term fluctuations and long-term change. Yield of crop plants
Indirect effects of increasing carbon dioxide concentration
4.6 Distribution of animals and plants
1.2 Effect of temperature on enzymes
Polymers have different structures. They also have different functions. Write an essay to describe how the structures of different polymers are related to their functions.
3.1.1 Monomers and polymers
3.1.2 Carbohydrates
3.1.4 Proteins
3.1.5 Nucleic acids
3.2.3 transport across membranes
3.2.4 Cell recognition and the immune system
3.3.3 Digestion and absorption
3.4.1 DNA, genes and chromosomes
Using DNA in science and technology.
DNA and classification
2.2 Structure of DNA
2.3 Differences in DNA lead to genetic diversity
2.9 Comparison of DNA base sequences
Genetic engineering and making useful substances
2.5 Plasmids
5.8 The use of recombinant DNA to produce transformed organisms that benefit humans
Other uses of DNA
2.5 Cell cycle and treatment of cancer
5.8 Gene therapy; Medical diagnosis and the treatment of human disease; The use of DNA probes to screen patients for clinically important genes.
The importance of membranes in the functioning of cells.
3.1.3 Lipids (phospholipids)
3.2.1.1 Structure of eukaryotic cells
3.2.1.2 Structure of prokaryotic cells
3.2.2 All cells arise from other cells (nuclear membrane breakdown in mitosis)
3.2.3 Transport across cell membranes
3.2.4 Cell recognition and the immune system
3.3.1 Surface area to volume ratio
3.3.2 Gas exchange
3.3.3 Digestion and absorption
3.4.2 DNA and protein synthesis
3.5.1 Photosynthesis
3.5.2 Respiration
3.6.1.2 Receptors
3.6.2.1 Nerve impulses
3.6.2.2 Synaptic transmission
3.6.3 Skeletal muscles are stimulated to contract by nerves and act as effectors
3.6.4.2 Control of blood glucose concentration
3.6.4.3 Control of blood water potential
3.8.2.2 Regulation of transcription and translation