AQA Biology A-Level
Exam Questions That Keep
Coming Back – and How
to Answer Them
A visual, student-friendly revision guide
covering all 8 examinable topics
Cell Biology Genetics Ecology Biochemistry
Physiology Evolution Disease Homeostasis
Ideal for Year 12 & 13 • Papers 1, 2 & 3 • All Exam Boards using AQA Spec
,AQA Biology A-Level | Exam Questions & Model Answers Page 1
CHAPTER
Table of Contents
Chapter Topic Key Themes
1 Cell Biology & Microscopy Cell structure, transport, cell cycle
2 Biological Molecules Carbs, proteins, lipids, enzymes, DNA
3 Genetics & Inheritance DNA replication, meiosis, inheritance patterns
4 Photosynthesis Light-dependent, Calvin cycle, limiting factors
5 Respiration Glycolysis, Krebs, oxidative phosphorylation
6 Ecosystems & Ecology Energy flow, nutrient cycles, populations
7 Homeostasis & The Nervous System Neurones, synapses, hormones
8 Immunity & Disease Immune response, vaccines, pathogens
9 Evolution & Biodiversity Natural selection, speciation, classification
10 Exam Technique & Marking Tips Command words, mark schemes, structure
This guide targets the most frequently tested AQA Biology A-Level exam questions. Each chapter explains the
concept in plain language, shows you the exact points examiners want to see, and gives you model answers with
mark-scheme breakdowns.
Study smart • Understand the mark scheme • Practice under timed conditions
, AQA Biology A-Level | Exam Questions & Model Answers Page 2
CHAPTER 1
Cell Biology & Microscopy
Why This Topic Keeps Appearing
Cell biology underpins every other topic in A-Level Biology. The AQA mark schemes reward precision – examiners
want the right organelle, the right function, and the right description of transport mechanisms. Vague answers lose
marks even when students know the concept.
Fluid Mosaic Model – Cell Surface Membrane
Protein channel / carrier
Phospholipid head (hydrophilic)
Fatty acid tails (hydrophobic)
Phospholipid head (hydrophilic)
Top Exam Questions & Model Answers
■ Explain how the structure of the cell surface membrane allows selective permeability. (4 marks)
✓ The phospholipid bilayer has hydrophobic fatty acid tails in the centre – ions and polar molecules cannot pass
through freely.
✓ Hydrophilic phosphate heads face outwards and allow water to interact with the membrane surface.
✓ Protein channels (e.g. aquaporins) span the bilayer and provide a hydrophilic pore for specific ions/molecules.
✓ Carrier proteins use conformational changes to actively transport or facilitate diffusion of specific molecules.
■ Examiner tip: Mention both the bilayer AND the proteins – most 4-mark answers require both structural and functional
points.
■ Describe and explain the differences between prokaryotic and eukaryotic cells. (6 marks)
✓ Prokaryotic cells are smaller (typically 1–10 µm); eukaryotic cells are 10–100 µm.
✓ Prokaryotes have no membrane-bound nucleus; DNA is circular and found in the nucleoid region.
✓ Eukaryotes have membrane-bound organelles (mitochondria, ER, Golgi); prokaryotes do not.
✓ Prokaryotes have smaller ribosomes (70S) compared to eukaryotes (80S).
✓ Prokaryotes may have plasmids, a cell wall made of murein, and flagella.
✓ Eukaryotic cells have a cytoskeleton; prokaryotes do not.
■ Examiner tip: 6-mark questions need 6 distinct, specific points. Never write the same idea twice in different words.
Key Terms to Know Cold
Term Definition
Resolution The ability to distinguish between two points as separate objects
Magnification How many times larger an image is compared to the real object
Organelle A membrane-bound structure within a eukaryotic cell with a specific function
Fluid mosaic model Singer & Nicolson's model: a bilayer of phospholipids with embedded proteins that can move
laterally
Study smart • Understand the mark scheme • Practice under timed conditions
Exam Questions That Keep
Coming Back – and How
to Answer Them
A visual, student-friendly revision guide
covering all 8 examinable topics
Cell Biology Genetics Ecology Biochemistry
Physiology Evolution Disease Homeostasis
Ideal for Year 12 & 13 • Papers 1, 2 & 3 • All Exam Boards using AQA Spec
,AQA Biology A-Level | Exam Questions & Model Answers Page 1
CHAPTER
Table of Contents
Chapter Topic Key Themes
1 Cell Biology & Microscopy Cell structure, transport, cell cycle
2 Biological Molecules Carbs, proteins, lipids, enzymes, DNA
3 Genetics & Inheritance DNA replication, meiosis, inheritance patterns
4 Photosynthesis Light-dependent, Calvin cycle, limiting factors
5 Respiration Glycolysis, Krebs, oxidative phosphorylation
6 Ecosystems & Ecology Energy flow, nutrient cycles, populations
7 Homeostasis & The Nervous System Neurones, synapses, hormones
8 Immunity & Disease Immune response, vaccines, pathogens
9 Evolution & Biodiversity Natural selection, speciation, classification
10 Exam Technique & Marking Tips Command words, mark schemes, structure
This guide targets the most frequently tested AQA Biology A-Level exam questions. Each chapter explains the
concept in plain language, shows you the exact points examiners want to see, and gives you model answers with
mark-scheme breakdowns.
Study smart • Understand the mark scheme • Practice under timed conditions
, AQA Biology A-Level | Exam Questions & Model Answers Page 2
CHAPTER 1
Cell Biology & Microscopy
Why This Topic Keeps Appearing
Cell biology underpins every other topic in A-Level Biology. The AQA mark schemes reward precision – examiners
want the right organelle, the right function, and the right description of transport mechanisms. Vague answers lose
marks even when students know the concept.
Fluid Mosaic Model – Cell Surface Membrane
Protein channel / carrier
Phospholipid head (hydrophilic)
Fatty acid tails (hydrophobic)
Phospholipid head (hydrophilic)
Top Exam Questions & Model Answers
■ Explain how the structure of the cell surface membrane allows selective permeability. (4 marks)
✓ The phospholipid bilayer has hydrophobic fatty acid tails in the centre – ions and polar molecules cannot pass
through freely.
✓ Hydrophilic phosphate heads face outwards and allow water to interact with the membrane surface.
✓ Protein channels (e.g. aquaporins) span the bilayer and provide a hydrophilic pore for specific ions/molecules.
✓ Carrier proteins use conformational changes to actively transport or facilitate diffusion of specific molecules.
■ Examiner tip: Mention both the bilayer AND the proteins – most 4-mark answers require both structural and functional
points.
■ Describe and explain the differences between prokaryotic and eukaryotic cells. (6 marks)
✓ Prokaryotic cells are smaller (typically 1–10 µm); eukaryotic cells are 10–100 µm.
✓ Prokaryotes have no membrane-bound nucleus; DNA is circular and found in the nucleoid region.
✓ Eukaryotes have membrane-bound organelles (mitochondria, ER, Golgi); prokaryotes do not.
✓ Prokaryotes have smaller ribosomes (70S) compared to eukaryotes (80S).
✓ Prokaryotes may have plasmids, a cell wall made of murein, and flagella.
✓ Eukaryotic cells have a cytoskeleton; prokaryotes do not.
■ Examiner tip: 6-mark questions need 6 distinct, specific points. Never write the same idea twice in different words.
Key Terms to Know Cold
Term Definition
Resolution The ability to distinguish between two points as separate objects
Magnification How many times larger an image is compared to the real object
Organelle A membrane-bound structure within a eukaryotic cell with a specific function
Fluid mosaic model Singer & Nicolson's model: a bilayer of phospholipids with embedded proteins that can move
laterally
Study smart • Understand the mark scheme • Practice under timed conditions
