OCR A-LEVEL BIOLOGY
Biology A-Level
Questions Students
Struggle With Most
& How to Answer Them
Covering all major topics · Exam-ready answers · Clear explanations
30 8 50+ 100%
Pages Topics Questions Exam-Focused
For personal study use · Ideal for Year 12 & 13 revision
,OCR A-Level Biology | Questions & Answers 2
Table of Contents
# Topic Page
1 Cell Biology & Microscopy 4
2 Biological Molecules 7
3 Enzymes 10
4 Cell Transport & Membranes 13
5 Genetics & DNA 16
6 Photosynthesis & Respiration 19
7 Evolution, Biodiversity & Classification 23
8 Ecology & Ecosystems 26
— Quick-Fire Revision Checklist 29
— Common Mistakes Summary 30
This guide tackles the exact questions that trip students up in OCR A-Level Biology exams. Every
question is paired with a full model answer and an examiner tip so you know exactly what to write
— and what to avoid. Work through each section at your own pace, then use the checklist at the
back to track what you have nailed and what still needs work.
OCR A-Level Biology Guide Study Smart · Revise Right
, OCR A-Level Biology | Questions & Answers 3
CHAPTER 1
Cell Biology & Microscopy
Why students struggle:
Students often mix up prokaryotic and eukaryotic cells, forget magnification formulas, or cannot explain
what they actually see in micrographs. These questions test precision.
Key Terms
Prokaryote A cell that has no membrane-bound nucleus or organelles. E.g. bacteria.
Eukaryote A cell that has a true membrane-bound nucleus and organelles. E.g. animal, plant,
fungal cells.
Resolution The ability to distinguish two points as separate — determines detail quality.
Magnification How many times larger the image is than the real object.
Cell fractionation A lab technique to separate organelles by spinning them at different speeds.
Questions & Model Answers
Q1 (3
State three differences between a prokaryotic cell and a eukaryotic cell.
marks)
✔ MODEL 1. Prokaryotic cells have no membrane-bound nucleus; eukaryotic cells do. 2.
ANSWER Prokaryotic cells have smaller (70S) ribosomes; eukaryotic cells have larger (80S)
ribosomes. 3. Prokaryotic cells have no membrane-bound organelles (e.g.
mitochondria); eukaryotic cells do.
★ EXAMINER Each difference must be a genuine contrast — do not just say 'no nucleus'. Say 'no
TIP membrane-bound nucleus' to get the mark.
Q2 (2 An image of a cell is 30 mm wide. The actual cell is 0.03 mm wide. Calculate the
marks) magnification.
✔ MODEL Magnification = Image size ÷ Actual size = 30 mm ÷ 0.03 mm = ×1000 The
ANSWER magnification is ×1000.
★ EXAMINER Always show working. If your final answer is wrong but the formula and working are correct, you
TIP can still earn a mark.
Q3 (4 Describe how you would use cell fractionation to isolate mitochondria from
marks) liver cells.
OCR A-Level Biology Guide Study Smart · Revise Right
Biology A-Level
Questions Students
Struggle With Most
& How to Answer Them
Covering all major topics · Exam-ready answers · Clear explanations
30 8 50+ 100%
Pages Topics Questions Exam-Focused
For personal study use · Ideal for Year 12 & 13 revision
,OCR A-Level Biology | Questions & Answers 2
Table of Contents
# Topic Page
1 Cell Biology & Microscopy 4
2 Biological Molecules 7
3 Enzymes 10
4 Cell Transport & Membranes 13
5 Genetics & DNA 16
6 Photosynthesis & Respiration 19
7 Evolution, Biodiversity & Classification 23
8 Ecology & Ecosystems 26
— Quick-Fire Revision Checklist 29
— Common Mistakes Summary 30
This guide tackles the exact questions that trip students up in OCR A-Level Biology exams. Every
question is paired with a full model answer and an examiner tip so you know exactly what to write
— and what to avoid. Work through each section at your own pace, then use the checklist at the
back to track what you have nailed and what still needs work.
OCR A-Level Biology Guide Study Smart · Revise Right
, OCR A-Level Biology | Questions & Answers 3
CHAPTER 1
Cell Biology & Microscopy
Why students struggle:
Students often mix up prokaryotic and eukaryotic cells, forget magnification formulas, or cannot explain
what they actually see in micrographs. These questions test precision.
Key Terms
Prokaryote A cell that has no membrane-bound nucleus or organelles. E.g. bacteria.
Eukaryote A cell that has a true membrane-bound nucleus and organelles. E.g. animal, plant,
fungal cells.
Resolution The ability to distinguish two points as separate — determines detail quality.
Magnification How many times larger the image is than the real object.
Cell fractionation A lab technique to separate organelles by spinning them at different speeds.
Questions & Model Answers
Q1 (3
State three differences between a prokaryotic cell and a eukaryotic cell.
marks)
✔ MODEL 1. Prokaryotic cells have no membrane-bound nucleus; eukaryotic cells do. 2.
ANSWER Prokaryotic cells have smaller (70S) ribosomes; eukaryotic cells have larger (80S)
ribosomes. 3. Prokaryotic cells have no membrane-bound organelles (e.g.
mitochondria); eukaryotic cells do.
★ EXAMINER Each difference must be a genuine contrast — do not just say 'no nucleus'. Say 'no
TIP membrane-bound nucleus' to get the mark.
Q2 (2 An image of a cell is 30 mm wide. The actual cell is 0.03 mm wide. Calculate the
marks) magnification.
✔ MODEL Magnification = Image size ÷ Actual size = 30 mm ÷ 0.03 mm = ×1000 The
ANSWER magnification is ×1000.
★ EXAMINER Always show working. If your final answer is wrong but the formula and working are correct, you
TIP can still earn a mark.
Q3 (4 Describe how you would use cell fractionation to isolate mitochondria from
marks) liver cells.
OCR A-Level Biology Guide Study Smart · Revise Right
