OCR A 2.1.1 · 20 written questions · 46 marks · about 55 minutes · marked as you go
This free quiz has 20 written exam questions on cell structure and microscopy, all taken from OCR A Level Biology A papers (AS and A level, 2018 to 2025). Short answers and calculations mark themselves. For longer answers you write your answer, then tick off the OCR mark-scheme points you made, so you see exactly where the marks are. The quiz works through OCR A spec 2.1.1, from choosing and using microscopes to the organelles inside eukaryotic cells and how prokaryotic cells differ.
What the quiz covers (OCR A spec 2.1.1)
Microscopes and resolution (2.1.1(a)(f)): telling light, TEM, SEM and confocal images apart, comparing resolution and why small cells are hard to see
Slides and staining (2.1.1(b)(c)): preparing a wet mount, calibrating an eyepiece graticule, choosing stains and why differential staining matters
Biological drawings (2.1.1(d)): judging a student's drawing against the photomicrograph it came from
Magnification (2.1.1(e)): actual size and magnification calculations with unit conversions and significant figures
Organelles and micrographs (2.1.1(g)(h)): identifying components on an electron micrograph, membrane-bound organelles and linking organelles to a cell's job
Protein secretion and the cytoskeleton (2.1.1(i)(j)): the route from RER to Golgi to vesicle, and what the cytoskeleton does
Prokaryotic and eukaryotic cells (2.1.1(k)): ribosomes, pili, cell walls and flagella
How to use it
Write every answer in full, as you would in the exam: the mark for each question is shown, so you know how much to write. When you self-mark, only tick a point if your answer clearly makes it, then read the examiner's tip under each question. Your progress is saved on your device, so you can do it in two sittings, and at the end you can retry just the questions where you dropped marks.
Prefer multiple choice? Try the 16-question Cell Structure multiple choice quiz first.
Open the Cell Structure and Microscopy quiz in a new tab (easier on a phone)
Where students lose marks (from OCR examiners' reports and mark schemes)
Each point below is followed by wording that gained marks.
Measure in mm, then convert: Students measure the image in cm and then multiply by 1000 to get µm, so the answer is out by a factor of 10.
✔ Gains credit: Measure in millimetres, multiply by 1000 to get micrometres, divide by the magnification, then round to the same number of significant figures as the measurement (or one more).
Say what the stain lets you see: Answers about staining say it shows 'components' or 'structures', and rarely mention contrast, which is too vague to score.
✔ Gains credit: Staining increases contrast so that different cell types and named organelles (e.g. the nucleus) can be seen and told apart.
Nucleolus, not nucleus: On electron micrographs the dark, dense region inside the nucleus is often labelled 'nucleus'.
✔ Gains credit: Nucleolus (the dense region within the nucleus).
Bacteria are small: Students say bacteria are hard to see because of the microscope's resolution, without mentioning the cells at all, or claim it is because they have no nucleus to stain.
✔ Gains credit: Bacterial cells are smaller (their size is close to the wavelength of visible light).
Don't divide by the objective lens: After a correct graticule calculation, students divide their answer by the objective lens magnification, even though the graticule was calibrated for that lens.
✔ Gains credit: Calibrate one graticule division with the stage micrometer, count the divisions across the cell and multiply: that is already the real size.
Plant cells have 80S ribosomes: Many think onion root cells contain 70S ribosomes and pili, mixing up eukaryotic and prokaryotic features.
✔ Gains credit: Onion root cells contain mitochondria and cellulose cell walls but no chloroplasts, pili or 70S ribosomes in the cytoplasm.
No smears for pond water: To improve a pond water slide, students suggest a smear or a dye; a smear dries the sample out and a stain isn't needed to see organisms.
✔ Gains credit: Use a pipette to put a single drop on the slide, add a coverslip and make sure there are no air bubbles.
Peptidoglycan, spelled carefully: Bacterial cell walls are often said to be made of chitin or cellulose, and peptidoglycan is frequently misspelt.
✔ Gains credit: Peptidoglycan (murein).
Keep practising
Try the Cell Structure multiple choice quiz, the Microscopy and Magnification quiz, the Water, Carbohydrates and Lipids written quiz, or browse all our OCR A Level Biology quizzes. Our OCR A masterclasses (Year 12 on Wednesdays at 5.15pm, Year 13 on Tuesdays at 6.30pm) work through real exam questions on one topic each week.
Questions, mark schemes and examiners' report extracts © OCR.