A-LEVEL BIOLOGY – OCR JUNE 2026

A-LEVEL BIOLOGY – OCR
JUNE 2026

1. What is a light microscope used for?
A) Observing only dead specimens
B) Observing only living specimens
C) Observing living and dead specimens ✅
D) Observing atomic structures



2. Which of the following are pros and cons of a light microscope?
A) Pros: Expensive; Cons: Limited magnification
B) Pros: Cheap, portable, easy to use, can study living specimens; Cons: Limited magnification,
poor resolution ✅
C) Pros: High resolution; Cons: Kills cells
D) Pros: Uses electrons; Cons: Complex operation



3. What is a laser scanning confocal microscope used for?
A) Viewing the cell surface
B) Producing 3D images at different depths with high contrast and resolution ✅
C) Observing living tissue movement
D) Viewing only dead cells



4. What is a transmission electron microscope (TEM) used for?
A) Viewing surface structures
B) Observing internal ultrastructure of cells under high magnification and resolution ✅
C) Studying living tissue
D) Measuring wavelength of light



5. What is a scanning electron microscope (SEM) used for?
A) Observing the surface of objects under high magnification and resolution ✅


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,B) Viewing the nucleus
C) Seeing living cells
D) Detecting molecules in blood



6. Which of the following best describes the pros and cons of an electron microscope?
A) Pros: High magnification and resolution; Cons: Specimen must be dead, expensive, large,
needs skill ✅
B) Pros: Portable; Cons: Low resolution
C) Pros: Cheap; Cons: Uses light
D) Pros: Small; Cons: Poor magnification



7. What is the main difference between a TEM and an SEM?
A) TEM bounces electrons; SEM transmits them
B) TEM sends electrons through the specimen; SEM bounces electrons off the surface ✅
C) Both work exactly the same
D) TEM uses light, SEM uses electrons



8. What is the main difference between light and electron microscopes?
A) Both use light
B) Light microscope uses light and lenses; electron microscope uses electrons and magnets ✅
C) Light microscope uses magnets; electron microscope uses light
D) Both observe only dead specimens



9. What is an eyepiece graticule?
A) A slide used for calibration
B) A small ruler fitted to the eyepiece, used for measuring specimens after calibration ✅
C) A type of magnifying lens
D) The base of the microscope



10. What is a stage micrometer?
A) A scale on the eyepiece
B) A millimeter-long ruler on a slide used to calibrate the eyepiece graticule ✅
C) A magnification lens
D) The focusing mechanism




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, 11. Why do we stain specimens?
A) To magnify them
B) To provide more contrast and make structures easier to distinguish ✅
C) To destroy unwanted cells
D) To fix them to the slide



12. What is differential staining?
A) Using multiple stains for decoration
B) Using a stain to distinguish between different organisms or organelles ✅
C) Staining only cell walls
D) Staining with fluorescent dyes only



13. What is the formula for magnification?
A) Image size × Actual size
B) Magnification = Image size ÷ Actual size ✅
C) Magnification = Actual size ÷ Image size
D) Magnification = Resolution × Image size



14. How is actual size calculated?
A) Image size × Magnification
B) Image size ÷ Magnification ✅
C) Magnification ÷ Image size
D) Resolution × Image size



15. How do we determine image size?
A) By multiplying magnification
B) By measuring with a ruler ✅
C) By using the stage micrometer only
D) By reading from the eyepiece



16. What does magnification refer to?
A) Clarity of image
B) The measure of how much larger the image appears compared to the specimen ✅
C) The distance between lenses
D) The strength of the microscope bulb



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