A LEVEL BIOLOGY OCR QUESTIONS AND CORRECT ANSWERS RATED A+

A LEVEL BIOLOGY OCR QUESTIONS AND
CORRECT ANSWERS RATED A+
QUESTION
What is a light microscope used for?

CORRECT ANSWER
Observing living and dead specimens.



QUESTION
What are the pros and cons of a light microscope?

CORRECT ANSWER
Pros: Cheap, portable, easy to use, can study living specimens.
Cons: Limited magnification and poor resolution.



QUESTION
What is a laser scanning confocal microscope used for?

CORRECT ANSWER
Creating high-resolution, high-contrast images at different depths of a specimen.



QUESTION
What is a transmission electron microscope (TEM) used for?

CORRECT ANSWER
Observing the internal ultrastructure of cells under very high magnification and resolution.



QUESTION
What is a scanning electron microscope (SEM) used for?

CORRECT ANSWER
Viewing the surface of objects under high magnification and resolution.

, QUESTION
What are the pros and cons of electron microscopes?

CORRECT ANSWER
Pros: Very high magnification and excellent resolution.
Cons: Specimens must be dead, very expensive, very large, require skilled operators.



QUESTION
What is the difference between a TEM and an SEM?

CORRECT ANSWER
TEM transmits electrons through the specimen; SEM reflects electrons off the specimen surface.



QUESTION
What is the difference between light and electron microscopes?

CORRECT ANSWER
Light microscopes use light and glass lenses; electron microscopes use electrons focused by
magnets.



QUESTION
What is an eyepiece graticule?

CORRECT ANSWER
A small ruler fitted into a microscope eyepiece that must be calibrated before use.



QUESTION
What is a stage micrometer?

CORRECT ANSWER
A slide with a 1 mm scale divided into 100 parts (each 10 µm) used to calibrate the eyepiece
graticule.