A-Level Biology –
OCR 100%
VERIFIED
ANSWERS
Describe what is meant by residual volume and state
the standard volume - CORRECT ANSWER-The
volume of air that remains in the lungs even after
forced expiration, i.e. the air that remains in the
airways and alveoli (usually 1.5 dm3)
Describe w...
,Describe what is meant by residual volume and state
the standard volume - CORRECT ANSWER-The
volume of air that remains in the lungs even after
forced expiration, i.e. the air that remains in the
airways and alveoli (usually 1.5 dm3)
Describe what is meant by tidal volume stating a
typical figure - CORRECT ANSWER-Volume of air
moved in and out with each breath at rest. A normal
value would be 0.5 dm3.
What is a light microscope used for? - CORRECT
ANSWER-Observing living and dead specimins
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, poor resolution.
,What is a laser scanning confocal microscope used
for? - CORRECT ANSWER-Creating a high
resolution, high contrast image, at different depths of
the specimen.
What is a transmission electron microscope be used
for? - CORRECT ANSWER-Observing the internal
ultrastructure of cells under high magnification and
resolution
What is a scanning electron microscope used for? -
CORRECT ANSWER-Viewing the surface of objets
under high magnification and resolution
What are the pros and cons of an electron
microscope? - CORRECT ANSWER-Pros: Very high
magnification and excellent resolution. Cons:
specimen has to be dead, very expensive, very large,
needs great skill and training to use.
, What is the difference between a transmission and
an scanning electron microscope? - CORRECT
ANSWER-TEM sends a beam of electrons through
the specimen, the SEM bounces electrons off the
surface.
What is the difference between light and electron
microscopes? - CORRECT ANSWER-Light uses
lenses to focus a beam of light. Electron uses a beam
of electrons, focused by magnets.
What is an eye piece graticule? - CORRECT
ANSWER-A small ruler fitted to a light microscope's
eyepiece. It must be calibrated using a stage
micrometer before being used to measure
specimens.
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