1 The microscope in cell studies

What is the definition of the resolution of a light microscope?

• the degree of sharpness produced by the microscope

• the greatest distance between two objects visible in the same field of view

• the minimum distance that allows two objects to be viewed as separate

• the size of the smallest object visible using the microscope

Which row shows the correct order of size of these cell structures from the largest to the smallest?

1 width of a mitochondrion

2 width of a ribosomes

3 width of a cell surface membrane

4 width of a chloroplast

• 1 -> 4 -> 2 -> 3

• 1 -> 4 -> 3 -> 2

• 4 -> 1 -> 2 -> 3

• 4 -> 2 -> 1 -> 3

What is the typical resolution of a microscope using daylight as a light source with a x10 eyepiece lens and a x40 objective lens?

• 0.20 nm

• 200 nm

• 100 μm

• 400 μm

A student calibrated the scale on an eyepiece graticule in the eyepiece lens of a light microscope. The students was given a stage micrometer to use.

The divisions on the stage micrometer scale were 0.1 mm apart.

Which data must the student collect in order to calibrate the eyepiece graticule?

1 magnification of the eyepiece lens of the microscope

2 number of divisions of the stage micrometer scale sene in one field of view of the microscope

3 number of divisions of the eyepiece graticule scale equivalent to each division of the stage micrometer scale

• 1 and 3

• 2 and 3

• 2 only

• 3 only

A prokaryotic cell which is 1 μm in diameter is magnified 50 000 times in an electron micrograph.

What is the diameter of the cell in the electron micrograph?

• 5 × 10ˆ-1 mm

• 5 × 10ˆ0 mm

• 5 × 10ˆ1 mm

• 5 × 10ˆ2 mm

A discovered Pandoravirus measures 1000 nm in diameter.

The Mimivirus has a diameter of 400 nm.

What can be detected using a light microscope with a maximum resolution of 0.25 μm?

• Both Pandoravirus and Mimivirus

• Neither Pandoravirus nor Mimivirus

• The Mimivirus but not the Pandoravirus

• The Pandoravirus but not the Mimivirus

The diagram shows an eyepiece graticule and part of a stage micrometer scale as seen using x100 magnification.

How is the value, in μm, of one eyepiece graticule unit calculated?

• divide 100 by 0.1 and multiply by 1000

• divide 100 by 0.1 and multiply by 1000 divided by 100

• multiply 0.1 by 1000 and divide by 100

• multiply 0.1 by 1000 and divide 100 then divide again by 100

Which statement about light microscopes are correct?

1 To calculate the magnification of a light microscope the eyepiece lens and objective lens magnification are added together.

2 As the magnification increases the resolution decreases.

3 The resolution of a light microscope is limited by the wavelength of light.

4 The scale on a stage micrometer is resolved more clearly than an eyepiece graticule.

• 1, 2, 3 and 4

• 1, 3 and 4 only

• 2 and 3 only

• 2 and 4 only

Different units are used when measuring biological specimens.

Which measurements in mm has not been correctly converted into both μm and nm?

• A

• B

• C

• D

A student has drawn a cell structure as seen using a light microscope.

The magnification of the drawing is ×600.

The length of the structure on the drawing is 6 mm.

What is the actual length of the cell structure/

• 1 × 10ˆ-1 μm

• 1 × 10ˆ0 μm

• 1 × 10ˆ1 μm

• 1 × 10ˆ2 μm