Microscope in cell study

Which feature is visible with a light microscope using a natural light source?

• DNA molecule of diameter 2 nm

• Paramecium cell of diameter 200 nm

• phospholipid bilayer of 8 nm

• ribosome of diameter 20 nm

A specimen is observed twice with a microscope, firstly using green light with a wavelength of 510nm and then with a wavelength of red light with a wavelength of 650nm.

What happens to the magnification and resolution when using red light compared to green light?

• magnification decreases, resolution remains the same

• both the magnification and resolution increases

• magnification remains the same, resolution decreases

• magnification remains the same, resolution increases

A student calibrated an eyepiece graticule using a stage micrometer.

Each division of the stage micrometer was 0.01 mm.

With a X10 magnification objective lens, 10 eyepiece graticule units matched 10 divisions on the stage micrometer.

The same microscope was used with a X40, instead of a X10, magnification objective lens to measure the diameter of an alveolus. The diameter of the alveolus was found to be 96 eyepiece graticule units. The eyepiece lens was not changed.

What is the best estimate for the diameter of the alveolus?

• 0.960 mm

• 3.84 mm

The diagram shows an eyepiece graticule and a cell viewed through a microscope. When the eyepiece graticule was calibrated at this magnification, the whole length of the graticule shown covered 12 divisions of a stage micrometer scale. There were 100 divisions in 10 mm of the stage micrometer.

What is the actual length of the cell?

• 2.5 µm

• 3.6 µm

• 360 µm

• 3 mm

Until recently, the typical viruses known to science were 20–150 nm in size.

In 2003, the Mimivirus was discovered with a size of approximately 680 nm.

In 2013, the Pandoravirus was discovered which has a size of over 1000 nm.

Which viruses can be seen using a light microscope with a maximum resolution of 0.25 µm and an electron microscope?

• A

• B

• C

• D

The mean width of mitochondria in an electron micrograph is 6 mm. The magnification of the electron micrograph is X9600. What is the actual mean width of the mitochondria?

• 2

• 17

• 60

• 167

• divide 100 by 0.1 then multiply by 1000

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

• multiply 0.1 by 1000 then divide by 100

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

• 0.5 mm

• 5 mm

• 50 mm

• 500 mm

A student observes a cell using a light microscope. The student then draws the cell.

Which items will the student need to calculate the magnification of the drawing?

1 eyepiece graticule

2 ruler

3 hand lens

4 stage micrometer scale

• 1, 2, 3 and 4

• 1, 2 and 4 only

• 1 and 3 only

• 2 and 4 only