BIOL 221 L4

What type of microscope views a specimen with light reflected from the specimen rather than passed through the specimen?

• bright field

• phase contrast

• confocal scanning laser

• interference (Nomarski)

• dark field

What type of microscope would you use to examine a biofilm that was 2 mm thick?

• phase contrast

• interference (Nomarski)

• confocal scanning laser

• transmission electron

• atomic force

What type of microscope measures electric current passing through a probe rather than using any part of the electromagnetic spectrum?

• atomic force

• interference (Nomarski)

• scanning electron

• electron tomography

• bright field

What is the main difference between a negative stain and a positive stain?

• A negative stain has a negative charge; a positive stain is positively charged.

• A negative stain is used for Gram negative cells, a positive stain for Gram positive.

• A negative stain stains negative charges; a positive stain stains positive charges.

• A negative stain is not charged, and stains the background rather then the cell.

• A negative stain stains the inside of cells; a positive stain stains the outside.

Which type of microscope uses special prisms to make a thin specimen appear pseudo-3-dimensional?

• Phase Contrast

• Dark Field

• Scanning Electron Microscope

• Differential Interference Contrast

• Atomic Force Microscope

What is the main advantage of using an electron beam rather than light to illuminate a specimen?

• The electron beam is brighter

• The electron beam penetrates thick specimens better

• Electrons have a shorter wavelength than light

• It is easier to focus an electron beam

• An electron beam can be used to view live, unstained cells

Tags

NGSS.HS-PS4-3

What is the best technique to use if you wish to count the relative numbers of two different bacterial species on the same slide?

• Bright Field, with a negative stain

• Fluorescence Microscope, with fluorescent antibody stain

• Phase Contrast microscope, with a Gram stain

• Atomic Force Microscope, unstained

• Confocal Scanning Laser Microscope, with a simple stain

Which type of microscopy would be most suitable for examining the 3-dimensional appearance of magnetosomes inside a bacterial cell?

• Differential Interference Contrast

• Phase Contrast

• Transmission Electron Microscopy

• Confocal Scanning Laser Microscopy

• Cryo Electron Tomography

Why can't live bacteria be seen well with a bright field microscope?

• They are too small.

• The resolution of a bright field microscope is too poor.

• The high energy light of the bright field microscope kills them.

• Bright field microscopes "see" 3-dimensions, but bacteria have only two.

• The contrast achieved by bright field microscopy is too low.

Which of the following microscopes depends on interference of illuminating waves that pass through internal cellular structures that have a different refractive index?

• Transmission Electron Microscope

• Dark field Microscope

• Phase Contrast Microscope

• Cryo Electron Tomograph

• Fluorescence Microscope