Exam 3: Observing Microorganisms Through a Microscope

Both phase-contrast microscopy and differential interference contrast microscopy are used to view the internal structures of cells without staining.

Which demonstrates better resolution?

Assume you stain Bacillus by applying malachite green with heat and then counterstaining with safranin.Through the microscope,the green structures are

You are performing a Gram stain on gram-negative bacteria and you stop after the decolorizer step.What is the appearance of the bacteria at this point?

Which microscope is used to see intracellular detail in a living cell?

Cells viewed in darkfield microscopy appear similar to those stained with the negative stain.

The limit of resolution of the compound microscope illuminated with visible light is approximately 0.2 μm.

Which of the following correctly traces the path of light through the compound microscope?

Which of the following pairs is mismatched?

Which of the following is NOT true regarding the acid-fast stain?

You are performing a Gram stain on gram-positive bacteria and you stop after the addition of the counterstain.What is the appearance of the bacteria at this point?

Which microscope can be used to visualize DNA or botulinum toxin?

Which microscope uses two beams of light to produce a three-dimensional color image?

Which microscope achieves the highest magnification and greatest resolution?

Which two staining techniques employ a mordant?

Which microscope is used to see internal structures of cells in a natural state?

Which microscope is best used for observing the surfaces of intact cells and viruses?

A student is looking at a bacterial specimen using the oil immersion lens,but has forgotten to put immersion oil on the slide.The specimen will appear

In 1877,Robert Koch thought preparing permanently stained slides would be valuable.Why was his assessment correct?

If a patient had a bacterial infection that was not syphilis but was tested for syphilis using the FTA-ABS test,what would the technician observe?