Micro Chapter 3 Mastering Questions

electron microscope

In using this microscope, the observer does NOT look directly at an image through a lens. fluorescence microscope electron microscope phase-contrast microscope darkfield microscope compound light microscope

E. make the flagella visible.

The purpose of a mordant in the Gram stain is to A. make gram-negative cells visible. B. remove the simple stain. C. make the bacterial cells larger. D. prevent the crystal violet from leaving the cells. E. make the flagella visible.

used to focus the light from the illuminator onto the slide

What does the condenser do?

lens that is closest to the slide and provides initial magnification of a specimen

What does the objective lens do?

scanning acoustic microscope

Which microscope is most useful for visualizing a biofilm? phase-contrast microscope fluorescence microscope transmission electron microscope scanning acoustic microscope compound light microscope

projector lens

Which of the following is a lens found on electron microscopes but not on light microscopes? Objective lens Projector lens Eyepiece lens Condenser lens

gram stain

Which type of stain is most useful in helping clinicians to decide which antibiotic to prescribe for a bacterial infection? simple stain negative stain flagella stain Gram stain endospore stain

transmission electron microscope

Which viewing method is most appropriate for viewing ribosomes (20 nm) within a bacterial cell? unaided eye light microscope scanning electron microscope transmission electron microscope

false

true or false: In a completed Gram stain, gram-negative bacteria are colorless.

true

true or false: Nigrosin staining-not safranin staining-of Klebsiella pneumoniae will allow for the visualization of the cell shape and the determination of the presence of a capsule.

0.15 mm

A paramecium is approximately 150 micrometers in length. What is this measurement expressed in millimeters (mm)?

0.1 μm

A virus measures 100 nm in length. What is its length in μm?

Mycobacterium

Acid-fast staining is used to detect members of which bacterial genus? Mycobacterium Staphylococcus Streptococcus Clostridium

D. Rinsing with alcohol during the washing step stripped the bacteria off the glass slide.

After examining the slide under oil immersion, you determine that no bacteria are present even though the student is able to show you the culture he used to make that slide that has visible growth in the liquid medium. Which of the following statements does NOT explain the fact that there are no bacteria present on the student's slide? A. Overheating during the fixation step boiled the water within the bacterial cells and resulted in the cells bursting. B. Insufficient heating of the slide did not drive out the thin layer of water and this resulted in minimal bonding between the bacteria and the glass slide. C. By not allowing a glass slide to completely air dry before heat fixation, the flame will cause the surrounding water to boil and this will damage the bacterial cell. D. Rinsing with alcohol during the washing step stripped the bacteria off the glass slide.

C, A, D, E, B

Arrange these from smallest to largest A. Mastadenovirus (30nm) B. Clonorchis sinensis (5mm) C. Bacterial Plasmids (20nm) D. Gram positive bacteria (6 μm) E. Giardia lamblia (7 μm)

endospores

Assume you stain Bacillus by applying malachite green with heat and then counterstaining with safranin. Through the microscope, the green structures are flagella. cell walls. capsules. endospores. The answer cannot be determined.

affix the cells to the slide

Bacterial smears are fixed before staining to affix the cells to the slide. accept stain. make the cells visible. make their walls permeable.

250 nm

Chlamydia trachomatis elementary bodies measure approximately 0.25 micrometers in diameter. What is this measurement expressed in nanometers (nm)?

the objective lens

In a typical brightfield microscope (seen in the animation), at which point does magnification begin? The lamp The stage The condenser lens The objective lens The ocular lens

C, A, D, B

Put the following descriptions in order for the staining reactions in the cells of a bacterial smear during the Gram staining procedure. A. Dye molecules are rendered insoluble in presence of mordant; dye is rinsed away. B. Clear cells are stained a red or pink whereas the color of other cells remains unchanged C. All cells are stained purple. D. Cell wall of Gram-negative cells is broken down; Gram-positive cells remain intact.

B. The positively charged methylene blue will be attracted to the negatively charged components of the cell wall and will be retained.

The single criterion for the project is to be able to determine cell shape and size in a pure broth culture after some treatments. No differentiation between cell types is required, you want to convince the student that a simple stain would be his best option. Which staining procedure would be best to use to stain the slides required for this student's project? Why? A. Using crystal violet followed by a rinse and Gram's iodine will stain the cells a dark blue with large crystals. B. The positively charged methylene blue will be attracted to the negatively charged components of the cell wall and will be retained. C. Malachite green and heat will colorize the cell for easier visualization and is a simple process. D. An acidic stain such as nigrosin will stain the cells a dark black coloration for easier viewing under the microscope.

used for initial focusing; should never be used when the high-power objective lens or oil immersion lens is in place

What does the coarse focus knob do?

controls how much light from the illuminator reaches the specimen

What does the diaphragm do?

used after initial focusing to sharpen the image

What does the fine focus knob do?

lens that you look through

What does the ocular lens do?

platform on which the slide is placed for viewing

What does the stage do?

D. They are reflected, refracted, or absorbed by the specimen.

What happens to the light rays when they hit the specimen? A. They are diverted to the ocular lens. B. They are absorbed by the stage. C. They are focused into a small area towards the objective lens. D. They are reflected, refracted, or absorbed by the specimen.

it is spreading out

What is meant by light rays being divergent? It is heading upwards It is coming together to a focused beam It is spreading out

D. They may be absorbed, reflected, or refracted by the specimen.

What is the fate of the electrons that interact with a specimen in an electron microscope? A. They are reflected by the specimen. B. They are refracted by the specimen. C. They are absorbed by the specimen. D. They may be absorbed, reflected, or refracted by the specimen.

C. Lenses focus either light or electrons to create a magnified image of a specimen.

What is the role of lenses in microscopy? A. Lenses increase the contrast to determine structural differences in stained specimens. B. Lenses are only used to magnify specimens that are smaller than whole red blood cells. C. Lenses focus either light or electrons to create a magnified image of a specimen.

to recreate the image in the viewer's eye

What is the role of the ocular lens?

C. observing two adjacent bacteria as individually having a width of 0.3μm

Which demonstrates better resolution? A. observing a clump of algae 0.5mm by 0.75 mm B. measuring two yeast cells as individually having a diameter of 10μm C. observing two adjacent bacteria as individually having a width of 0.3μm D. measuring a flea as 1.2mm at the longest point E. measuring two bacteria arranged end to end as individually having a length of 2μm

electron microscope

Which microscope achieves the highest magnification and greatest resolution? darkfield microscope compound light microscope fluorescence microscope electron microscope phase-contrast microscope

scanning electron microscope

Which microscope is best used for observing the surfaces of intact cells and viruses? fluorescence microscope scanning electron microscope darkfield microscope phase-contrast microscope brightfield microscope

two-photon microscope

Which microscope is used to see intracellular detail in a living cell? atomic force microscope two-photon microscope transmission electron microscope fluorescence microscope brightfield microscope

E. differential interference contrast microscope

Which microscope uses visible light? A. scanning electron microscope B. confocal microscope C. scanning acoustic microscope D. fluorescence microscope E. differential interference contrast microscope

E. If cells are acid-fast, they are gram-negative.

Which of the following is NOT true regarding the acid-fast stain? A. Acid-fast cells appear red in a completed acid-fast stain. B. It is used to identify members of the genus Mycobacterium. C. Acid-fast cells retain the primary dye after treatment with acid-alcohol. D. Non-acid-fast microbes appear blue in a completed acid-fast stain. E. If cells are acid-fast, they are gram-negative.

C. They both employ the use of objective lenses

Which of the following is a characteristic shared by both electron and light microscopes? A. Both microscopes have a resolving power of 0.01 nm. B. Both microscopes require an internal camera to visualize the specimen. C. They both employ the use of objective lenses. D. They both utilize white light to magnify the specimen.

B. fluorescence microscope - uses a fluorescent light

Which of the following pairs is mismatched? A. darkfield microscope - uses visible light B. fluorescence microscope - uses a fluorescent light C. scanning tunneling microscope - allows visualization of atoms D. scanning electron microscope - produces a three-dimensional image E. confocal microscope - produces a three-dimensional image

Acid-alcohol—decolorizing agent

Which of the following pairs of terms is properly matched? Steam heat—decolorizing agent Acid-alcohol—decolorizing agent Carbolfuchsin—decolorizing agent Methylene blue—decolorizing agent

2,4,1,3

Which of the following places the steps of the Gram stain in the correct order? 1-Alcohol-acetone 2-Crystal violet 3-Safranin 4-Iodine

weight gain

Which of the following signs and symptoms is NOT associated with active pulmonary tuberculosis? chest pain cough with blood weight gain fever

B. acid-fast stain for microbes with waxy cell walls

Which of the following staining procedures is matched with the principal use for that stain? A. negative stain used to differentiate cell wall components B. acid-fast stain for microbes with waxy cell walls C. endospore stain to visualize structures which enable bacteria to move and swim D. flagella stain used to distinguish dormant structures formed during adverse environmental conditions

gram stain; flagella stain

Which two staining techniques employ a mordant? Capsule stain; Flagella stain. Gram stain; Capsule stain. Simple stain; Acid-fast stain. Gram stain; Flagella stain. Gram stain; Acid-fast stain.

B. a transmission electron microscope

Which type of microscope would allow the viewer to see ribosomes inside a cell? A. A light microscope, transmission electron microscope, and scanning electron microscope can all view ribosomes inside a cell. B. A transmission electron microscope C. A scanning electron microscope D. A light microscope

light microscope

Which viewing method is most appropriate for examining a clinical specimen, such as a sputum smear, for the presence of bacteria? unaided eye light microscope scanning electron microscope transmission electron microscope

scanning electron microscope

Which viewing method is most appropriate for viewing the three-dimensional shape of a protozoan and the arrangement and distribution of cilia on its surface? unaided eye light microscope scanning electron microscope transmission electron microscope

transmission electron microscope

Which viewing method is most appropriate for confirming the 9 + 2 microtubule arrangement in a eukaryotic flagellum? unaided eye light microscope scanning electron microscope transmission electron microscope

scanning electron microscope

Which viewing method is most appropriate for determining the three-dimensional shape and arrangement of bacterial cells? unaided eye light microscope scanning electron microscope transmission electron microscope

light microscope

Which viewing method is most appropriate for examining a blood smear for the presence of malarial parasites? unaided eye light microscope scanning electron microscope transmission electron microscope

unaided eye

Which viewing method is most appropriate for examining your cat for the presence of fleas? unaided eye light microscope scanning electron microscope transmission electron microscope

transmission electron microscope

Which viewing method is most appropriate for viewing a cross section of poliovirus (30 nm)? unaided eye light microscope scanning electron microscope transmission electron microscope

transmission electron microscope

Which viewing method is most appropriate for viewing the layers of the gram-negative cell wall in cross section? unaided eye light microscope scanning electron microscope transmission electron microscope

mycolic acid

Which waxy molecule, found in the cell wall of acid-fast bacteria, prevents these cells from being Gram stained? acid-alcohol mycolic acid methylene blue carbolfuchsin

D. Electrons have a smaller wavelength than visible light, leading to higher resolution.

Why do electron microscopes have higher resolving power than light microscopes? A. They are capable of producing 3-dimensional images, which light microscopes cannot do. B. The copper grid used in electron microscopy provides enhanced resolution. C. The fluorescent screen adds another magnification step. D. Electrons have a smaller wavelength than visible light, leading to higher resolution.

A. Anything smaller than 200 nm cannot interact with visible light.

Why is a specimen smaller than 200 nm not visible with a light microscope? A. Anything smaller than 200 nm cannot interact with visible light. B. It is too easy to lose on the stage. C. Visible light is only good at wavelengths below 390 nm. D. The lenses only go to 100 X magnification power.

colorless

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? purple red colorless brown

scanning electron microscope

You are studying a cell structure that is approximately 100 nm in size. Which of the following provides the greatest magnification you can use to see the cellular structure in three-dimensions? phase-contrast microscope scanning electron microscope transmission electron microscope brightfield microscope darkfield microscope