Micro Week 2 Quiz

Which of the following is NOT equal to 1 mm? ANSWER: 100 μm 1,000,000 nm 0.1 cm 0.001 m 1,000.000.000 pm

A virus measures 100 nm in length. What is its length in μm? ANSWER: 0.01 μm 10 μm 0.001 μm 1 μm 0.1 μm

A microorganism measures 5 μm in length. Its length in mm would be ANSWER: 500 mm. 0.05 mm. 0.005 mm. 0.5 mm. 50 mm.

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

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

What is the role of the ocular lens? ANSWER: To focus the light to a high intensity in a small area To recreate the image in the viewer's eye To do the bulk of the magnification To adjust the wavelength of light

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

In a typical brightfield microscope, at which point does magnification begin? ANSWER: The ocular lens The stage The condenser lens The objective lens The lamp

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

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

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

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

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

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

What structure does light pass through after leaving the condenser in a compound light microscope? ANSWER: specimen ocular lens objective lens illuminator

Which microscope uses visible light? ANSWER: confocal microscope fluorescence microscope scanning electron microscope scanning acoustic microscope differential interference contrast microscope

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

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

This microscope produces an image of a light cell against a dark background; internal structures are NOT visible. ANSWER: electron microscope compound light microscope darkfield microscope fluorescence microscope phase-contrast microscop

Which of the following is never useful for observing living cells? ANSWER: scanning acoustic microscope scanning electron microscope darkfield microscope phase-contrast microscope brightfield microscope

Which of the following correctly traces the path of light through the compound microscope? ANSWER: light source; specimen; condenser; objective lens; ocular lens condenser; light source; specimen; objective lens; ocular lens light source; condenser; specimen; objective lens; ocular lens light source; condenser; objective lens; specimen; ocular lens condenser; light source; specimen; ocular lens; objective lens

In the figure, line "c" points to the microscope's ANSWER: ocular lens. objective lens. illuminator. condenser.

Which microscope can be used to visualize DNA or botulinum toxin? ANSWER: scanning tunneling microscope scanning electron microscope confocal microscope phase-contrast microscope compound light microscope

Which microscope is used to observe a specimen that emits light when illuminated with an ultraviolet light? ANSWER: electron microscope compound light microscope fluorescence microscope darkfield microscope phase-contrast microscope

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

Which microscope takes advantage of differences in the refractive indexes of cell structures? ANSWER: compound light microscope darkfield microscope phase-contrast microscope fluorescence microscope electron microscope

Which of the following pairs is mismatched? ANSWER: scanning tunneling microscope - allows visualization of atoms darkfield microscope - uses visible light fluorescence microscope - uses a fluorescent light confocal microscope - produces a three-dimensional image scanning electron microscope - produces a three-dimensional ima

What is the total magnification of a specimen viewed with a 10x ocular lens and a 45x objective lens? ANSWER: 100x 45x 10x 4.5x 450x

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 this structure? ANSWER: brightfield microscope phase-contrast microscope transmission electron microscope darkfield microscope scanning electron microscope

Which microscope uses two beams of light to produce a three-dimensional color image? ANSWER: phase-contrast microscope DIC microscope darkfield microscope electron microscope fluorescence microscope

Which microscope is used to observe viruses and the internal structure of thinly sectioned cells? ANSWER: darkfield microscope brightfield microscope transmission electron microscope scanning electron microscope fluorescence microscope

Which microscope is used to see detail of a 300-nm virus? ANSWER: DIC microscope darkfield microscope fluorescence microscope phase-contrast microscope electron microscope

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

The resolution of a microscope can be improved by changing the ANSWER: fine adjustment. condenser. wavelength of light. diaphragm. coarse adjustment.

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 ANSWER: somewhat fuzzy and have poor resolution. the same as it would if the immersion oil was used. larger than it would if immersion oil was used. smaller than it would if immersion oil was used. to have no color.

The purpose of the ocular lens is to ANSWER: improve resolution. decrease the refractive index. increase the light. decrease the light. magnify the image from the objective lens.

If acid-fast bacteria are stained with the Gram stain, they will stain gram-negative. ANSWER: True False

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

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

The greater resolution of the electron microscope compared to the compound microscope is due to the longer wavelengths of the electrons used to examine specimens. ANSWER: True False

Scanned probe microscopy is used to examine fine detail of molecular complexes, such as blood clots, or molecules, such as DNA. ANSWER: True False

Which of the following pairs is mismatched? ANSWER: acidic dye - capsule stain crystal violet - simple stain methylene blue - simple stain nigrosin - negative stain basic dye - negative stain

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 ANSWER: 1-2-3-4 1-3-2-4 2-4-1-3 4-3-2-1 2-1-4-3

Which of the following pairs is mismatched? ANSWER: safranin - acid dye iodine - mordant carbolfuchsin - basic dye crystal violet - basic dye alcohol-acetone - decolorizer

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

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

Which of the following places the steps in the correct sequence? 1-Staining 2-Making a smear 3-Fixing ANSWER: 2-3-1 1-3-2 1-2-3 3-2-1 The order is unimportant.

The negative stain is used to ANSWER: determine Gram reaction. determine flagella arrangement. visualize fimbriae. determine cell size. visualize endospores.

Simple staining is often necessary to improve contrast in which microscope? ANSWER: electron microscope phase-contrast microscope fluorescence microscope compound light microscope darkfield microscope

You are performing a Gram stain on gram-positive bacteria and you stop after the addition of the first dye. What is the appearance of the bacteria at this point? ANSWER: purple red colorless brown

You are performing a Gram stain on gram-negative bacteria and you stop after the addition of the mordant. What is the appearance of the bacteria at this point? ANSWER: purple red colorless brown

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? ANSWER: purple red colorless brown

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? ANSWER: purple red colorless brown

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

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

You find colorless areas in cells in a Gram-stained smear. What should you do next? ANSWER: an endospore stain an acid-fast stain a simple stain a flagella stain a capsule stain

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

In microscopy, the term resolution ANSWER: refers to magnification when using the electron microscope. refers to the ability to distinguish fine structure and detail in a specimen. is the same as the total magnification of a specimen. is only observed in stained specimens. is improved when longer wavelengths of light are employed.

The counterstain used in the Gram stain is a basic dye. ANSWER: True False

In a completed Gram stain, gram-negative bacteria are colorless. ANSWER: True False

In a completed Gram stain, gram-positive bacteria are purple. ANSWER: True False

Cells viewed in darkfield microscopy appear similar to those stained with the negative stain. ANSWER: True False

The capsules and flagella of bacteria can be observed in gram-stained smears. ANSWER: True False

Which of the following staining procedures is matched with the principal use for that stain? Hint 1. The components and structures of the microbe being examined are important for determining the type of staining procedure to use. ANSWER: endospore stain to visualize structures which enable bacteria to move and swim acid-fast stain for microbes with waxy cell walls flagella stain used to distinguish dormant structures formed during adverse environmental conditions negative stain used to differentiate cell wall components

Which of the following types of microscopy provides advantages for viewing live images? Hint 1. Preparation of microbes for microscopy depends on the type of microscope and process necessary to visualize the cells or components of the cells. ANSWER: darkfield microscopy scanning electron microscopy transmission electron microscopy fluorescent microscopy

When an object is viewed through a light microscope with oculars that magnify 20 20× and a high-power objective lens that magnifies 100 ×, what is the total magnification of the object? Hint 1. Review "Microscopy: The Instruments" in Chapter 3. ANSWER: 200× 800 × 1000× 2000 ×

Which of the following statements comparing electron microscopy and light microscopy is FALSE? Hint 1. Consider the source of illumination for these two microscopes and the resulting virtual image. ANSWER: -mages produced by light microscopes can be in color, whereas electron microscope images are black and white unless they are artificially colored. -Electron microscopes can allow examination of viruses and internal cell structures, whereas light microscopes are limited to objects that are 0.5 micrometers and larger. -Both the electron microscope and the light microscope use the same wavelengths for illumination. -The electron microscope has greater resolution than the light microscope.

What is the role of iodine in the Gram stain process? Hint 1. Make a list of the Gram stain reagents and the order they are applied, and then consider the action of each reagent in the process. ANSWER: -Iodine is a mordant in the Gram stain technique, which functions to intensify the primary stain. -Iodine is the decolorizer removing the primary stain after the first step in the Gram stain technique. -Iodine is a basic purple dye, which acts as the primary stain in the Gram stain technique. -Iodine is a pink dye that acts as the primary stain in the Gram stain technique.

Which of the following describes the correct path of light in a compound light microscope, from the illumination source to the eye of the observer? Hint 1. Using a diagram of a microscope, track the pathway of light from the light source to the eye, and consider the function of each structure. ANSWER: -objective lenses → specimen → illuminator → condenser lenses → body tube → ocular lens → eye -condenser lenses → illuminator → specimen → objective lenses → body tube → ocular lens → eye -illuminator → condenser lenses → specimen → objective lenses → body tube → ocular lens → eye -Illuminator → ocular lens → body tube → condenser lenses → specimen → objective lenses → eye

What does resolution mean? Hint 1. Consider what is meant by the resolving power of a lens. ANSWER: -a measure of the ability of a medium to bend light -the ability of a microscope to distinguish fine details and differentiate between two very close objects -the total magnification of the visual image seen -the ability of a microscope to stay in focus when the objective lenses are moved from low power to high

Which of the following measurements is correctly matched with microorganisms of that size? Hint 1. Rather than memorizing exact measurements, think about the relative size of each of these microbes in relation to each other. ANSWER: Yeast; 1 centimeter Bacteria; 10 nanometers Viruses; 10 micrometers Bacteria; 2 micrometers

Which of the following statements about gram-negative cell walls is FALSE? ANSWER: Their Gram reaction is due to the outer membrane. They are sensitive to penicillin. They are toxic to humans. They protect the cell in a hypotonic environment. They have an extra outer layer composed of lipoproteins, lipopolysaccharides, and phospholipids.

In the figure, which diagram of a cell wall is decolorized by a brief exposure to alcohol? ANSWER: a b both a and b neither a nor b The answer cannot be determined based on the information provided.

In the figure, which diagram of a cell wall is resistant to many antibiotics (e.g., penicillin)? ANSWER: a b both a and b neither a nor b The answer cannot be determined based on the information provided.