Microbiology test 2

Who invented the first crude microscope by grinding glass?

Leeuwenhoek

The simple microscopes used by the earliest practitioners of microscopy contained which of the following?

Magnifying lens

The ___ of the microscope holds and allows selection of the objective lenses.

nosepiece

Which of the following parts of a microscope magnifies the specimen to produce a real image of the specimen?

Objective lens

Which of the following parts of the microscope magnifies the specimen to produce the virtual image of the specimen?

Ocular lens

If a microbiologist is studying a specimen at a total magnification of 950X, what is the magnifying power of the objective lens if the ocular lens is 10X?

95X

Magnification is achieved in a compound microscope through the initial magnification of the specimen by the __________ lens. This image is then projected to the __________ lens that will further magnify the specimen to form a virtual image received by the eye.

objective; ocular

Which term refers to the microscope's ability to show two separate objects as discrete and distinct?

Resolution

The wavelength of light used and the numerical aperture governs

Resolution

Scattering of peripheral light rays through the glass slide under very high magnification can be prevented by

immersion oil.

The type of microscopy in which you would observe brightly illuminated specimens against a black background is

dark-field.

Which type of microscope shows cells against a white background?

Bright-field

True or false: The bending of light rays as they pass from one medium to another is called refraction.

True

Which type of microscope does not use light in forming the specimen image?

Electron

Which type of microscope achieves the greatest resolution and highest magnification?

Electron

Which type of microscope cannot image live specimens?

Electron

True or false: Fixed smears of specimens are required to perform the Gram stain or the endospore stain.

True

True or false: When observing specimens with the 100x lens, adding a drop of oil to the slide will improve the resolving power; the image will be clear rather than blurry.

True 

True or false: Light rays with shorter wavelengths enhance the ability to resolve objects that are close together.

True

True or false: The degree of contrast between a specimen and its surroundings is enhanced by the use of special stains and opening the iris diaphragm wide to allow in maximum light.

False

True or false: If the 40x high-powered lens is used to view a specimen in conjunction with a 10X ocular, the total magnification of the specimen will be 50x.

False

True or false: If oil is not used with the 100x lens, the virtual image will be less bright, compared to specimens observed with a drop of oil on the slide.

False

Which of these types of organisms is least likely to be identified to the genus level with light microscopy? 

Bacteria

Cells of Staphylococcus aureus are cocci measuring about 1 μm in diameter. In a textbook image of S. aureus, each cell measures about 1 cm. The magnification of the image on the page is

10,000x

Your microscope has a resolving power of 0.15 μm. The specimen that you will be observing has bacterial cocci the size of 0.1 μm in diameter. Which of the following statements is correct?

The cocci will be fuzzy-looking and blend together.

The simple microscopes used by the earliest practitioners of microscopy contained which of the following?

Magnifying lens

Which of the following parts of a microscope magnifies the specimen to produce a real image of the specimen?

Objective lens

Which of the following parts of the microscope magnifies the specimen to produce the virtual image of the specimen?

Ocular lens

True or false: The bending of light rays as they pass from one medium to another is called refraction.

True

Which type of microscope achieves the greatest resolution and highest magnification?

Electron

The specimen preparation technique that is best for viewing cell motility is the

hanging drop

Basic dyes are

attracted to the acidic surface of bacterial cells.

True or false: Bacterial cultures are easily identified from their microscopic appearance.

False

The specimen preparation technique that is best for viewing cell motility is the

hanging drop

The purpose of staining cells on a microscope slide is to

add contrast to see them better.

The Gram staining procedure is best described as a __________ staining technique.

differential

What do the Gram stain, the acid-fast stain, and the endospore stain have in common?

They are differential stains.

A microbiologist makes a fixed smear of bacterial cells and stains it with methylene blue. All cells appear blue under the oil immersion lens. This is an example of

simple staining.

True or false: Fixed smears of specimens are required to perform the Gram stain or the endospore stain.

True

True or false: Following a properly-performed Gram stain, gram-positive bacteria will appear as pink or red cells.

False

The specimen preparation technique that is best for viewing cell motility is the

hanging drop.

The purpose of staining cells on a microscope slide is to

add contrast to see them better.

The Gram staining procedure is best described as a __________ staining technique.

differential

A microbiologist makes a fixed smear of bacterial cells and stains it with methylene blue. All cells appear blue under the oil immersion lens. This is an example of

simple staining.

True or false: Fixed smears of specimens are required to perform the Gram stain or the endospore stain.

True

True or false: Following a properly-performed Gram stain, gram-positive bacteria will appear as pink or red cells.

False

What differential stain is most important in the diagnosis of tuberculosis?

Acid-fast stain

A human squamous cell measures 75 micrometers (µm) in diameter. What is the size of this cell in millimeters (mm)?

0.075 mm

What was the largest organism you observed in the lab under compound microscope?

Helminth

What was the smallest organism you observed?

Bacteria

Why is it desirable that microscope objectives be parfocal?

Parfocality reduces the amount of time needed to locate and observe the specimen

Which objective lens is placed closest to the slide when it is in focus? Hint: has the smallest working distance

Oil immersion objective lens

What would occur if water were accidentally used in place of oil while using the oil immersion lens?

If water were accidentally used instead of immersion oil, additional light would be lost and the image would not appear as clear

Calculate the total magnification of scanning power objective?

40x

Calculate the total magnification of low power objective?

100x

Calculate the total magnification of high dry power objective?

400x

Calculate the total magnification of oil immersion power objective?

1000x

Which of the following would be the easiest to resolve with the 4x objective lens?

Two amoeba that are 5um apart

The ______ is the ability to distinguish between two points that are very close together to one another.

Resolving power

The ______ is the ability to enlarge an objective relative to its actual size.

Magnifying power

Cell wall components: no cell wall

protozoa

Cell wall components: peptidoglycan

bacteria

Cell wall components: chitin

fungi

Cell wall components: starch/cellulose

algae

When you add immersion oil while observing under 100x objective lens, the light behavior follows what pattern?

the refraction of light decreases and the light scatter decreases

True or false: You use a “binocular” microscope in the classroom

False

As you wrap up the microscope at the end of the lab activity you will.

switch off the light bulb, clean the lenses of the microscope with lens paper, lower the microscope stage to the lowest position, rotate objectives so that scanning objective is in focus position

Size of the smallest object that a human eye can view with ease, ranges in?

mili-meter

With fungi, ___ serve as opportunistic pathogens while ____ serves as true pathogens

yeasts;mold

Non pathogenic microbes?

archaea and algae

Hooks and suckers that help with causing infection are present in?

helminth

Cilia, pseudopods, and flagella, as motility organs, can be found in what category of microbes?

protozoa

Who is the photosynthetic microbe?

algae

Algae does ____

photosynthesis

Helminths ___

host gastric juice

Fungi are ____

decomposers 

Choose the wrong pair of disease and microbe.

cyanobacteria & mycoses

All species of bacteria have?

cell membrane, ribosomes, DNA

Some species of Bacteria?

endospores, pili, capsule, flagella

Coccus is _____ shaped

spherical cell

Bacillus is ____ shaped

cylindrical or rod-shaped cell

Spirillum and spirochete is ____ shaped

spiral or helical-shaped cell

Diplococcus has ___

2 Spherical shape

Tetrad has ___

4 Spherical shape

Sarcina has ____

8 Spherical shape

Streptococcus has ____

6 Spherical shape in a line

Staphylococcus has ____

more than 8 spherical shape

Nanotubes are extensions of the _________ that can function in _________.

membrane; nutrient transfer 

Bacterial endospores usually function in

survival

What type of macromolecule makes up the bacterial capsule?

Carbohydrates

What does the capsule typically look like on a stained smear when viewing under the light microscope?

Clear halos around the cells

A culture of Klebsiella colonies is smooth, indicating the presence of a capsule. A culture of Pseudomonas shows rough colonies. Based on this information alone, which species is likely to be more pathogenic?

Klebsiella

Why is the capsule considered a virulence factor?

The presence of the capsule allows a bacterium to evade the immune system and cause damage to the host.

Which of these pairs is incorrectly matched?

Fimbriae–motility

Select all of the characteristics of fimbriae.

Participate in biofilm formation, Allow bacterial cells to colonize host tissues, Short appendages

A cell contains a fertility (F) plasmid that allows it to produce a structure for exchanging DNA with another cell. What structure is coded for by the genes of this plasmid?

Pilus

Which external structure directly impacts the effectiveness of the host immune system?

Capsule

True or false: Gram-positive cell walls have a thick layer of peptidoglycan that contributes to their greater strength.

True

True or false: Gram-negative cell walls have a thick layer of peptidoglycan that contributes to their greater strength.

False

True or false: Gram-positive cells have an outer membrane that is easily disrupted by alcohols but does provide resistance to other types of antimicrobial compounds.

False