Microbiology Chapters 1,2,3,4 Microorganisms are best defined as organisms that

You have made a smear of a bacterial culture and have performed the Gram stain on it. Looking at the organism under the microscope, you notice that the cells do not seem to be the dark blue purple of a gram-positive reaction, but instead are light purple. Your staining procedure was performed correctly. What is your best explanation as to why the bacteria have stained this way?

A) There is something in the wall of the bacteria that has affected the uptake of the crystal violet into the cell wall, thereby staining it improperly.

Which area of biology states that living things undergo gradual structural and functional changes over long periods of time?

A. Evolution

Which of the following properties are shared by both bacteria and archaea?

A. Single, circular chromosome

A research laboratory that identifies the subspecies of bacterial isolates from a recent Salmonella epidemic would refer to Bergey's Manual of ______ Bacteriology for guidance in identification.

A. Systematic

A microbiologist inoculates Staphylococcus epidermidis and Escherichia coli into a culture medium. Following incubation, only the E. coli grows in the culture. What is the most likely explanation?

A. The culture medium was selective.

Lipopolysaccharide is an important cell envelope component of ______.

A. gram-negative bacteria

A clinical laboratory that identifies the bacterial agents that cause human disease would refer to Bergey's Manual of ______ Bacteriology for guidance in identification.

B. Determinative

Which of the following historical microbiologists is incorrectly paired with his contribution to the science?

B. Louis Pasteur: demonstrated that anthrax was caused by a bacterium

You need to determine if a pure culture of bacteria is gram-positive or gram-negative, but you've just spilled your only solution of crystal violet so you can't do a Gram stain. You decide to try a lysozyme treatment on a sample of each culture and then examine the samples under the microscope. The expected result is

B. gram-positives will lyse and appears as debris; gram-negatives will be unaffected.

A new drug is found to act by blocking the incorporation of subunits into sterol molecules for the cell membrane. Which statement is true?

C. Most bacteria would be unaffected by this drug.

Archaea have been found in many microenvironments in the human body. Which of the following microenvironments is most likely to fit with the designation of Archaea as "extremophiles?"

C. The gingiva and the gut are anaerobic.

You apply the acid-fast stain method to a patient's specimen, an aspirate from the lungs. Microscopic examination reveals a large number of bright pink-red bacillus-shaped bacteria in the smear. Which statement is true?

C. The patient has tuberculosis.

Thioglycolate medium contains the following: yeast extract, pancreatic digest of casein, glucose, L-cysteine, sodium chloride, sodium thioglycolate, and agar. It is considered a complex medium because

C. both yeast extract and pancreatic digest of casein are not chemically defined.

Peptidoglycan is a unique macromolecule found in bacterial ______.

C. cell walls

.Which type of medium distinguishes different types of microorganisms based on an observable change in the colonies or in the medium?

D. Differential

Which of the following are not considered microorganisms?

D. Mosquitoes

A microbiologist inoculates Staphylococcus aureus into a culture medium. Following incubation, both Staphylococcus aureus and Staphylococcus epidermidis are determined to be growing in this culture. What is the most likely explanation?

D. The culture was contaminated.

A common medium for culturing fastidious bacteria is ______.

D. blood agar

A culture of an organism believed to cause intestinal symptoms is viewed under the microscope, and the microbiologist observes a cell membrane, flagella, mitochondria, and some dark unrecognizable structures within each cell. The microbiologist notes that the cells are eukaryotic because

D. only eukaryotic cells have mitochondria.

Researchers studying the rigidity and flexibility of the cell envelope used chemotaxis to measure the ability of microbes to squeeze through tight spaces. E. coli, a gram-negative bacterium, was able to traverse narrower channels than B. subtilis, a gram-positive microbe, even though both cells are the same size when grown without restriction. E. coli has the more flexible cell envelope because

D. there is less structural carbohydrate.

Endospores are

E. All of the choices are correct.

A patient has a serious respiratory infection. A sputum sample yielded a bacterium that did not have any peptidoglycan. You hypothesize that the identity of this microbe could possibly be ______.

E. Mycoplasma pneumoniae

Plasmids

E. often carry genes controlling pathogenicity.

The procedures for culturing a microorganism require the use of a microscope.

FALSE

One technique for staining bacteria for viewing under the microscope is called the Gram stain. In this technique, alcohol is used as a decolorizer because it degrades the outer membrane found in some bacteria. What chemical component of the cell does alcohol affect?

Lipid

Which scientific field is involved in the identification, classification, and naming of organisms?

Taxonomy

If you observe rod-shaped, pink cells on a slide that had just been Gram stained, you can assume that their cell envelope contains endotoxin.

True

Taxonomy does not involve ______.

a common name

Koch's postulates are criteria used to establish that

a specific microbe is the cause of a specific disease.

Sterile refers to ______.

absence of any life forms and viral particles

Agar is an important component of media because

agar provides a solid surface for bacterial growth.

Two functions of bacterial appendages are ______ and ______.

attachment; motility

Organic chemicals always have a basic framework of the element _____ bonded to other atoms.

carbon

The site for ATP synthesis in bacterial cells is the ______.

cell membrane

The subatomic particles that surround the nucleus are the ______.

electrons

Two structures that allow bacteria to adhere to surfaces are ______ and ______.

fimbriae; capsules

Two or more atoms bonded together are called a(n) ______.

molecule

Protons and neutrons make up the atom's central core, which is referred to as its ______.

nucleus

A pure culture contains

only one identified species of microorganism.

Microorganisms are best defined as

organisms that are too small to be seen with the unaided eye.

The lipid group that is the major component of cell membranes is the ______.

phospholipids

The function of bacterial endospores is

protection of genetic material during harsh conditions.

The three physical forms of laboratory media are ______.

solid, semisolid, and liquid

The smallest and most significant taxon is a ______.

species

Serological analysis for bacterial identification typically involves using

specific antibodies to the bacterial cell antigens.

An irregular cluster of spherical bacterial cells is termed ______.

staphylococcus

ATP is best described as

the energy molecule of cells.

The important solvent associated with living things is ______.

water