Quiz 3

Bacterial growth refers to an increase in the number of cells. the occurrence of binary fission. the time required for one cell to divide into two. the occurrence of mitosis.

an increase in the number of cells.

A ________ agent is a chemical that inhibits bacteria from reproducing, but does NOT necessarily kill them. bacteriostatic bacteriolytic bacteriocidal xerophilic

bacteriostatic

Which of the following is/are transferred to daughter cells during bacterial cell division? only the chromosome and enzymes to immediately begin cellular metabolism chromosome, proteins, and all other cellular constituents individual genes and enzymes to later be brought together to form the genome only genomic DNA, the blueprint for everything the cell needs

chromosome, proteins, and all other cellular constituents

The time interval required for the formation of two cells from one is called the growth rate. division rate. growth time. generation time.

generation time.

In a batch culture, bacterial cultures typically exhibit four different phases of growth. In which phase are the cells rapidly synthesizing proteins, but cell numbers are not changing? exponential phase lag phase death phase stationary phase

lag phase

Bacteria that are able to grow in humans and cause disease would be classified as psychrophiles. thermophiles. mesophiles. hyperthermophiles.

mesophiles.

What temperature is most commonly used in autoclaves to sterilize growth media and other devices prior to experimentation? 140°C 95°C 121°C 101°C

121°C

T/F: A bacterium whose optimal growth temperature is 35C would be classified as a thermophile.

False

T/F: Autoclaving and pasteurization are two processes that are both very effective for sterilization.

False

T/F: Horizontally transferred genes typically encode essential metabolic functions such as DNA replication, transcription, and translation.

False

T/F: The optimal pH for growth of an organism refers to its intracellular environment.

False

Which of the following statements is FALSE? In the lag phase, cell death exceeds cell division. In the death phase, bacterial growth may cease as a result of oxygen and nutrient depletion. Bacteria typically divide by binary fission, producing two daughter cells. The generation time of bacteria may vary from species to species.

In the lag phase, cell death exceeds cell division.

What does the minimum inhibitory concentration (MIC) of a chemical tell you? It tells you the lowest concentration of the chemical that is needed to inhibit the growth of a specific microorganism. It tells you the lowest concentration of the chemical that is needed to inhibit the growth of any microorganism. It tells you the lowest concentration of the chemical that is needed to kill a specific microorganism. It tells you the lowest concentration of an organism that is needed for chemical control.

It tells you the lowest concentration of the chemical that is needed to inhibit the growth of a specific microorganism.

A computer program recognizes an ORF by looking for ribosomal binding sites, start codons, and stop codons with an appropriate number of nucleotides between each element. What is a drawback of this approach? Codon bias causes incorrect annotations. We lack the computing power to complete the analyses in a timely manner, thus many genomes are only partially annotated. Legitimate genes and non-coding RNA may be missed. Too many ORFS are identified, most of which are stretches on non-coding junk DNA.

Legitimate genes and non-coding RNA may be missed.

A nurse takes a urine sample from a patient suspected of having contracted a urinary tract infection. The nurse uses careful aseptic technique in collecting the sample. Which is NOT a reason for using aseptic technique in this situation? The nurse wants to avoid contamination of the urine by microbes from the air, the nurse, or the environment. The nurse wants to avoid contamination of the nurse, the patient, or the environment by the urine organisms. The nurse wants to get as many organisms as possible to grow in the culture medium. The nurse wants only the organisms in the urine to be cultured in the medium

The nurse wants to get as many organisms as possible to grow in the culture medium.

An open reading frame (ORF) encodes for a carbohydrate or a polypeptide. a lipid. a carbohydrate. a polypeptide.

a polypeptide.

A microbiology student in a research lab repeated an experiment described by others using the identical bacterial isolate, the same growth medium, and the same growth conditions. However, the student was unable to achieve the same O.D. at 600 nm. What is the LEAST likely cause for this discrepancy in measured turbidity? One experiment subtracted the yellow color of the growth medium away from the final turbidity reported whereas the other used colorless water. One experiment vigorously dispersed the bacterial pellicle with vortexing while the other did not. One experiment used 16 mm wide test tubes while the other used 18 mm wide test tubes. The two experiments were carried out at vastly different elevations and did not consider the influence of pressure.

The two experiments were carried out at vastly different elevations and did not consider the influence of pressure.

T/F: Knowledge of microbial growth patterns is useful in working with the control of microbial growth.

True

T/F: Planktonic cells remain in suspension while sessile cells adhere to a surface.

True

The genome sequence of an organism can provide information about the organism's __________. genes, function, and evolutionary history genes, size, and function function, evolutionary history, and morphology function, size, and evolutionary history

genes, function, and evolutionary history

Genes from different sources that are related in sequence due to shared evolutionary ancestry are called ________ genes, and groups of such genes are known as ________. homologous / gene families orthologous / gene families paralogous / functional genes homologous / functional genes

homologous / gene families

Obligate anaerobes which are sensitive to O2 would be found growing throughout a tube of thioglycolate broth. only at the bottom of a tube of thioglycolate broth. approximately one-third of the way down the thioglycolate broth. only at the very top of a tube of thioglycolate broth.

only at the bottom of a tube of thioglycolate broth.

A student has a pure culture of bacteria growing in a flask and wants to know how many living cells are in the culture at a given time. Which method should she employ to get an estimate? Any of these methods would work equally well in this case, assuming that standard curves are produced. turbidity measurements microscopic counts plate counts

plate counts

The pan genome of a species is the genomic content that is shared with all other prokaryotes. hypothetical or uncharacterized genome content of a species. present in one or more strains of the same species. common to all strains of the same species.

present in one or more strains of the same species.

In Sanger sequencing and in many newer sequencing techniques, labeled precursors are used. What are these precursors? primers or nucleotides that will be incorporated into the newly synthesized DNA DNA polymerase fluorescent dyes RNA

primers or nucleotides that will be incorporated into the newly synthesized DNA

Gene function is annotated based on homology between the ORFs of a genome and proteins whose function has been proven experimentally. What -omic approach could help us determine the function and structure of proteins encoded by uncharacterized ORFs? metagenomics transcriptomics metabolomics proteomics

proteomics

Cultures of a bacterial species were incubated on the shelf of a refrigerator (5°C), on a lab benchtop (25°C), on the shelf of a 37°C incubator, and on the shelf of a 50°C incubator. After incubation, there was no growth at 37°C or 50°C, slight growth on the benchtop, and abundant growth at refrigeration. What term could be used for this species? anaerobe halophile mesophile psychrophile

psychrophile

A microbe growing in a refrigerator is likely mesophilic. hyperthermophilic. psychrotolerant or psychrophilic. psychrophilic.

psychrotolerant or psychrophilic.

Selective medium differs from differential medium because selective medium permits growth of more organisms than differential medium. differential medium differentiates pathogens from nonpathogens while selective medium grows only pathogens. differential medium contains growth inhibitors while selective medium does not. selective medium permits growth of a particular microbial type while differential medium is used to distinguish between types of organisms.

selective medium permits growth of a particular microbial type while differential medium is used to distinguish between types of organisms.

Gene duplication is thought to have had a significant influence on the evolution of microbes because __________. the duplicated gene can be given away to another organism by conjugation the duplicated gene can be mutated, possibly leading to a useful new gene function or product, while the original copy can still perform its original (and possibly essential) genetic function the duplicated gene can allow for increased transcription and synthesis of the gene product the duplicated gene can serve as a "back-up" copy

the duplicated gene can be mutated, possibly leading to a useful new gene function or product, while the original copy can still perform its original