Q: During the bacterial growth curve, which phase is characterized by exponential increase in cell number, and what is the formula for calculating the number of cells after $$n$$ generations?

Log (exponential) phase; $$N = N_0$ \times 2^n$$

Question 1

Which of the following best describes a biofilm and its significance in clinical settings?

Accepted Answer

A biofilm is a community of microorganisms attached to a surface, embedded in a self-produced matrix; it is significant because it increases resistance to antimicrobial agents.

Question 2

Which category of bacteria would most likely thrive in an environment with no oxygen, and what is the term for this group?

Accepted Answer

Obligate anaerobes; they cannot survive in the presence of oxygen.

Question 3

A microbiologist wants to isolate a bacterium that can metabolize lactose. Which type of medium should she use, and why?

Accepted Answer

Differential medium, because it allows visualization of metabolic differences such as lactose fermentation.

Question 4

During the bacterial growth curve, which phase is characterized by exponential increase in cell number, and what is the formula for calculating the number of cells after $$n$$ generations?

Accepted Answer

Log (exponential) phase; $$N = N_0$ 	imes 2^n$$

Question 5

Which of the following best distinguishes between sterilization and disinfection?

Accepted Answer

Sterilization removes all microbes including endospores, while disinfection reduces microbial numbers but may not kill endospores.

Question 6

A hospital is concerned about a bacterial strain that survives exposure to common disinfectants. Which microbial characteristic most likely contributes to this resistance?

Accepted Answer

Ability to form endospores.

Question 7

Which statement correctly differentiates genotype and phenotype in bacteria?

Accepted Answer

Genotype is the sequence of DNA, while phenotype is the expression of traits resulting from the genotype.

Question 8

Which of the following best describes the sequence of events in DNA replication in prokaryotes?

Accepted Answer

Initiation at the origin, elongation by DNA polymerase, termination at the terminus.

Question 9

A mutation changes a single nucleotide in a gene, resulting in a different amino acid in the protein. What type of mutation is this, and what effect might it have?

Accepted Answer

Missense mutation; may alter protein function depending on the amino acid change.

Question 10

Which process involves the transfer of genetic material from one bacterium to another via a pilus, and what is its significance?

Accepted Answer

Conjugation; enables horizontal gene transfer and spread of antibiotic resistance.

Question 11

Which of the following best describes the role of plasmids in bacterial evolution?

Accepted Answer

Plasmids carry genes that can confer advantages such as antibiotic resistance, facilitating genetic change over time.

Question 12

Which of the following is a basic mechanism of action for microbial control agents?

Accepted Answer

Inhibition of cell wall synthesis, leading to cell lysis.

Question 13

A scientist uses restriction enzymes to cut DNA at specific sequences. Which biotechnology tool is she using, and what is the purpose?

Accepted Answer

Restriction enzymes; to create recombinant DNA by cutting at specific sites.

Question 14

Which equation represents the amplification of DNA during PCR after $$n$$ cycles, starting with one copy?

Accepted Answer

$$N = 2^n$$

Question 15

Which method is commonly used to insert foreign DNA into eukaryotic cells for genetic engineering?

Accepted Answer

Electroporation, which uses an electric field to increase cell membrane permeability.

Question 16

Which of the following is an ethical concern associated with biotechnology research?

Accepted Answer

Potential for creating antibiotic-resistant organisms.

Question 17

A bacterial cell acquires a gene for antibiotic resistance from another cell via transformation. What is the most likely mechanism?

Accepted Answer

Uptake of naked DNA from the environment.

Question 18

Which of the following best describes the difference between horizontal and vertical gene transfer in microbes?

Accepted Answer

Horizontal transfer involves gene exchange between cells of the same generation, while vertical transfer is from parent to offspring.

Question 19

Which of the following is an example of a chemically defined medium?

Accepted Answer

Glucose salts medium, where all components and their concentrations are known.

Microbiology Study Guide: Concepts and Processes

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