Q: Which equation best represents the exponential growth of bacteria in batch culture?

$$N = N_0$ \times e$$^{\mu t}$$

Question 1

Which of the following best explains why small cell size is advantageous for microbes?

Accepted Answer

Small cells have a higher surface area-to-volume ratio, which increases the rate of diffusion of nutrients and waste products.

Question 2

A microbiologist wants to distinguish between Gram-positive and Gram-negative bacteria in a clinical sample. Which laboratory technique should they use, and what is the key difference observed?

Accepted Answer

Use the Gram stain; Gram-positive bacteria appear purple due to a thick peptidoglycan layer, while Gram-negative appear pink due to a thin peptidoglycan layer and an outer membrane.

Question 3

Which of the following statements about the cell envelope of archaea is correct?

Accepted Answer

Archaeal cell envelopes often contain pseudopeptidoglycan and ether-linked lipids, distinguishing them from bacterial cell envelopes.

Question 4

Which equation best represents the exponential growth of bacteria in batch culture?

Accepted Answer

$$N = N_0$ 	imes e$$^{\mu t}$$

Question 5

A scientist is studying a bacterium that can survive extreme heat and high salinity. Which terms best classify this organism?

Accepted Answer

Thermophile and halophile

Question 6

Which of the following is a major difference between prokaryotic and eukaryotic flagella?

Accepted Answer

Prokaryotic flagella rotate, powered by proton motive force, while eukaryotic flagella whip back and forth, powered by ATP.

Question 7

Which of the following best describes the endosymbiotic theory?

Accepted Answer

Mitochondria and chloroplasts originated from prokaryotic cells that were engulfed by ancestral eukaryotic cells and became organelles.

Question 8

Which of the following statements about ATP generation is correct?

Accepted Answer

Substrate-level phosphorylation generates ATP directly from ADP and a phosphorylated substrate.

Question 9

A fermentative organism achieves redox balance by:

Accepted Answer

Transferring electrons to organic molecules, such as pyruvate, to regenerate NAD$$^+.$$

Question 10

Which of the following best describes the proton motive force (PMF) in prokaryotes?

Accepted Answer

PMF is generated by the movement of protons across the cytoplasmic membrane, creating an electrochemical gradient used to drive ATP synthesis.

Question 11

Which of the following is a key difference between complex and defined media?

Accepted Answer

Defined media contains precisely known chemical composition, while complex media contains ingredients of unknown composition such as yeast extract.

Question 12

Which of the following is NOT a major step in biofilm formation?

Accepted Answer

Direct lysis of host cells by biofilm enzymes

Question 13

Which of the following best explains why viruses are considered obligate intracellular parasites?

Accepted Answer

Viruses require host cell machinery to replicate their genome and produce new virions.

Question 14

Which of the following best describes the structure of a coronavirus virion?

Accepted Answer

Enveloped, helical nucleocapsid, single-stranded RNA genome

Question 15

Which proteins are directly involved in the bacterial SOS response to DNA damage?

Accepted Answer

RecA and LexA

Question 16

Which of the following best describes a frameshift mutation?

Accepted Answer

A mutation caused by insertion or deletion of nucleotides not in multiples of three, altering the reading frame and often producing a nonfunctional protein.

Question 17

Which of the following is a major mechanism by which bacteria avoid destruction by viruses?

Accepted Answer

Production of CRISPR-Cas systems that recognize and degrade viral DNA.

Question 18

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

DNA is transcribed to RNA, which is translated to protein.

Question 19

Which of the following is a correct sequence of the five steps in the viral replication cycle of T4 phage?

Accepted Answer

Attachment, penetration, synthesis, assembly, release

Question 20

Which of the following best describes the role of chaperone proteins in bacteria?

Accepted Answer

Chaperone proteins assist in the proper folding of newly synthesized polypeptides and prevent aggregation.

MCB3020 Midterm Study Guide: Core Concepts in Microbiology

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