Question 1

Which of the following best describes Koch’s Postulates and their significance in microbiology?

Accepted Answer

They are a set of criteria used to establish a causative relationship between a microbe and a disease.

Question 2

Pasteur’s experiment with the swan-neck flask disproved which widely held belief?

Accepted Answer

Spontaneous generation of life from non-living matter.

Question 3

Which of the following statements about the cytoplasmic membrane is FALSE?

Accepted Answer

It is identical in structure and composition in Bacteria, Archaea, and Eukarya.

Question 4

Why is it advantageous for unicellular osmotrophic cells to be small?

Accepted Answer

A small size increases the surface area-to-volume ratio, enhancing nutrient uptake by diffusion.

Question 5

Which of the following best describes the difference between Gram-positive and Gram-negative bacteria?

Accepted Answer

Gram-negative bacteria have an outer membrane and a thin peptidoglycan layer, while Gram-positive bacteria lack an outer membrane and have a thick peptidoglycan layer.

Question 6

A bacterium is found to move toward a chemical attractant. This behavior is best described as:

Accepted Answer

Chemotaxis

Question 7

Which of the following equations correctly describes exponential population growth in bacteria, where $$N is $$the final cell number, $$N_0 is $$the initial cell number, and $$n is $$the number of generations?

Accepted Answer

$$N = N_0$ 2^n$$

Question 8

Which of the following best explains the role of the proton motive force (PMF) in bacterial cells?

Accepted Answer

It drives ATP synthesis, solute transport, and flagellar rotation.

Question 9

A culture of bacteria is growing in a chemostat. Which of the following is true about the growth phase in a chemostat?

Accepted Answer

Cells are maintained in a continuous exponential (log) phase.

Question 10

Which of the following statements about viruses is TRUE?

Accepted Answer

Viruses are not considered cellular life because they lack metabolism and cannot reproduce independently.

Question 11

A virus infects a bacterial cell and integrates its genome into the host chromosome, remaining dormant for several generations. This is an example of which viral life cycle?

Accepted Answer

Lysogenic (temperate) cycle

Question 12

Which of the following best describes the function of an operon in prokaryotic gene regulation?

Accepted Answer

A cluster of genes transcribed as a single mRNA under the control of a single promoter.

Question 13

Which of the following is an example of negative transcriptional control by induction?

Accepted Answer

The lac operon is activated in the presence of lactose, which inactivates the repressor.

Question 14

Which of the following best describes quorum sensing in bacteria?

Accepted Answer

A process where bacteria communicate using chemical signals to coordinate group behaviors based on population density.

Question 15

A bacterial strain is unable to synthesize the amino acid histidine and requires it to be supplied in the growth medium. This strain is best described as:

Accepted Answer

An auxotroph

Question 16

Which of the following best describes the process of conjugation in bacteria?

Accepted Answer

Direct transfer of DNA from one cell to another via a pilus.

Question 17

Which of the following is a correct statement about the difference between substrate-level phosphorylation and oxidative phosphorylation?

Accepted Answer

Substrate-level phosphorylation directly transfers a phosphate group to ADP, while oxidative phosphorylation uses a proton gradient and ATP synthase.

Question 18

A mutation changes a single nucleotide in a gene, resulting in a codon that specifies a different amino acid. This is an example of:

Accepted Answer

Missense mutation

Question 19

Which of the following best describes the function of ABC transporters in bacterial cells?

Accepted Answer

They use ATP hydrolysis to actively transport substances across the membrane.

Question 20

Which of the following is a plausible reason why prokaryotes exhibit greater catabolic diversity than eukaryotes?

Accepted Answer

Prokaryotes have evolved to exploit a wider range of energy and carbon sources due to their diverse habitats.

Microbiology Study Guide: Key Concepts for MAR 301 Mid-Term I

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