Question 1

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

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer and teichoic acids, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane containing lipopolysaccharide.

Question 2

A patient is diagnosed with a bacterial infection caused by a spirochete. Which structure is primarily responsible for the motility of this organism?

Accepted Answer

Axial filaments, which allow corkscrew movement.

Question 3

Which of the following statements about the structure and function of the prokaryotic plasma membrane is correct?

Accepted Answer

It is a phospholipid bilayer with embedded proteins, and it is the site of ATP production via the electron transport chain.

Question 4

During glycolysis, what is the net gain of ATP and NADH molecules per molecule of glucose?

Accepted Answer

$2$ ATP and $2$ NADH

Question 5

Which of the following best explains why obligate anaerobes are killed by oxygen?

Accepted Answer

They lack enzymes such as superoxide dismutase and catalase to detoxify reactive oxygen species.

Question 6

A microbiologist wants to isolate a rare bacterium from a soil sample where it is outnumbered by other microbes. Which type of culture medium should be used and why?

Accepted Answer

Enrichment medium, because it enhances the growth of the desired microbe present in small numbers.

Question 7

Which of the following is an example of substrate-level phosphorylation?

Accepted Answer

The direct transfer of a phosphate group from 1,3-bisphosphoglycerate to ADP during glycolysis.

Question 8

A bacterial culture is in the log (exponential) phase of growth. If the generation time is $30$ minutes, how many cells will there be after $3$ hours if you start with $1$ cell? Use the formula $N = N_0 	imes 2^n$, where $n$ is the number of generations.

Accepted Answer

$64$ cells

Question 9

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP stores energy from catabolic reactions and releases it to drive anabolic reactions.

Question 10

Which of the following is a correct pairing of a historical microbiologist and their contribution?

Accepted Answer

Alexander Fleming – Discovered penicillin, the first widely used antibiotic.

Question 11

Which of the following statements about competitive and noncompetitive enzyme inhibition is correct?

Accepted Answer

Competitive inhibitors bind to the active site and can be overcome by increasing substrate concentration, while noncompetitive inhibitors bind to an allosteric site and cannot be overcome by more substrate.

Question 12

A bacterium is classified as a chemoautotroph. Which of the following best describes its energy and carbon sources?

Accepted Answer

It uses inorganic chemicals for energy and CO$_2$ as its carbon source.

Question 13

Which of the following is a function of the Golgi complex in eukaryotic cells?

Accepted Answer

Modifying, sorting, and packaging proteins for transport to the plasma membrane.

Question 14

Which of the following best explains why Mycoplasma species are resistant to antibiotics that target cell wall synthesis?

Accepted Answer

They lack a cell wall and instead have sterols in their plasma membrane.

Question 15

A culture of facultative anaerobes is grown in a test tube. Where would you expect to see the most growth and why?

Accepted Answer

Throughout the tube, but more at the top where oxygen is present, because they can use oxygen but also grow anaerobically.

Question 16

Which of the following is a direct method for measuring bacterial cell growth?

Accepted Answer

Plate count (colony-forming units)

Question 17

Which of the following best describes the process of binary fission in bacteria?

Accepted Answer

The cell elongates, replicates its DNA, forms a cross-wall, and divides into two genetically identical daughter cells.

Question 18

Which of the following is a function of bacterial endospores?

Accepted Answer

Survival under harsh conditions such as heat, radiation, and desiccation.

Question 19

Which of the following best describes the chemiosmotic mechanism of ATP generation?

Accepted Answer

Electrons move through the electron transport chain, pumping protons across the membrane to create a gradient, and ATP synthase uses this gradient to convert ADP and Pi into ATP.

Question 20

A bacterium is found to grow best at $37^{\circ}$C but can survive between $10^{\circ}$C and $47^{\circ}$C. To which temperature group does it belong?

Accepted Answer

Mesophile

Microbiology Study Guide: Cell Structure, Metabolism, Growth, and Historical Foundations

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