Question 1

Which of the following best describes the function of siderophores in bacterial nutrient uptake?

Accepted Answer

They bind and transport ferric ion ($$Fe^{3+}) $$into the cell, where it is reduced to ferrous ion ($$Fe^{2+}).$$

Question 2

A bacterium is transferred from a complex medium to a minimal medium. Which phase of the growth curve is most likely to be prolonged as a result?

Accepted Answer

Lag phase

Question 3

Which of the following transport mechanisms is unique to prokaryotes and involves chemical modification of the substrate during transport?

Accepted Answer

Group translocation

Question 4

A culture of E. coli is growing in a chemostat at steady state. Which of the following best describes the relationship between dilution rate ($$D$$), cell mass ($$X$$), and generation time ($$g$$)?

Accepted Answer

As the dilution rate ($$D) $$increases, the generation time ($$g) $$decreases and cell mass ($$X) $$remains constant until washout.

Question 5

Which of the following statements about ABC transporters is FALSE?

Accepted Answer

They are found only in prokaryotes.

Question 6

A bacterial culture is started with 1 cell. If the generation time is 30 minutes, how many cells will there be after 3 hours, assuming all cells remain viable and divide by binary fission?

Accepted Answer

$$2^6 = 64$ cells

Question 7

Which of the following best explains why only about 0.1% of microorganisms from the environment have been successfully cultured in the laboratory?

Accepted Answer

Most microbes require complex, multispecies interactions or specific growth conditions not replicated in the lab.

Question 8

Which of the following is the fastest method for estimating cell density in a liquid culture?

Accepted Answer

Spectrophotometer (measuring optical density)

Question 9

Which of the following best describes the sequence of events in biofilm formation?

Accepted Answer

Quorum sensing $$\rightarrow$$ twitching motility $$\rightarrow$$ microcolony formation $$\rightarrow$$ exopolysaccharide formation

Question 10

Which of the following types of media is correctly matched with its description?

Accepted Answer

Selective media—favor the growth of one organism over another

Question 11

Which of the following is a real-world example of group translocation in bacteria?

Accepted Answer

The phosphotransferase system (PTS) in $$E. coli$$ that uses phosphoenolpyruvate (PEP) to phosphorylate glucose during transport.

Question 12

Which of the following bacteria does NOT undergo cell differentiation?

Accepted Answer

Staphylococcus

Question 13

A patient is infected with $$Neisseria$$ $$gonorrhoeae. $$Which adaptation allows this bacterium to acquire iron from the human host?

Accepted Answer

It expresses surface receptors that bind human iron complexes and extract iron.

Question 14

Which of the following best describes the function of efflux ABC transporters in bacteria?

Accepted Answer

They export toxic compounds, such as antibiotics, out of the cell.

Question 15

Which of the following is a key feature of exponential growth in bacteria?

Accepted Answer

The number of cells increases according to $$N = N_0$ 	imes 2^n$$, where $$n is $$the number of generations.

Question 16

Which of the following is a function of heterocysts in cyanobacteria such as $$Anabaena$$?

Accepted Answer

They fix nitrogen anaerobically while maintaining oxygenic photosynthesis in neighboring cells.

Question 17

Which of the following best explains why biofilms are medically significant in chronic infections?

Accepted Answer

Biofilms protect bacteria from antibiotics and the immune system, making infections harder to eradicate.

Question 18

Which of the following is NOT a step in endospore formation in $$Bacillus$$ species?

Accepted Answer

Symmetrical cell division producing two identical daughter cells

Question 19

A researcher wants to isolate a single bacterial species from a mixed environmental sample. Which technique is most appropriate?

Accepted Answer

Dilution streaking on solid agar

Bacterial Culture, Growth, and Development: Structured Study Notes

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