Question 1

Which of the following structures is responsible for motility in most bacteria, and what is the primary energy source driving its rotation?

Accepted Answer

Flagella; powered by proton motive force ($$\Delta p)$$

Question 2

A bacterium is observed to move toward a nutrient source. Which process best describes this behavior, and what is the underlying mechanism?

Accepted Answer

Chemotaxis; alternating runs (CCW) and tumbles (CW) based on chemical gradients

Question 3

Which specialized structure allows certain bacteria to orient themselves along magnetic fields, and what is its chemical composition?

Accepted Answer

Magnetosome; composed of membrane-embedded crystals of $$Fe_3O_4$$

Question 4

Which of the following is NOT a function of bacterial pili?

Accepted Answer

Energy production via ATP synthesis

Question 5

Gram-negative bacteria differ from Gram-positive bacteria in which structural feature?

Accepted Answer

Presence of an outer membrane containing lipopolysaccharide (LPS)

Question 6

Which process allows bacteria to take up nutrients against their concentration gradient, and what is the general equation for ATP hydrolysis involved?

Accepted Answer

Active transport; $$ATP \rightarrow ADP + P_i$$

Question 7

Which of the following is a major macronutrient required for microbial growth and is a key component of proteins?

Accepted Answer

Nitrogen ($$N)$$

Question 8

A bacterium uses substrate-specific carrier proteins to import glucose. What type of membrane transport is this, and does it require energy?

Accepted Answer

Facilitated diffusion; does not require energy

Question 9

Which structure is primarily responsible for the selective permeability of the bacterial cell, and what are the three main mechanisms by which it achieves this?

Accepted Answer

Cell membrane; substrate-specific carrier proteins, nutrient-binding proteins, and protein channels/pores

Question 10

Which of the following best describes the function of siderophores in bacteria?

Accepted Answer

They scavenge iron from the environment and facilitate its uptake into the cell

Question 11

Which type of ABC transporter is primarily involved in multidrug resistance in bacteria?

Accepted Answer

Efflux ABC transporter

Question 12

During chemotaxis, what is the difference between a 'run' and a 'tumble' in bacterial movement?

Accepted Answer

'Run' is counterclockwise (CCW) flagellar rotation leading to straight movement; 'tumble' is clockwise (CW) rotation causing random reorientation

Question 13

Which of the following is a micronutrient required for enzyme function in bacteria?

Accepted Answer

Copper ($$Cu)$$

Question 14

What is the main difference in the cell envelope structure between Archaea and Bacteria?

Accepted Answer

Archaea lack peptidoglycan in their cell walls

Question 15

Which process involves the transformation of substrates by phosphorylation during transport, and what is the key molecule donating the phosphate group?

Accepted Answer

Group translocation; phosphoenolpyruvate ($$PEP)$$

Question 16

Which specialized structure in cyanobacteria is responsible for photosynthesis?

Accepted Answer

Thylakoid

Question 17

A bacterium is observed to have numerous vesicles released from its membrane. What is a possible function of these membrane vesicles?

Accepted Answer

Transport of toxins, communication, and nutrient acquisition

Question 18

Which structure is essential for the exchange of genetic material between bacterial cells, and what is the process called?

Accepted Answer

Pili; conjugation

Question 19

Which of the following best describes the function of carboxysomes in bacteria?

Accepted Answer

They concentrate CO$$_2$$ for carbon fixation

Bacterial Cell Structure, Specialized Structures, and Nutrient Uptake

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