Question 1

Which of the following statements best explains why small prokaryotic cells tend to grow faster than larger ones?

Accepted Answer

Small cells have a higher surface-to-volume ratio, which supports greater nutrient and waste exchange per unit cell volume.

Question 2

A newly discovered marine bacterium is found to be 0.3 μm in diameter and has a highly streamlined genome missing several biosynthetic pathways. What is the most likely ecological strategy of this organism?

Accepted Answer

It is likely an ultramicrobacterium that relies on other microbes or hosts to supply missing functions.

Question 3

Which of the following cell morphologies is most likely to be found in bacteria that exhibit gliding motility?

Accepted Answer

Filamentous

Question 4

Which chemical linkage is found in the membrane lipids of Archaea but not in Bacteria or Eukarya?

Accepted Answer

Ether linkage

Question 5

A bacterial cell is exposed to a chemical that disrupts hydrogen bonds and hydrophobic interactions. Which cell structure is most likely to be affected first?

Accepted Answer

Cytoplasmic membrane

Question 6

Which of the following best describes the function of ABC transport systems in prokaryotes?

Accepted Answer

They consist of a binding protein, a transmembrane transporter, and an ATP-hydrolyzing protein to import specific substrates.

Question 7

Which equation correctly represents the surface-to-volume ratio ($$S/V) $$for a spherical cell of radius $$r$$?

Accepted Answer

$$S/V = \frac{4\pi r^2$}{\frac{4}{3}\pi r^3$}$$

Question 8

Which of the following is NOT a function of the cytoplasmic membrane in prokaryotes?

Accepted Answer

Provides rigid structural support to prevent osmotic lysis

Question 9

A Gram-negative bacterium is found to be resistant to penicillin and lysozyme. Which cell wall component is most likely responsible for this resistance?

Accepted Answer

Lipopolysaccharide (LPS) layer

Question 10

Which of the following transport events involves the simultaneous movement of two molecules in opposite directions across the membrane?

Accepted Answer

Antiport

Question 11

Which of the following best explains why cellular organisms smaller than 0.15 μm in diameter are unlikely to exist?

Accepted Answer

They lack sufficient volume to house essential macromolecules such as proteins, nucleic acids, and ribosomes.

Question 12

Which of the following is a major difference between the cell walls of Bacteria and Archaea?

Accepted Answer

Bacteria have peptidoglycan, while Archaea lack peptidoglycan and may have pseudomurein.

Question 13

Which of the following best describes the arrangement of fatty acids in the bacterial cytoplasmic membrane?

Accepted Answer

Fatty acids point inward to form a hydrophobic environment, while hydrophilic portions face the cytoplasm and external environment.

Question 14

Which of the following is a selective force that may influence prokaryotic cell morphology?

Accepted Answer

Optimization for nutrient uptake in small cells with high surface-to-volume ratio

Question 15

Which of the following statements about carrier-mediated transport systems is TRUE?

Accepted Answer

They show high sensitivity and specificity for their substrates.

Question 16

Which of the following is a correct description of the phosphotransferase system in E. coli?

Accepted Answer

It is a group translocation system that chemically modifies the transported substance using energy from phosphoenolpyruvate.

Question 17

Which of the following is a function of the outer surface of the cytoplasmic membrane?

Accepted Answer

Binds substrates or processes large molecules for transport

Question 18

Which of the following is a correct statement about the lipid composition of archaeal membranes?

Accepted Answer

Archaeal membranes contain isoprenoid chains bound to glycerol by ether bonds.

Question 19

Which of the following is a correct description of the arrangement of cell wall layers in Gram-negative bacteria?

Accepted Answer

An outer membrane composed of LPS and a thin layer of peptidoglycan

Microbial Cell Structure and Function: Study Notes for BIOL 305

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