Q: Which formula best represents the repeating unit of peptidoglycan?

$$\text{NAG} - \beta(1,4) - \text{NAM}$$

Q: According to the endosymbiotic theory, which equation best represents the origin of mitochondria?

$$\text{Primitive Eukaryote} + \text{Aerobic Prokaryote} \rightarrow \text{Eukaryote with Mitochondria}$$

Question 1

Which structural feature distinguishes Gram-positive from Gram-negative bacterial cell walls?

Accepted Answer

Gram-positive cell walls contain a thick layer of peptidoglycan and teichoic acids, while Gram-negative cell walls have a thin peptidoglycan layer and an outer membrane containing lipopolysaccharides.

Question 2

What is the basic structure of peptidoglycan in bacterial cell walls?

Accepted Answer

Peptidoglycan consists of repeating units of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) linked by β-1,4 glycosidic bonds, with peptide cross-links between the NAM residues.

Question 3

Which extracellular structure allows bacteria to adhere to surfaces and form biofilms, and what is its primary composition?

Accepted Answer

Fimbriae, composed mainly of protein subunits called pilin.

Question 4

Which extracellular structure in eukaryotic cells is responsible for cell movement and is composed of microtubules arranged in a '9+2' pattern?

Accepted Answer

Cilia

Question 5

Which internal structure is found in eukaryotes but not in prokaryotes, and is responsible for energy production?

Accepted Answer

Mitochondria

Question 6

What is the primary role of lipids in the plasma membrane?

Accepted Answer

Lipids form a bilayer that acts as a selective barrier, regulating the movement of substances into and out of the cell.

Question 7

Which arrangement of flagella is described by a single flagellum at one end of the cell?

Accepted Answer

Monotrichous

Question 8

A bacterium with a spherical shape arranged in clusters is best described as:

Accepted Answer

Staphylococcus

Question 9

Which organelle in eukaryotic cells is responsible for protein synthesis and can be found attached to the endoplasmic reticulum?

Accepted Answer

Ribosome

Question 10

According to the endosymbiotic theory, which organelle is believed to have originated from a symbiotic relationship between a primitive eukaryotic cell and a prokaryotic cell?

Accepted Answer

Mitochondria

Question 11

A patient is diagnosed with a bacterial infection. The bacteria are rod-shaped and arranged in chains. Which term best describes this bacterial morphology?

Accepted Answer

Streptobacillus

Question 12

Which formula best represents the repeating unit of peptidoglycan?

Accepted Answer

$$	ext{NAG} - \beta(1,4) - 	ext{NAM}$$

Question 13

Which bacterial extracellular structure is primarily involved in conjugation and transfer of genetic material?

Accepted Answer

Pilus

Question 14

Which eukaryotic organelle is responsible for modifying, sorting, and packaging proteins for secretion?

Accepted Answer

Golgi apparatus

Question 15

Which arrangement of flagella describes multiple flagella at one end of the cell?

Accepted Answer

Lophotrichous

Question 16

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

Accepted Answer

Protein synthesis

Question 17

Which internal structure is present in prokaryotes but absent in eukaryotes?

Accepted Answer

Nucleoid

Question 18

Which lipid component is most responsible for the fluidity of the plasma membrane?

Accepted Answer

Unsaturated fatty acids

Question 19

Which bacterial shape is described as spiral and flexible?

Accepted Answer

Spirochete

Question 20

According to the endosymbiotic theory, which equation best represents the origin of mitochondria?

Accepted Answer

$$	ext{Primitive Eukaryote} + 	ext{Aerobic Prokaryote} ightarrow 	ext{Eukaryote with Mitochondria}$$

Microbiology Study Guide: Cell Structure, Function, and Theory

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