Question 1

Which molecule is primarily used to determine the evolutionary relationships among Bacteria, Archaea, and Eukarya in the modern 'Tree of Life'?

Accepted Answer

16S rRNA gene sequences

Question 2

A bacterium with a thick peptidoglycan cell wall and no outer membrane is most likely classified as:

Accepted Answer

Gram-positive

Question 3

Which bacterial cell structure is responsible for motility and is often used to move toward nutrients or away from toxins?

Accepted Answer

Flagella

Question 4

In the bacterial life cycle, what is the correct sequence of events leading to biofilm formation?

Accepted Answer

Planktonic cells attach to a surface, aggregate, secrete extracellular polysaccharides, and mature into a biofilm

Question 5

Which of the following is NOT an advantage for bacteria living in a biofilm?

Accepted Answer

Increased predation by amoeba and other Eukaryotic microbes

Question 6

Dental plaque is an example of a biofilm. What is a major medical consequence of dental plaque?

Accepted Answer

Dental caries and periodontal disease

Question 7

Which bacterial arrangement is illustrated by a chain of cocci?

Accepted Answer

Streptococcus

Question 8

What is the primary function of the bacterial capsule?

Accepted Answer

Protection against desiccation and immune evasion

Question 9

Which staining method is used to visualize bacterial endospores?

Accepted Answer

Schaeffer-Fulton staining

Question 10

A pilot study in Bangladesh showed a reduction in cholera cases by filtering water with sari cloth. What is the most likely mechanism for this reduction?

Accepted Answer

Sari cloth traps Vibrio cholerae bacteria and biofilm particles

Question 11

Which phase in the bacterial growth curve is characterized by exponential increase in cell number?

Accepted Answer

Log phase

Question 12

Actinomycetes are often mistaken for fungi because they:

Accepted Answer

Form filamentous structures and produce spores

Question 13

Which of the following statements about biofilms is TRUE?

Accepted Answer

There is often metabolic cooperation among bacteria in biofilms

Question 14

Which bacterial cell shape is described as 'curved rod'?

Accepted Answer

Vibrio

Question 15

What is the main reason biofilms are problematic in medical devices such as catheters?

Accepted Answer

Biofilms increase resistance to antibiotics and immune clearance

Question 16

Which equation best describes exponential bacterial growth during the log phase?

Accepted Answer

$$N_t = N_0$ 	imes 2$$^{n}$$

Question 17

Which of the following is a real-world example of a biofilm causing disease?

Accepted Answer

Pseudomonas aeruginosa biofilms in cystic fibrosis lungs

Question 18

Which bacterial cell arrangement is illustrated by a cluster of cocci?

Accepted Answer

Staphylococcus

Question 19

Which of the following is a characteristic of Gram-negative bacteria?

Accepted Answer

Thin peptidoglycan layer and an outer membrane

Question 20

Which of the following best describes the role of extracellular polysaccharides in biofilm formation?

Accepted Answer

They form a matrix that holds cells together and protects against environmental stress

lecture 10

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