Question 1

Which of the following best distinguishes a prion from a virus and a viroid?

Accepted Answer

Prions are infectious proteins, while viruses and viroids contain nucleic acids.

Question 2

A virus with a helical structure is most likely to appear as:

Accepted Answer

A rod-like shape

Question 3

Why is the type of viral genome (DNA or RNA, single or double stranded) important for the replication mechanism?

Accepted Answer

It determines which enzymes are needed for replication and how the genome is copied.

Question 4

During the viral life cycle, which step involves the synthesis of viral proteins using the host cell machinery?

Accepted Answer

Synthesis

Question 5

Which of the following best describes the difference between the lytic and lysogenic cycles in bacteriophages?

Accepted Answer

Lytic cycle results in cell lysis and release of new virions, while lysogenic cycle involves integration of phage DNA into the host genome.

Question 6

Bacteriophages are considered a promising treatment for bacterial infections in humans because:

Accepted Answer

They target specific bacterial receptors that are absent in human cells.

Question 7

Which type of viral infection in animal cells is most likely to result in cancerous transformation?

Accepted Answer

Transformation

Question 8

An animal virus enters a cell by membrane fusion. What is the next critical step for the virus to begin replication?

Accepted Answer

Uncoating of the viral genome

Question 9

Which viral enzyme is commonly packaged in retroviruses and is essential for converting viral RNA into DNA?

Accepted Answer

Reverse transcriptase

Question 10

Viral budding is important in virion formation because:

Accepted Answer

It allows the virus to acquire a lipid envelope from the host cell membrane.

Question 11

Which of the following correctly matches the structure and host of an acellular infectious agent?

Accepted Answer

Viroids are naked RNA molecules that infect plants.

Question 12

During binary fission, which equation best describes the increase in bacterial cell number over time?

Accepted Answer

$$N = N_0$ 	imes 2^n$$

Question 13

Which stage of the bacterial growth curve is characterized by rapid cell division and exponential increase in cell number?

Accepted Answer

Log (exponential) phase

Question 14

A bacterium that grows only in the absence of oxygen is best described as:

Accepted Answer

Obligate anaerobe

Question 15

If a microorganism grows optimally at $$37^\circC $$and neutral pH, it is most likely classified as:

Accepted Answer

Mesophile and neutrophile

Question 16

How do environmental preferences and metabolic abilities impact pathogen development and survival?

Accepted Answer

They determine where pathogens can thrive and cause disease based on available nutrients and conditions.

Question 17

Which of the following best describes the relationship between enzymes, active sites, substrates, and products?

Accepted Answer

Enzymes bind substrates at their active sites and convert them into products.

Question 18

An enzyme speeds up a chemical reaction by:

Accepted Answer

Lowering the activation energy ($$E_a) $$required for the reaction.

Question 19

Which mechanism of enzyme regulation involves a molecule binding to a site other than the active site, causing a change in enzyme activity?

Accepted Answer

Allosteric regulation

Question 20

A bacterial enzyme is most active at pH 7 and $$37^\circC. $$What would likely happen if the enzyme is exposed to pH 3 and $$60^\circC$$?

Accepted Answer

The enzyme would denature and lose activity.

Acellular Infectious Agents, Viral Life Cycles, and Microbial Growth: Study Notes

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