Q: Which group of microbes is most likely to spoil refrigerated food, and what is their preferred temperature range?

Psychrotrophs; $0\text{--}30^\circ\mathrm{C}$

Q: Which of the following best describes the central dogma of molecular biology?

$\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$

Question 1

Which group of microbes is most likely to spoil refrigerated food, and what is their preferred temperature range?

Accepted Answer

Psychrotrophs; $0	ext{--}30^\circ\mathrm{C}$

Question 2

A bacterium is placed in a hypertonic environment. What is the most likely outcome for the cell?

Accepted Answer

The cell will undergo plasmolysis, losing water and shrinking.

Question 3

Which element is primarily required for the synthesis of nucleic acids and ATP in microbial cells?

Accepted Answer

Phosphorus

Question 4

A microbe grows equally well in the presence or absence of oxygen. How would you classify it?

Accepted Answer

Aerotolerant anaerobe

Question 5

Which enzyme allows aerobes to detoxify superoxide radicals ($\mathrm{O}_2^-$)?

Accepted Answer

Superoxide dismutase

Question 6

Biofilm formation provides bacteria with which advantage, and why is this problematic for humans?

Accepted Answer

Protection from environmental stress; it makes infections harder to treat.

Question 7

During which phase of the bacterial growth curve is the population size constant, and what is the main reason for this?

Accepted Answer

Stationary phase; nutrient depletion and waste accumulation balance cell division and death.

Question 8

If a bacterial culture has a generation time of 30 minutes, how many cells will there be after 3 hours if you start with 100 cells? Use the formula $N = N_0 	imes 2^n$, where $n$ is the number of generations.

Accepted Answer

6400 cells

Question 9

Which method is considered an indirect measurement of microbial growth and relies on light absorption?

Accepted Answer

Turbidity

Question 10

Which physical method of microbial control is most effective for sterilizing heat-sensitive solutions, such as vaccines?

Accepted Answer

Filtration

Question 11

Ionizing radiation kills cells primarily by:

Accepted Answer

Causing mutations in DNA

Question 12

Which term describes the complete removal or destruction of all forms of microbial life, including endospores?

Accepted Answer

Sterilization

Question 13

During DNA replication, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Question 14

What supplies the energy needed for DNA replication?

Accepted Answer

The breaking of phosphate bonds in nucleoside triphosphates

Question 15

Which process involves the conversion of DNA to mRNA?

Accepted Answer

Transcription

Question 16

In prokaryotes, which structure allows for simultaneous transcription and translation?

Accepted Answer

Ribosome

Question 17

Which type of operon is typically turned off but can be activated in the presence of a specific substrate?

Accepted Answer

Inducible operon

Question 18

Horizontal gene transfer in bacteria can occur via all of the following EXCEPT:

Accepted Answer

Binary fission

Question 19

A bacterium acquires antibiotic resistance by receiving a plasmid from another cell. This is an example of:

Accepted Answer

Horizontal gene transfer

Question 20

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$

Microbial Growth, Control, and Genetics: Study Guide for BIO 203 Exam 2

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