Question 1

Which of the following best describes the function of enzymes in microbial metabolism, and how do environmental factors such as pH and temperature affect this function?

Accepted Answer

Enzymes catalyze biochemical reactions by lowering activation energy, but extreme pH and temperature can denature them, reducing their activity.

Question 2

During fermentation, what is the main difference in the end products compared to aerobic respiration, and how does this relate to ATP yield?

Accepted Answer

Fermentation produces organic acids or alcohols and less ATP than aerobic respiration because it does not use the electron transport chain.

Question 3

What does the term 'phosphorylation' mean in cellular metabolism, and which process is an example of substrate-level phosphorylation?

Accepted Answer

Phosphorylation is the addition of a phosphate group to a molecule; substrate-level phosphorylation occurs during glycolysis.

Question 4

Compare the growth requirements of obligate aerobes, obligate anaerobes, and aerotolerant anaerobes. Which of the following statements is correct?

Accepted Answer

Obligate aerobes require oxygen, obligate anaerobes are killed by oxygen, and aerotolerant anaerobes can tolerate but do not use oxygen.

Question 5

Which category would human pathogens best fit in regarding temperature requirements, and why?

Accepted Answer

Mesophiles, because their optimal growth temperature is similar to human body temperature ($\approx 37^\circ C$).

Question 6

Which of the following media types is best used to isolate and identify bacteria that ferment lactose, and why?

Accepted Answer

Differential media, because it distinguishes lactose fermenters by color change.

Question 7

A scientist wants to grow a halophilic, aerobic thermophile. Which of the following conditions would be necessary?

Accepted Answer

High salt concentration, high temperature, and presence of oxygen.

Question 8

What is a biofilm, and where might you commonly find one in a hospital setting?

Accepted Answer

A biofilm is a community of microorganisms attached to a surface, commonly found on catheters and medical devices.

Question 9

Why do bacterial cultures need to be transferred to fresh media often?

Accepted Answer

To replenish nutrients and remove toxic waste products that accumulate over time.

Question 10

Which of the following best explains the difference between sterilization and disinfection?

Accepted Answer

Sterilization kills all forms of microbial life, including spores; disinfection reduces the number of pathogenic organisms but may not kill spores.

Question 11

Which of the following microbes is most resistant to disinfectants, and why?

Accepted Answer

Bacillus, because it forms endospores that are highly resistant.

Question 12

Which of the following is an example of pasteurization, and what is its primary purpose?

Accepted Answer

Heating milk to $72^\circ C$ for 15 seconds to reduce microbial load without sterilizing.

Question 13

Compare the structure and functions of DNA and RNA in microbial cells.

Accepted Answer

DNA is double-stranded and stores genetic information; RNA is single-stranded and functions in protein synthesis.

Question 14

Which of the following best describes the process of transcription in prokaryotes?

Accepted Answer

Transcription is the synthesis of RNA from a DNA template, occurring in the cytoplasm.

Question 15

What type of molecule are genes made of, and what type of molecule do they code for?

Accepted Answer

Genes are made of DNA and code for proteins.

Question 16

How do restriction endonucleases contribute to DNA fingerprinting in microbiology?

Accepted Answer

They cut DNA at specific sequences, generating unique fragment patterns for identification.

Question 17

Which of the following best describes the polymerase chain reaction (PCR) and its significance in microbiology?

Accepted Answer

PCR amplifies specific DNA sequences, allowing detection of pathogens from small samples.

Question 18

A DNA probe is used in a hospital to detect the presence of a specific pathogen in a patient sample. Which property of the DNA probe makes this possible?

Accepted Answer

The probe binds specifically to complementary DNA sequences of the pathogen.

Question 19

Which of the following best explains why obtaining a pure culture from a mixed specimen is important in clinical microbiology?

Accepted Answer

It allows for accurate identification and antibiotic sensitivity testing of the pathogen.

BIO 22 Microbiology Study Guide: Metabolism, Microbial Growth, and Genetics

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