Question 1

Which of the following best describes the purpose of streak plating in microbiology labs?

Accepted Answer

To isolate individual bacterial colonies from a mixed culture by spreading cells across an agar surface.

Question 2

During a DNA extraction from strawberries, which reagent is primarily responsible for dissolving the phospholipid bilayers of cell and nuclear membranes?

Accepted Answer

Dish soap (detergent)

Question 3

In a centrifuge, what is the main safety concern when balancing tubes, and what is the consequence of improper balancing?

Accepted Answer

Ensuring tubes are placed symmetrically; improper balancing can cause excessive vibration and potential equipment damage.

Question 4

Which of the following best defines the term 'supernatant' in a DNA extraction protocol?

Accepted Answer

The liquid above the pellet after centrifugation, containing dissolved substances.

Question 5

Which reaction is exergonic and typically releases ATP in microbial metabolism?

Accepted Answer

Hydrolytic reactions

Question 6

An enzyme acts as a biological catalyst by:

Accepted Answer

Decreasing the activation energy, speeding up the reaction without being consumed.

Question 7

Which factor is most likely to denature an enzyme, rendering it inactive?

Accepted Answer

Extreme changes in pH or temperature.

Question 8

In the central dogma of molecular biology, which step is analyzed by 'transcriptomics'?

Accepted Answer

Transcription

Question 9

A mutation in the DNA sequence can impact which subsequent step in the central dogma?

Accepted Answer

Transcription and translation, potentially altering RNA and protein products.

Question 10

Which statement best describes a repressible operon?

Accepted Answer

It is usually on but can be turned off when a specific molecule (corepressor) is present.

Question 11

Which of the following is NOT a difference between prokaryotic and eukaryotic RNA?

Accepted Answer

Prokaryotic RNA contains introns that are removed during processing.

Question 12

Which process involves the transfer of genetic material from one bacterium to another via a pilus?

Accepted Answer

Conjugation

Question 13

In Griffith's experiment, what was the key finding regarding transformation?

Accepted Answer

Non-virulent bacteria became virulent when mixed with heat-killed virulent bacteria, demonstrating uptake of genetic material.

Question 14

Which phase of a bacteriophage life cycle results in the destruction of the host cell?

Accepted Answer

Lytic phase

Question 15

Which of the following best describes a plasmid with an R factor?

Accepted Answer

A plasmid that carries genes for antibiotic resistance.

Question 16

Transposons are mobile genetic elements. Which is a potential disadvantage of transposon activity in a bacterial genome?

Accepted Answer

They can disrupt essential genes, leading to loss of function.

Question 17

In PCR, what is the purpose of the heating step?

Accepted Answer

To denature the DNA, separating the strands.

Question 18

Which method is used to introduce foreign DNA into cells by creating temporary pores in the membrane using an electric field?

Accepted Answer

Electroporation

Question 19

Amplicon sequencing differs from shotgun sequencing in that:

Accepted Answer

Amplicon sequencing targets specific regions of DNA, while shotgun sequencing randomly fragments and sequences the entire genome.

Question 20

A student is performing a DNA extraction and observes that no DNA is visible after adding ice-cold ethanol. Which troubleshooting step should they try first?

Accepted Answer

Ensure the ethanol is sufficiently cold and at the correct concentration (70-90%).

Microbiology Lab Concepts and Molecular Genetics Study Guide

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