Tutorial Microbial World Final

The generation time of a microorganism is also known as the doubling time. This statement is _____

• True

• False

Bacteria that grow in mine drainage at pH 1–2 are probably alkaliphiles. This statement is _____ 

• False

• True

Which of the following is the reason jams and dried meats often do not require refrigeration to prevent spoilage?

• Low water activity.

• Toxic alkaline chemicals.

• Presence of naturally occurring antibiotics

• Low pH.

Which of the following cannot be sterilised by dry heat? 

• Water

• Metal

• Oil

• Wax

From the list below, the most resistant to chemical disinfectants are the _____

• Endospores of bacteria

• Non-enveloped viruses

• Gram positive bacteria

• Gram negative bacteria

A protein that binds to the operator and blocks the RNA polymerase is called a(n) _____

• repressor.

• inhibitor

• blocker.

• regulator.

Answer explanation

Repressor is the most correct name.

What is an operon?

• A group of structural genes located next to each other that synthesize proteins.

• A distinct sequence of nucleotides forming part of a chromosome.

• A portion of a DNA molecule that, when translated into amino acids, contains no stop codons.

• A segment of bacterial DNA that can be translocated as a whole between chromosomes.

Note: There could be one, or more than one answer.

Gene transcription would require which of the following? 

• Ribosome

• Promoter

• Sigma factor.

• RNA polymerase

Note: There could be one, or more than one answer.

Protein translation would require which of the following? 

• Promoter region

• tRNA

• mRNA

• Ribosomal subunit

Note: There could be one, or more than one answer.

Which of the following is/are example(s) of quorum sensing? 

• Expression of lac operon

• Biofilm formation

• Bioluminescence

• Toxin production