MG&G Test 5 Baylor questions with
complete solutions graded A+
2025/2026
3 Divisions of Life - correct answer ✔✔Archaea, Bacteria, Eukarya
% of Human Gut microbiota that is Bacteria - correct answer ✔✔98%
How we Identify Bacteria? - correct answer ✔✔Dependent upon molecular markers (usually on
16S rRna gene)
Where is the 16S rRNA gene found? - correct answer ✔✔In the ribosome
Does the 16S rRNA gene have one or many segements? - correct answer ✔✔Many variable
segments
What does each sequence variant correspond to? - correct answer ✔✔A different Bacterial
genus
Where are primers placed and what happens after they are placed? - correct answer
✔✔Primers are placed on the conserved segment flanking the variable segment, after
placement PCR is used to amplify the region to then be sequenced.
What does the # of hits represent? - correct answer ✔✔The proportion of the genus in the
population for each variant
Why don't most Bacteria like being studied? - correct answer ✔✔They cannot be cultured
, How many phyla of bacteria are known via 16S rRNA metagenomics? - correct answer ✔✔142
How many phyla of bacteria have been cultured? - correct answer ✔✔39
4 phyla of bacteria which predominate human gut - correct answer ✔✔Proteobacteria,
Bacteroidetes, Actinobacteria, Firmicutes
What is the Gram stain? - correct answer ✔✔It is a test to determine if a bacteria is gram
positive or gram negative.
Gram + - correct answer ✔✔thick peptidoglycan wall w/ membrane within that
Gram - - correct answer ✔✔Very thin peptidoglycan wall, either side of that has a membrane
(lipid bilayer)
How to Gram Stain: - correct answer ✔✔1.) add crystal violet-iodine, and purple crystals for in
all cells
2.) wash with alcohol (+ will dehydrate peptidoglycan, and CV-I crystals won't leave. - will
dissolve outer membrane (LPS) and leaves holes in peptidoglycan, so CV-I washes out)
3.) Add safranin. Gram+ will not take it up, remaining purple. Gram- stain pink
Phylum: Proteobacteria - correct answer ✔✔Gamma Class, Beta Class, Alpha Class, Epsilon Class
Gamma Class - correct answer ✔✔Vibrio
Yersinia
Salmonella, Shigella, Escherichia
Pseudomonas
complete solutions graded A+
2025/2026
3 Divisions of Life - correct answer ✔✔Archaea, Bacteria, Eukarya
% of Human Gut microbiota that is Bacteria - correct answer ✔✔98%
How we Identify Bacteria? - correct answer ✔✔Dependent upon molecular markers (usually on
16S rRna gene)
Where is the 16S rRNA gene found? - correct answer ✔✔In the ribosome
Does the 16S rRNA gene have one or many segements? - correct answer ✔✔Many variable
segments
What does each sequence variant correspond to? - correct answer ✔✔A different Bacterial
genus
Where are primers placed and what happens after they are placed? - correct answer
✔✔Primers are placed on the conserved segment flanking the variable segment, after
placement PCR is used to amplify the region to then be sequenced.
What does the # of hits represent? - correct answer ✔✔The proportion of the genus in the
population for each variant
Why don't most Bacteria like being studied? - correct answer ✔✔They cannot be cultured
, How many phyla of bacteria are known via 16S rRNA metagenomics? - correct answer ✔✔142
How many phyla of bacteria have been cultured? - correct answer ✔✔39
4 phyla of bacteria which predominate human gut - correct answer ✔✔Proteobacteria,
Bacteroidetes, Actinobacteria, Firmicutes
What is the Gram stain? - correct answer ✔✔It is a test to determine if a bacteria is gram
positive or gram negative.
Gram + - correct answer ✔✔thick peptidoglycan wall w/ membrane within that
Gram - - correct answer ✔✔Very thin peptidoglycan wall, either side of that has a membrane
(lipid bilayer)
How to Gram Stain: - correct answer ✔✔1.) add crystal violet-iodine, and purple crystals for in
all cells
2.) wash with alcohol (+ will dehydrate peptidoglycan, and CV-I crystals won't leave. - will
dissolve outer membrane (LPS) and leaves holes in peptidoglycan, so CV-I washes out)
3.) Add safranin. Gram+ will not take it up, remaining purple. Gram- stain pink
Phylum: Proteobacteria - correct answer ✔✔Gamma Class, Beta Class, Alpha Class, Epsilon Class
Gamma Class - correct answer ✔✔Vibrio
Yersinia
Salmonella, Shigella, Escherichia
Pseudomonas
