1|Page
MICROBIOLOGY BIOD 171 MODULE 3 EXAM –
PORTAGE LEARNING 2025/2026 ACTUAL EXAM
QUESTIONS AND CORRECT DETAILED ANSWERS
(VERIFIED ANSWERS) ALL ANSWERED {100 Q & A}
ALREADY GRADED A+ | BRAND NEW!
What happens to sample when fixation takes place? - ✔✔✔ Correct
Answer > Sample is killed
What is the 3rd step of gram staining? - ✔✔✔ Correct Answer >
Decolorization agent is added, gram negative bacteria lose dye
What is the 4th step of gram staining? - ✔✔✔ Correct Answer >
Counterstain is added (safranin)
Chemical fixation - ✔✔✔ Correct Answer > Uses paraformaldehyde,
methanol, or ethanol for 1 min
What is differential staining? - ✔✔✔ Correct Answer > At least 2 dyes
are used (multistep process)
What is the purpose of differential staining? - ✔✔✔ Correct Answer >
Show different cells, structures, and chemicals
, 2|Page
What type of microscope is used to observe motility and
behavior? - ✔✔✔ Correct Answer > Brightfield
Stains are ... that break down into positively/negatively charged
ions - ✔✔✔ Correct Answer > Salts
The colored ion in the dye is known as the ... - ✔✔✔ Correct Answer >
Chromophore
Acidic dyes are ... for ... staining - ✔✔✔ Correct Answer > Anionic;
negative staining (stains positively charged structures)
Basic dyes are ... for ... - ✔✔✔ Correct Answer > Cationic; staining
negatively charged structures
Which is the most common stain? - ✔✔✔ Correct Answer > Basic dyes
Simple stain uses how many dyes? - ✔✔✔ Correct Answer > Single
basic dye
What is simple staining used for? - ✔✔✔ Correct Answer > Cell shape,
size, and arrangement
MICROBIOLOGY BIOD 171 MODULE 3 EXAM –
PORTAGE LEARNING 2025/2026 ACTUAL EXAM
QUESTIONS AND CORRECT DETAILED ANSWERS
(VERIFIED ANSWERS) ALL ANSWERED {100 Q & A}
ALREADY GRADED A+ | BRAND NEW!
What happens to sample when fixation takes place? - ✔✔✔ Correct
Answer > Sample is killed
What is the 3rd step of gram staining? - ✔✔✔ Correct Answer >
Decolorization agent is added, gram negative bacteria lose dye
What is the 4th step of gram staining? - ✔✔✔ Correct Answer >
Counterstain is added (safranin)
Chemical fixation - ✔✔✔ Correct Answer > Uses paraformaldehyde,
methanol, or ethanol for 1 min
What is differential staining? - ✔✔✔ Correct Answer > At least 2 dyes
are used (multistep process)
What is the purpose of differential staining? - ✔✔✔ Correct Answer >
Show different cells, structures, and chemicals
, 2|Page
What type of microscope is used to observe motility and
behavior? - ✔✔✔ Correct Answer > Brightfield
Stains are ... that break down into positively/negatively charged
ions - ✔✔✔ Correct Answer > Salts
The colored ion in the dye is known as the ... - ✔✔✔ Correct Answer >
Chromophore
Acidic dyes are ... for ... staining - ✔✔✔ Correct Answer > Anionic;
negative staining (stains positively charged structures)
Basic dyes are ... for ... - ✔✔✔ Correct Answer > Cationic; staining
negatively charged structures
Which is the most common stain? - ✔✔✔ Correct Answer > Basic dyes
Simple stain uses how many dyes? - ✔✔✔ Correct Answer > Single
basic dye
What is simple staining used for? - ✔✔✔ Correct Answer > Cell shape,
size, and arrangement
