BIOS 242 Lab Practical Exam
QUESTIONS AND VERIFIED
CORRECT ANSWERS LATEST
2026-2027
100x - CORRECT ANSWER-when do you use oil immersion?
parfocal - CORRECT ANSWER-means that you can change the focus (objective lens) of a
microscope without having to focus it every time
light under the stage or the iris diaphragm - CORRECT ANSWER-how do you change the light
reaching the ocular lens?
iris diaphragm - CORRECT ANSWER-controls the amount of light that is passing through (the
larger the hole the more light)
protozoa - CORRECT ANSWER-single celled
no because eukaryotes are so big you do not need to magnify them beyond 40x - CORRECT
ANSWER-do you need oil immersion for eukaryotes?
b. cereus - CORRECT ANSWER-gram positive rod
, s. cerveisiae - CORRECT ANSWER-responsible for making beer
to attach the bacteria to the slide so it doesn't wash off during the staining process - CORRECT
ANSWER-why do you heat fix a specimen?
the water helps to improve clarity of the organism also if it was a live organism you would be
able to see it move - CORRECT ANSWER-why do you use a wet mount?
allows us to see size, morphology, and arrangement - CORRECT ANSWER-why do we use simple
staining techniques?
it makes sure that the bacteria is dry so when you heat it it doesn't change the shape of the
bacteria - CORRECT ANSWER-why do you air dry your slide?
s. epidermidis - CORRECT ANSWER-gram positive bacteria (cocci)
gram positive - CORRECT ANSWER-purple
gram negative - CORRECT ANSWER-pink
gram positive - CORRECT ANSWER-thick layer of peptidoglycn
gram negative - CORRECT ANSWER-thin layer of peptidoglycan with an outer membrane that
contains lipid a
e. coli - CORRECT ANSWER-gram negative rod shaped
mixed culture - CORRECT ANSWER-a mixed culture of gram positive and gram negative
QUESTIONS AND VERIFIED
CORRECT ANSWERS LATEST
2026-2027
100x - CORRECT ANSWER-when do you use oil immersion?
parfocal - CORRECT ANSWER-means that you can change the focus (objective lens) of a
microscope without having to focus it every time
light under the stage or the iris diaphragm - CORRECT ANSWER-how do you change the light
reaching the ocular lens?
iris diaphragm - CORRECT ANSWER-controls the amount of light that is passing through (the
larger the hole the more light)
protozoa - CORRECT ANSWER-single celled
no because eukaryotes are so big you do not need to magnify them beyond 40x - CORRECT
ANSWER-do you need oil immersion for eukaryotes?
b. cereus - CORRECT ANSWER-gram positive rod
, s. cerveisiae - CORRECT ANSWER-responsible for making beer
to attach the bacteria to the slide so it doesn't wash off during the staining process - CORRECT
ANSWER-why do you heat fix a specimen?
the water helps to improve clarity of the organism also if it was a live organism you would be
able to see it move - CORRECT ANSWER-why do you use a wet mount?
allows us to see size, morphology, and arrangement - CORRECT ANSWER-why do we use simple
staining techniques?
it makes sure that the bacteria is dry so when you heat it it doesn't change the shape of the
bacteria - CORRECT ANSWER-why do you air dry your slide?
s. epidermidis - CORRECT ANSWER-gram positive bacteria (cocci)
gram positive - CORRECT ANSWER-purple
gram negative - CORRECT ANSWER-pink
gram positive - CORRECT ANSWER-thick layer of peptidoglycn
gram negative - CORRECT ANSWER-thin layer of peptidoglycan with an outer membrane that
contains lipid a
e. coli - CORRECT ANSWER-gram negative rod shaped
mixed culture - CORRECT ANSWER-a mixed culture of gram positive and gram negative
