7/21/25, 8:48
AM
MBIO 1220: FINAL EXAM QUESTIONS AND
ANSWERS WITH COMPLETE SOLUTIONS
VERIFIED GRADED A++ 2025/2026
Terms in this set (959)
Two types of light microscope (compound) OR
microscopes electron microscopes (transmission,
scanning, scanning tunneling)
compound light Any microscope that uses visible light to
microscope observe specimens
compound light objective 100X (by specimen) and ocular
microscope lenses 10x (eye piece)
total magnification objective lense mag times ocular lenses
mag = 1000
what is the net negative
charge of the
outer surface of
the bacteria
positive stains adhere to negatively charged
bacterium, bacteria turns colour of
stain, background is clear, ex:
1/
16
,7/21/25, 8:48
AM
Crystal Violet
negative stains repelled negatively charged
bacterium, bacteria will appear
clear, background will be coloured,
ex: Nigrosin
simple stains a single coloured basic dye is used,
basic dyes have positively charged
colour ion therefore binds to
organism staining it that colour,
sometimes uses mordant
used to differentiate between bacterias,
differential stains important for diagnostics, exploits
differences in cell wall structure and
composition, ex: the Gram stain, acid
fast stain, endospore, capsule stain
the Gram stain determines whether a bacterium is Gram
positive or Gram negative
acid fast stain carbolfuchsin used to stain
Mycobacterium (waxy/hydrophobic)
pink, methylene blue stains all non-
acid fast cells (negative)
why will because they're waxy (mycolic acid)
Mycobacterium not - they are gram positive but mycolic
Gram stain? acid is outside of this
2/
16
, 7/21/25, 8:48
AM
peptidoglycan
capsule stain 2 stains - positive stain will stain cell
membrane and negative stain always
sticks to background, white halo left
is the positively charged halo
around cell
3/
16
AM
MBIO 1220: FINAL EXAM QUESTIONS AND
ANSWERS WITH COMPLETE SOLUTIONS
VERIFIED GRADED A++ 2025/2026
Terms in this set (959)
Two types of light microscope (compound) OR
microscopes electron microscopes (transmission,
scanning, scanning tunneling)
compound light Any microscope that uses visible light to
microscope observe specimens
compound light objective 100X (by specimen) and ocular
microscope lenses 10x (eye piece)
total magnification objective lense mag times ocular lenses
mag = 1000
what is the net negative
charge of the
outer surface of
the bacteria
positive stains adhere to negatively charged
bacterium, bacteria turns colour of
stain, background is clear, ex:
1/
16
,7/21/25, 8:48
AM
Crystal Violet
negative stains repelled negatively charged
bacterium, bacteria will appear
clear, background will be coloured,
ex: Nigrosin
simple stains a single coloured basic dye is used,
basic dyes have positively charged
colour ion therefore binds to
organism staining it that colour,
sometimes uses mordant
used to differentiate between bacterias,
differential stains important for diagnostics, exploits
differences in cell wall structure and
composition, ex: the Gram stain, acid
fast stain, endospore, capsule stain
the Gram stain determines whether a bacterium is Gram
positive or Gram negative
acid fast stain carbolfuchsin used to stain
Mycobacterium (waxy/hydrophobic)
pink, methylene blue stains all non-
acid fast cells (negative)
why will because they're waxy (mycolic acid)
Mycobacterium not - they are gram positive but mycolic
Gram stain? acid is outside of this
2/
16
, 7/21/25, 8:48
AM
peptidoglycan
capsule stain 2 stains - positive stain will stain cell
membrane and negative stain always
sticks to background, white halo left
is the positively charged halo
around cell
3/
16
