2025-2026 SERIES
MICROBIOLOGY LAB PRACTICAL 1 (PEARSON
EDUCATION EDITION) COMPLETE QUESTIONS AND
CORRECT ANSWERS | GRADED AND THE LATEST
SERIES
What bacterial shape is observed?
Ans: Bacillus
What bacterial shape is observed?
Ans: Coccus
What bacterial shape is observed?
Ans: Spiral/spirochete
How does increase in magnification affect field of vision?
Ans: It makes it smaller
How does increased magnification affect depth of field?
Ans: Depth of field becomes larger
Why is it desirable that microscope objectives be parfocal?
Ans: So each objective does not require further focusing
Which objective focuses the closest to the slide when it is in focus?
, 2025-2026 SERIES
Ans: The dry-oil / oil lens objective
Which controls on the microscope affect the amount of light reaching the ocular
lens?
Ans: The rheostat and the diaphragm
Assume the diameter of the field of vision in your microscope is 2mm under low
power. If one Bacillus cell measures 2 um, how many Bacillus cells could fit end-
to-end across the field?
Ans: 2,000 Bacillus cells at 2mm low power
How many 10 um yeast cells could fit across the field?
Ans: 200 yeast cells at 2mm low power
What are the advantages of the low-power objective over the oil immersion /
dry-oil objective for viewing fungi or algae?
Ans: The organism can be viewed in its entirety, rather than being limited to only
one area and one plane at a time.
What would occur if water were accidentally used in place of oil immersion /
dry oil?
Ans: It would act as another lens and distort the focusing power, or distort the
image being viewed.
, 2025-2026 SERIES
Assume you are looking for microorganisms in a tissue sample from a lung
biopsy. The microbes become apparent when you switch to 1000X. What type
of microbe is most likely?
Ans: Bacteria (because it is a prokaryote, and they are much smaller, and
therefore much more difficult to see at lower powers under the microscope)
What is Brownian movement?
Ans: Movement caused by the molecules in the liquid striking an object and
causing that object to bounce.
What is true motility?
Ans: Motile microorganisms are able to move from one position to another of
their own accord.
How do you distinguish true motility from Brownian movement or motion of the
fluid?
Ans: True motility has purposeful movement. Brownian movement consists mostly
of shaking.
What, if any, practical value do the wet mount and hanging drop techniques
have?
Ans: Allows the viewing of activity of living cells, how they move, and interact
with their environment.
Why are microorganisms hard to see in wet preparations?
MICROBIOLOGY LAB PRACTICAL 1 (PEARSON
EDUCATION EDITION) COMPLETE QUESTIONS AND
CORRECT ANSWERS | GRADED AND THE LATEST
SERIES
What bacterial shape is observed?
Ans: Bacillus
What bacterial shape is observed?
Ans: Coccus
What bacterial shape is observed?
Ans: Spiral/spirochete
How does increase in magnification affect field of vision?
Ans: It makes it smaller
How does increased magnification affect depth of field?
Ans: Depth of field becomes larger
Why is it desirable that microscope objectives be parfocal?
Ans: So each objective does not require further focusing
Which objective focuses the closest to the slide when it is in focus?
, 2025-2026 SERIES
Ans: The dry-oil / oil lens objective
Which controls on the microscope affect the amount of light reaching the ocular
lens?
Ans: The rheostat and the diaphragm
Assume the diameter of the field of vision in your microscope is 2mm under low
power. If one Bacillus cell measures 2 um, how many Bacillus cells could fit end-
to-end across the field?
Ans: 2,000 Bacillus cells at 2mm low power
How many 10 um yeast cells could fit across the field?
Ans: 200 yeast cells at 2mm low power
What are the advantages of the low-power objective over the oil immersion /
dry-oil objective for viewing fungi or algae?
Ans: The organism can be viewed in its entirety, rather than being limited to only
one area and one plane at a time.
What would occur if water were accidentally used in place of oil immersion /
dry oil?
Ans: It would act as another lens and distort the focusing power, or distort the
image being viewed.
, 2025-2026 SERIES
Assume you are looking for microorganisms in a tissue sample from a lung
biopsy. The microbes become apparent when you switch to 1000X. What type
of microbe is most likely?
Ans: Bacteria (because it is a prokaryote, and they are much smaller, and
therefore much more difficult to see at lower powers under the microscope)
What is Brownian movement?
Ans: Movement caused by the molecules in the liquid striking an object and
causing that object to bounce.
What is true motility?
Ans: Motile microorganisms are able to move from one position to another of
their own accord.
How do you distinguish true motility from Brownian movement or motion of the
fluid?
Ans: True motility has purposeful movement. Brownian movement consists mostly
of shaking.
What, if any, practical value do the wet mount and hanging drop techniques
have?
Ans: Allows the viewing of activity of living cells, how they move, and interact
with their environment.
Why are microorganisms hard to see in wet preparations?
