Lesson 11

Question 1

Contamination can be avoided by

Answer 1

(1) regular checking of culture
(2)
avoidance of use of antibiotics for at least a part of incubation period to reveal cryptic
contaminations,
(3) always use sterile reagents and materials,
(4) exclusive use of
media, materials for different cell lines,
(5) strict observation of standard sterile
technique at all times.

Question 2

Elements of aseptic environment

Answer 2

Quiet area
Work surface
Personal hygiene
Reagent and media
Culture

Question 3

should be avoided to avoid mycoplasmal
contamination and prevent hazard to the operator.

Answer 3

Mouth pipetting

Question 4

should be avoided as much as possible to prevent generation of a bridge of
liquid between the outside of the bottle and the inside, which may permit
contamination to enter the bottle.

Answer 4

Pouring

Question 5

Sterile Handling

Answer 5

Swabbing
Capping
Flamming
Handling bottles and flasks
Pipetting
Pouring

Question 6

An equipment that protect work surface from dust and contamination by a
constant, stable flow of filtered air passing over the work surface.

Answer 6

Safety cabinet

Question 7

, where air blows from the side facing you, parallel to the work surface, and
not circulated

Answer 7

horizontal

Question 8

where air blows down from the top of the hood onto the
work surface and is drawn through the work surface and either recirculated or vented.

Answer 8

Vertical

Question 9

are used to sterilize the air and exposed work surfaces in laminar
flow hoods between uses.

Answer 9

Ultraviolet lights

Question 10

are a major source of contamination. I

Answer 10

Humidified incubators

Question 11

at the bottom of the incubator can
be supplemented with a fungicide to retard fungal growth

Answer 11

humidifier tray