Lab Final Review - Week #1

Question 1

What is a pure culture?

Answer 1

A culture containing a single, unadulterated species of cells

Question 2

What is culture medium?

Answer 2

It can be liquid, solid, or semisolid and it is made up of soluble low-molecular-weight substances derived from the enzymatic degradation of complex nutrients

Question 3

What is agar?

Answer 3

A solidifying agent; it is an extract of seaweed and it is a complex carbohydrate composed mainly of galactose. It has no nutritional value, it solidifies at 40 C and liquefies at 100

Question 4

What is the primary purpose of agar slants?

Answer 4

For maintaining pure cultures

Question 5

What is the primary purpose of agar deep tubes?

Answer 5

To study the gaseous requirements of microorganisms

Question 6

What is the primary purpose of agar plates?

Answer 6

They provide a large surface area for the isolation and study of microorganisms

Question 7

Why are petri dishes incubated in an inverted position after incubation?

Answer 7

To prevent condensation, which forms on the cover during solidification, from dropping sown onto the surface of the hardened agar.

Question 8

What is subculturing?

Answer 8

It is the transfer of microorganisms from stock cultures to various media for maintenance and study

Question 9

What types of metals are wire loops and needles made from?

Answer 9

Inert metals such as nichrome and platinum

Question 10

What is the estimated amount of normal (resident) flora on an adult?

Answer 10

one trillion bacteria

Question 11

What are benefits and risks of residential flora?

Answer 11

It creates a symbiotic relationship with your skin which is vital to your health. Problems can occur however if the immune system is compromised or if the microorganisms gain entrance into the body

Question 12

What is transient flora?

Answer 12

Microorganisms that are less permanent and can be removed with good hand washing techniques

Question 13

Why is resident flora difficult to remove?

Answer 13

Because it can be found in the hair follicles which means it is covered by hair, oil, and dead skin cells

Question 14

How can resident flora be removed?

Answer 14

Surgical scrubbing

Question 15

Who is responsible for introducing surgical hand washing into the medical practice?

Answer 15

Hungarian physician Ignatz Semmelweis in the mid-nineteenth century

Question 16

What is puerperal fever?

Answer 16

It is childbirth fever

Question 17

Once flamed, how long do you wait before you insert the sterilized loop/needle into an inoculum?

Answer 17

10-20 seconds

Question 18

Would you use a loop or a needle in a slant-to-broth transfer?

Answer 18

either, just ensure that you lightly shake it in order to dislodge the microorganisms into the broth

Question 19

Would you use a loop or a needle in a broth-to-slant?

Answer 19

A loop, and you would zigzag it onto the slant

Question 20

Would you use a loop or a needle in a slant-to-agar deep transfer? This transfer is also called what?

Answer 20

A needle; also called a stab inoculation

Question 21

Why is isolation of pure cultures important?

Answer 21

It allows us to study their cultural, morphological, and biochemical properties

Question 22

What are discrete colonies?

Answer 22

Individual, macroscopically visible masses of microbial growth on a solid medium; each representing the multiplication of a single organism

Question 23

What are the 3 techniques commonly used for the isolation of discrete cultures?

Answer 23

1. streak-plate
2. spread-plate
3. pour-plate

Question 24

How does the pour-plate technique allow for the isolation of discrete cultures?

Answer 24

The mixed culture is serial diluted and the added to molten agar.

Question 25

What are cultural characteristics?

Answer 25

Differences in the macroscopic appearance of the growth of microorganisms, these are used as a basis for separating microorganisms into taxonomic groups

Question 26

How are cultural characteristics determined?

Answer 26

By culturing the organisms and observing their growth patterns.

Question 27

What 5 cultural characteristics can be observed on a nutrient agar slant?

Answer 27

1. abundance of growth
2. pigmentation
3. optical characteristics
4. form
5. consistency

Question 28

What 5 cultural characteristcs can be observed on a nutrient agar plate?

Answer 28

1. size
2. pigmentation
3. form
4. margin
5. elevation

Question 29

What 4 cultural characteristics can be observed in a nutrient broth tube?

Answer 29

1. uniform fine turbidity
2. flocculent
3. pellicle
4. sediment

Question 30

How are inoculating loops sterilized?

Answer 30

incineration

Question 31

How many loopfuls of broth culture are used to inoculate a streak plate?

Answer 31

one

Question 32

Identify two properties of agar that make it useful for cultivating microorganisms?

Answer 32

1. solidifying agent

2. transparency