Labs - Appendices

Question 1

Define pure culture

Answer 1

Contains only 1 kind of MCO

Question 2

Define a defined medium

Answer 2

Exact chemical composition of medium is known

Question 3

Define and undefined medium and possible supplements

Answer 3

• Exact chemical composition is unknown
• Yeast extract for range of vitamins
• Acid hydrolysed yeast nucleic acid for nucleic acids

Question 4

Define a selective medium and how it can be made

Answer 4

• Permits the growth of desired organims and prevents/inhibits growth of others
• Adding compound to inhibit undesired
• Removing compound required by undesired

Question 5

Define a differential medium

Answer 5

Supports the growth of many but has components to produce visual changes to distinguish them

Question 6

Define a selective-differential medium

Answer 6

Selects for a small group of organisms and differentiates them

Question 7

What concentration is used for solid vs semi-solid agar?

Answer 7

Solid = 1.5-2.5%
Semi-solid = <1%

Question 8

What are peptone yeast extract agar (PYEA) plates used for?

Answer 8

Basic medium for cultivating organisms from environmental sources

Question 9

What are blood agar (BA) plates used for?

Answer 9

Enriched medium for isolating fastidious organisms using horse blood as source of nutrients and indicating types of haemolysis

Question 10

What is the purpose of a wet mount?

Answer 10

Determine specific activities of MCOs including motility and reactions

Question 11

What is the purpose of a hanging drop microscopic observation technique?

Answer 11

Same as wet mount but less distortion from coverslip weight and a deeper field of focus into the dro

Question 12

When is the streak plate method used?

Answer 12

Direct plating of material with large numbers of bacteria to dilute the sample with each step

Question 13

What is the aim of swab inoculation?

Answer 13

Cover entire surface of agar plate with inoculum to create microbial lawn without gaps