Basics - T01

Question 1

Gram-ve bacteria are _______ in Gram stain.

Answer 1

Red

Question 2

Gram+ve bacteria are _________ in Gram stain.

Answer 2

Blue

Question 3

____________organisms require blood or chocolate agar to grow.

Answer 3

Fastidious

Question 4

MacConkey agar helps to distinguish?

Answer 4

Lactose-fermenting organisms (pink) from non-lactose fermenting organisms (no change)

Question 5

Blood agar can differentiate certain organisms by their ability to produce different types of?

Answer 5

Hemolysis

Question 6

Some media will inhibit the growth of most organisms other than that for which the media are devised.

e. g.
1. Tellurite media is for?
2. Mannitol salt agar is for?

Answer 6

1. Diphtheria bacillus

2. Staphylococcus aureus

Question 7

How can we identify bacteria by 5 steps? (3 steps is sufficient)

Answer 7

1. Gram’s stain morphology
2. Colonial morphorlogy
3. Biochemical properties/ Proteinomics
4. Serological properties
5. Genotypic properties

Question 8

Exam question: Describe how to perform a Gram’s stain. (5)

Answer 8

Apply a smear of bacteria on slide

1. Stain cells with crystal violet
2. Add iodine to form intracellular stain complex
3. Decolorize by using 95% alcohol
4. Counterstain with safranin O