Question

What is the reagent used in the phenylalanine deamination test?

	A.	Ammonia
	B.	Ferric chloride
	C.	Phenylalanine
	D.	Kovac's reagent

Partial lysis of the red blood cells surrounding a bacterial colony indicate that the colony is ______.

	A.	beta hemolytic
	B.	alpha hemolytic
	C.	gamma hemolytic
	D.	nonhemolytic

If you were to observe the cells under the microscope after the addition of the Gram’s iodine, what would their color be?

	A.	All cells would be colorless.
	B.	All cells would be brown.
	C.	All cells would be purple.
	D.	All cells would be red/pink

What do streptococci and staphylococci have in common?

	A.	Coagulase-positive
	B.	Gram-positive
	C.	Catalase-positive
	D.	Gram-negative

What would colonies of Salmonella or Shigella look like on MacConkey agar?

	A.	Smooth colorless colonies
	B.	Purple colonies
	C.	Clear colonies with a black center
	D.	Pink colonies with a black center

Answer 1

1. Option B is the correct answer.

In this test ferric chloride is added to the phenylalanine which results in the development of light to dark green colour after 1 to 5 minutes of reagent addition.

2. Option B is the correct answer.

Partial hemolysis indicates alpha hemolysis while complete analysis indicates beta hemolysis.

3. Option B is the correct answer.

Grams iodine will produce brown colour.

4. Option B is the correct answer.

Both are gram positive bacteria.

5. Option A is the correct answer.

Lactose fermenting strains grow as red or pink while lactose nonfermenting bacteria like shegella and salmonella are colourless and transparent.