Question 1

Which part of the microscope is responsible for focusing the specimen by moving the stage up and down in large increments?

Accepted Answer

Coarse adjustment knob

Question 2

If you are using a 10x ocular lens and a 40x objective lens, what is the total magnification?

Accepted Answer

$$10 	imes 40 = 400$$

Question 3

Which tool is most appropriate for transferring bacteria from a broth culture to a solid agar plate using aseptic technique?

Accepted Answer

Inoculating loop

Question 4

What is the main purpose of the streak plate method in microbiology?

Accepted Answer

To isolate pure colonies from a mixed culture

Question 5

A student observes a broth culture that is cloudy throughout. What is the correct term for this growth pattern?

Accepted Answer

Turbid

Question 6

Why is heat-fixing a bacterial smear before staining important?

Accepted Answer

It kills the bacteria and adheres them to the slide

Question 7

Which of the following is a basic (cationic) stain commonly used in simple staining?

Accepted Answer

Crystal violet

Question 8

After performing a Gram stain, you observe purple, spherical cells in clusters. What is the most likely identity of these cells?

Accepted Answer

Gram-positive cocci

Question 9

What is the primary stain used in the acid-fast staining procedure?

Accepted Answer

Carbol fuchsin

Question 10

Which of the following best describes the appearance of endospores after endospore staining?

Accepted Answer

Green endospores, red vegetative cells

Question 11

A microbiologist wants to select for Gram-positive bacteria and differentiate hemolytic activity. Which medium should they use?

Accepted Answer

Columbia CNA with Sheep Blood

Question 12

On Mannitol Salt Agar, which result indicates a bacterium is both halotolerant and a mannitol fermenter?

Accepted Answer

Growth, medium turns yellow

Question 13

Which ingredient in MacConkey Agar makes it selective for Gram-negative bacteria?

Accepted Answer

Crystal violet

Question 14

A student observes green metallic sheen colonies on EMB agar. What does this indicate?

Accepted Answer

Vigorous lactose fermenter (e.g., E. coli)

Question 15

Which of the following best describes the composition of a bacterial capsule?

Accepted Answer

Polysaccharide or polypeptide

Question 16

Which of the following is a correct match between a fungal structure and its function?

Accepted Answer

Sporangiospore – asexual spore of Rhizopus

Question 17

Which protozoan is identified by its characteristic 'trophozoite' form with two nuclei and flagella, and is a common cause of gastrointestinal disease?

Accepted Answer

Giardia lamblia

Question 18

Which helminth is commonly known as the 'Chinese liver fluke'?

Accepted Answer

Clonorchis sinensis

Question 19

Which of the following best describes the charge of the dye used in negative staining?

Accepted Answer

Negative

Question 20

A student observes a slide with both magenta rods and blue cocci after acid-fast staining. What is the correct interpretation?

Accepted Answer

Magenta rods are acid-fast, blue cocci are non-acid-fast

Microbiology Lab Practical Review: Microscopy, Aseptic Technique, Staining, and Microbial Identification

Study Guide - Practice Questions

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