$$8,000 \text{ nm} = 8 \text{ µm}$$

$$\text{Total magnification} = 10 \times 40 = 400$$

Question 1

A typical red blood cell is about 8,000 nm in diameter. How many micrometers (µm) is this?

Accepted Answer

$$8,000 	ext{ nm} = 8 	ext{ µm}$$

Question 2

Which of the following best describes the relationship between surface area and volume as a cell increases in size?

Accepted Answer

The surface area increases more slowly than the volume, decreasing the surface area to volume ratio.

Question 3

A compound light microscope has an ocular lens of 10x and an objective lens of 40x. What is the total magnification?

Accepted Answer

$$	ext{Total magnification} = 10 	imes 40 = 400$$

Question 4

Which of the following is NOT observable using a microscope with a resolution of $$0.5 	ext{ µm}$$?

Accepted Answer

Coronavirus (0.1 µm)

Question 5

Why do small cells tend to grow and divide faster than large cells?

Accepted Answer

They have a higher surface area to volume ratio, allowing more efficient nutrient uptake.

Question 6

Which part of the light microscope focuses the light beam and controls the amount of light hitting the specimen?

Accepted Answer

Condenser

Question 7

Which of the following statements about electron microscopes is TRUE?

Accepted Answer

They use beams of electrons, which have a shorter wavelength than light, resulting in higher resolution.

Question 8

Which type of microscope would be best for viewing the external surface of a pollen grain in three dimensions?

Accepted Answer

Scanning Electron Microscope (SEM)

Question 9

Which of the following best describes the purpose of using immersion oil with a 100x objective lens?

Accepted Answer

It increases the resolution by reducing light refraction.

Question 10

Which of the following stains is used to identify bacteria with waxy cell walls, such as Mycobacterium tuberculosis?

Accepted Answer

Acid-fast stain

Question 11

During the Gram staining procedure, what color will Gram-negative bacteria appear after the application of safranin?

Accepted Answer

Pink/red

Question 12

Which of the following statements about simple staining is correct?

Accepted Answer

A basic dye is positively charged and stains the inside of a cell, while an acidic dye is negatively charged and stains the background.

Question 13

Which of the following is a differential stain that divides bacteria into two groups based on cell wall structure?

Accepted Answer

Gram stain

Question 14

What is the main advantage of using a phase-contrast microscope over a bright-field microscope?

Accepted Answer

It increases contrast in unstained, living cells.

Question 15

Which of the following best describes the function of a mordant in staining procedures?

Accepted Answer

It helps fix the dye to the specimen or increases the size of a structure.

Question 16

Which of the following is a correct match between a special stain and its target structure?

Accepted Answer

Flagella stain: stains the flagella of bacteria

Question 17

A student observes a bacterial sample under a microscope after performing a negative stain. What will be the appearance of the cells?

Accepted Answer

Cells appear colorless against a dark background.

Question 18

Which of the following best explains why electron microscopes can resolve much smaller structures than light microscopes?

Accepted Answer

Electrons have a much shorter wavelength than visible light.

Question 19

Which of the following is the correct order of steps in the Gram staining procedure?

Accepted Answer

Crystal violet, iodine, alcohol/acetone, safranin

Question 20

Which of the following best describes the main difference between Transmission Electron Microscopes (TEM) and Scanning Electron Microscopes (SEM)?

Accepted Answer

TEM provides 2D images of internal structures, while SEM provides 3D images of surfaces.

Visualization of Bacteria: Microscopy and Staining Techniques

Study Guide - Practice Questions