Question 1

Which of the following best explains why microorganisms are difficult to observe in wet mount preparations?

Accepted Answer

Their rapid movement and transparency make them hard to focus and distinguish from the background.

Question 2

What is the primary advantage of the hanging drop technique over the wet mount technique for observing microbial motility?

Accepted Answer

It prevents evaporation and crushing of organisms, providing a more natural environment for observing motility.

Question 3

Why is petroleum jelly used in the hanging drop technique?

Accepted Answer

To reduce evaporation of the suspended drop of fluid.

Question 4

Which of the following statements about Brownian movement is correct?

Accepted Answer

It results from the random, passive motion of particles due to collisions with water molecules.

Question 5

A student observes dust particles moving randomly in a beam of sunlight. This phenomenon is best explained by:

Accepted Answer

Brownian motion caused by collisions with air molecules.

Question 6

Why should oil immersion lenses NOT be used with the hanging drop technique?

Accepted Answer

Oil can contact and disrupt the hanging drop, causing collapse or contamination.

Question 7

Which of the following is NOT a reason for using alcohol or Gram's iodine in microbiological procedures?

Accepted Answer

To enhance the evaporation rate of the sample.

Question 8

Which of the following best describes a microbiome?

Accepted Answer

A community of microbes, including protists, algae, fungi, and bacteria, that compose the biomass.

Question 9

Which of the following is a key difference between prokaryotes and eukaryotes?

Accepted Answer

Eukaryotes have a true nucleus, while prokaryotes have a nucleoid region.

Question 10

A wet mount is prepared to observe a sample of pond water. Which of the following steps is essential for focusing on living microorganisms?

Accepted Answer

Use high power lens (40x-45x) and increase light intensity.

Question 11

Which of the following is a reason why the drop must be hanging in the hanging drop technique?

Accepted Answer

To allow microorganisms to move freely and prevent evaporation, providing a more accurate observation of their motility.

Question 12

Which of the following is a characteristic of prokaryotic cells?

Accepted Answer

Circular DNA and 70S ribosomes.

Question 13

A patient presents with a bacterial infection. Which of the following is a likely characteristic of the causative agent if it is a prokaryote?

Accepted Answer

It reproduces by binary fission and lacks membrane-bound organelles.

Question 14

Which of the following best explains why Brownian movement is NOT considered true motility?

Accepted Answer

It results from random collisions with water molecules, not from energy-driven movement by the organism.

Question 15

Which of the following is a correct procedure when preparing a wet mount for observing living microbes?

Accepted Answer

Suspend the specimen in a liquid, cover with a coverslip, and observe immediately under the microscope.

Question 16

Which of the following is a reason why the hanging drop technique provides a clearer observation field than the wet mount?

Accepted Answer

It creates a three-dimensional environment, allowing organisms to move in all directions.

Question 17

Which of the following is a plausible reason for using Gram's iodine during a staining procedure?

Accepted Answer

To act as a mordant, fixing the dye inside the cell wall.

Question 18

Which of the following is a limitation of the wet mount technique?

Accepted Answer

It provides limited contrast and may not preserve the sample for long-term observation.

Question 19

Which of the following best describes the main difference in DNA organization between prokaryotes and eukaryotes?

Accepted Answer

Prokaryotes have circular DNA in a nucleoid region, while eukaryotes have linear DNA in a membrane-bound nucleus.

Question 20

Which of the following is a correct application of the wet mount technique in a clinical laboratory?

Accepted Answer

Observing the motility of living bacteria in a urine sample to help diagnose a urinary tract infection.

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