Question 1

Which of the following statements best describes the main function of bacterial endospores?

Accepted Answer

They allow bacteria to survive harsh environmental conditions such as heat, drying, and radiation.

Question 2

Which two genera are known for their ability to form endospores?

Accepted Answer

Bacillus and Clostridium

Question 3

What is the metabolically active, growing form of a bacterium that forms an endospore called?

Accepted Answer

Vegetative cell

Question 4

During the endospore staining procedure, why is heat applied while staining with malachite green?

Accepted Answer

To allow malachite green to penetrate the resistant spore coat

Question 5

After completing the endospore staining procedure, what color will the endospores and vegetative cells appear under the microscope?

Accepted Answer

Endospores: green, Vegetative cells: red

Question 6

Which of the following best describes the role of water in the endospore staining procedure?

Accepted Answer

It is used as a decolorizing agent to remove malachite green from vegetative cells.

Question 7

Which arrangement of flagella is characterized by a single flagellum at each pole of the bacterium?

Accepted Answer

Amphitrichous

Question 8

What is the main function of the basal body in a bacterial flagellum?

Accepted Answer

It anchors the flagellum to the cell wall and cytoplasmic membrane and acts as a rotary motor.

Question 9

A student prepares a motility test medium with 3% agar instead of 0.3%. What is the most likely outcome?

Accepted Answer

Motility will not be detected because the medium is too solid for bacteria to move.

Question 10

Which of the following best describes chemotaxis in bacteria?

Accepted Answer

Movement in response to chemical gradients

Question 11

What is the purpose of using a semi-solid motility test medium with 0.3% agar?

Accepted Answer

To allow motile bacteria to move while still forming a soft gel

Question 12

Which of the following is NOT a correct method for detecting bacterial motility?

Accepted Answer

Gram staining

Question 13

What is the behavior called when motile bacteria alternate between swimming and tumbling, resulting in overall movement toward an attractant?

Accepted Answer

Biased random walk

Question 14

Which of the following best describes axial filaments?

Accepted Answer

They are endoflagella located between the cell wall and outer membrane of spirochetes.

Question 15

A student observes a stained slide under oil immersion and sees green ovals inside pink rods. What is the best interpretation?

Accepted Answer

The green ovals are endospores and the pink rods are vegetative cells.

Question 16

Which stain is used as the primary stain in the endospore staining procedure?

Accepted Answer

Malachite green

Question 17

What is the correct sequence of steps in the endospore staining procedure?

Accepted Answer

Apply malachite green with heat, rinse with water, apply safranin

Question 18

Which of the following best explains why flagella are difficult to see with a standard light microscope?

Accepted Answer

Flagella are below the resolution limit of the light microscope.

Question 19

When using motility test medium, how can you distinguish between motile and non-motile bacteria?

Accepted Answer

Motile bacteria grow throughout the tube; non-motile bacteria grow only along the stab line.

Question 20

What happens to a motile bacterium when its flagella switch from counterclockwise to clockwise rotation?

Accepted Answer

The cell tumbles and changes direction.

Endospore Staining and Bacterial Motility: Lab Study Guide

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