One way to detect bacterial motility in the laboratory is to stab cells into which type of medium?

• A. Selective agar medium
• B. Blood agar plate
• C. Semi-solid agar medium
• D. Nutrient broth

Answer: (C)

Verified step by step guidance

1. Understand the concept of bacterial motility: Motility refers to the ability of bacteria to move by themselves, often using structures like flagella.
2. Recognize that to test for motility, the medium must allow movement but also provide some resistance to observe this movement clearly.
3. Identify that selective agar medium is designed to inhibit or promote growth of certain bacteria, not specifically for motility testing.
4. Know that blood agar plates are used to detect hemolysis (breakdown of red blood cells), not motility.
5. Conclude that a semi-solid agar medium is used because its lower agar concentration (usually around 0.4%) allows motile bacteria to move through the medium, making it possible to detect motility by observing the spread of growth away from the stab line.