Which instrument is commonly used to determine relative cell density based on the turbidity of a culture?

• A. Microscope
• B. pH meter
• C. Spectrophotometer
• D. Centrifuge

Answer: (C)

Verified step by step guidance

1. Understand that turbidity refers to the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye.
2. Recognize that measuring turbidity is a common method to estimate cell density in a culture, as more cells will scatter more light, increasing the turbidity.
3. Identify that a spectrophotometer is an instrument used to measure the amount of light that a sample absorbs. It can be used to determine the turbidity of a culture by measuring the absorbance or optical density at a specific wavelength.
4. Differentiate between the instruments: A microscope is used for visualizing small objects, a pH meter measures the acidity or alkalinity of a solution, and a centrifuge separates components based on density.
5. Conclude that the spectrophotometer is the correct instrument for determining relative cell density based on turbidity, as it quantifies how much light is absorbed by the suspended particles in the culture.