Respirometer: An Instrument to Measure Respiration Rate and Respiratory Quotient

Respirometer is an instrument used to measure the rate of respiration and the respiratory quotient. It provides valuable information about cellular respiration and the metabolic activity of organisms. Let's explore each of these measurements in detail.

1. Rate of Respiration:
The rate of respiration refers to the amount of oxygen consumed or carbon dioxide produced per unit of time. Respirometers are designed to measure this rate by monitoring the changes in gas volume or gas concentration.

- Gas Volume Measurement: In a respirometer, an organism is placed in a sealed chamber along with a substance that absorbs carbon dioxide, such as soda lime. As the organism undergoes respiration, it consumes oxygen and produces carbon dioxide, leading to a decrease in gas volume within the chamber. This change in volume is measured using a gas syringe or a manometer, which provides an indication of the rate of respiration.

- Gas Concentration Measurement: Another method involves measuring the changes in gas concentration using sensors or probes. These sensors detect the amount of oxygen consumed or carbon dioxide produced by the organism, providing a real-time measurement of the respiration rate.

2. Respiratory Quotient:
The respiratory quotient (RQ) is the ratio of the volume of carbon dioxide produced to the volume of oxygen consumed during respiration. It provides information about the type of respiratory substrate being utilized by an organism.

RQ = Volume of CO2 produced / Volume of O2 consumed

Different respiratory substrates, such as carbohydrates, fats, and proteins, have varying RQ values. For example, carbohydrates have an RQ of 1, fats have an RQ of 0.7, and proteins have an RQ ranging from 0.8 to 1.0. By measuring the RQ, respirometers help determine the primary substrate being metabolized by an organism.

Conclusion:
In conclusion, a respirometer is an instrument used to measure the rate of respiration and the respiratory quotient. It provides insights into the metabolic activity of organisms, helping researchers and scientists understand their energy utilization and respiratory substrates. By employing gas volume or concentration measurements, respirometers offer valuable data for various fields such as physiology, ecology, and biochemistry. Therefore, the correct answer to the given question is option 'C' - Both of these.