Question

Respirometer is an instrument used to measure (a) rate of respiration (b) respiratory quotient (c) both of these (d) none of these.

Short answer

A respirometer is used to measure both the rate of respiration and the respiratory quotient.

Step-by-step solution

Identify the Function of a Respirometer

A respirometer is an instrument that measures the amount of oxygen consumed by a living organism over a period of time. This allows scientists to determine the rate of respiration by measuring oxygen uptake.

Understanding Respiratory Quotient (RQ)

Respiratory Quotient is a dimensionless number used in calculations of basal metabolic rate (BMR) when estimated from carbon dioxide production. It is calculated from the ratio of the volume of carbon dioxide produced to the volume of oxygen consumed while food is being metabolized.

Determine What a Respirometer Measures

Since a respirometer can be used to measure the amount of oxygen consumed (thereby assessing the rate of respiration) and can also be used to determine the respiratory quotient by measuring both the volume of oxygen consumed and carbon dioxide produced, it can measure both the rate of respiration and respiratory quotient.

Key concepts

Rate of Respiration

The rate of respiration is a vital parameter for understanding the metabolic activity of an organism. It can be described as the frequency at which an organism takes in oxygen and expels carbon dioxide. In biological studies, knowing the rate at which these processes occur is crucial for determining an organism's energy requirements and overall health. A respirometer, a device that facilitates such measurements, gauges the amount of oxygen an organism consumes within a specific timeframe. This rate is often measured in a closed system where changes in the volume or pressure of oxygen can be precisely monitored. By observing how much oxygen is used, biologists can infer the organism's metabolic rate, making the respirometer an indispensable tool in physiology experiments.

Respiratory Quotient

The respiratory quotient (RQ) is an important physiological metric that reflects the type of substrate an organism is using to produce energy. Calculated as the ratio of carbon dioxide produced (CO₂) to oxygen consumed (O₂), RQ values typically range from 0.7 to 1.0. Carbohydrates, fats, and proteins have different RQ values; for instance, an RQ close to 1.0 indicates a carbohydrate-based metabolism, whereas values closer to 0.7 suggest fat is the primary energy source. Through the data obtained from a respirometer, researchers can calculate the RQ and make inferences about which energy stores are being mobilized, which is pivotal for studies in nutrition, exercise physiology, and metabolic disorders.

Basal Metabolic Rate

Basal Metabolic Rate (BMR) is the amount of energy expressed in calories that an organism needs to maintain vital functions at rest – these include breathing, circulating blood, and basic brain functions. It is the minimum rate of energy expenditure per unit time by endothermic animals at rest. Various factors, such as age, sex, body size, and temperature, influence BMR. The respiratory quotient is instrumental in estimating BMR since it provides information about the predominant fuel source the body is utilizing. A respirometer can indirectly contribute to determining BMR by measuring the volume of oxygen consumption and carbon dioxide production, thereby helping in understanding how metabolic rates change in response to different conditions or in various states of health.

Oxygen Consumption Measurement

Measuring oxygen consumption is a key aspect of a wide range of biological research. The uptake of oxygen is not just a simple indicator of respiratory activity but also a direct measure of cellular respiration rate. Respirometers offer a method to track this oxygen usage by an organism over time. The principle behind the instrument involves capturing the gas exchange process — where oxygen levels decrease as it is consumed for metabolic activities, and carbon dioxide levels potentially increase as a byproduct. The measurements obtained are essential for calculating metabolic rates, assessing energy expenditure during exercise, and monitoring an organism's overall metabolic health. Particularly in clinical settings, oxygen consumption measurement is crucial for patients with respiratory or metabolic conditions, providing valuable insight into their physiological status.