Please enter valid positive numbers for all fields.
Volume of Oxygen Consumed
0 mm³
Absolute Rate of Respiration
0 mm³/min
Mass-Specific Respiration Rate
0 mm³/min/g
function calculateRespiration() {
// Get input values using var
var diameter = parseFloat(document.getElementById('resp-diameter').value);
var distance = parseFloat(document.getElementById('resp-distance').value);
var time = parseFloat(document.getElementById('resp-time').value);
var mass = parseFloat(document.getElementById('resp-mass').value);
var errorMsg = document.getElementById('error-msg');
var resultContainer = document.getElementById('result-container');
// Validation
if (isNaN(diameter) || isNaN(distance) || isNaN(time) || isNaN(mass) ||
diameter <= 0 || distance < 0 || time <= 0 || mass <= 0) {
errorMsg.style.display = 'block';
resultContainer.style.display = 'none';
return;
}
errorMsg.style.display = 'none';
// Calculation Logic
// 1. Calculate Radius (r = d/2)
var radius = diameter / 2;
// 2. Calculate Volume of cylinder (V = π * r² * h) where h is distance moved
// Result in cubic millimeters (mm³) which is equivalent to microliters (µL)
var volume = Math.PI * (radius * radius) * distance;
// 3. Calculate Rate (R = V / t)
var rate = volume / time;
// 4. Calculate Specific Rate (R_spec = R / m)
var specificRate = rate / mass;
// Update DOM
document.getElementById('res-volume').innerHTML = volume.toFixed(4) + " mm³";
document.getElementById('res-rate').innerHTML = rate.toFixed(4) + " mm³/min";
document.getElementById('res-specific-rate').innerHTML = specificRate.toFixed(4) + " mm³/min/g";
resultContainer.style.display = 'block';
}
How to Calculate Rate of Respiration Using a Respirometer
Calculating the rate of respiration using a respirometer is a fundamental skill in biology, particularly when studying the metabolic rates of small invertebrates (like woodlice or maggots) or germinating seeds. A respirometer measures oxygen consumption over time, allowing researchers to quantify aerobic respiration.
Understanding the Respirometer Setup
A simple respirometer consists of a sealed chamber containing the living organism and a substance (usually Potassium Hydroxide – KOH) to absorb the carbon dioxide produced. As the organism respires, it consumes oxygen ($O_2$) and releases carbon dioxide ($CO_2$).
Since the $CO_2$ is absorbed by the alkali, the overall volume of gas in the chamber decreases. This drop in pressure causes fluid in an attached capillary tube (manometer) to move toward the chamber. By measuring this movement, we can calculate the volume of oxygen consumed.
The Calculation Formulas
To convert the linear distance the fluid moves into a volumetric rate of respiration, we treat the capillary tube as a cylinder. The calculation involves three main steps:
1. Calculate the Volume of Oxygen Consumed
First, determine the volume of the cylinder of liquid that moved. You need the radius of the capillary tube ($r$) and the distance moved ($d$).
Volume ($V$) = $\pi \times r^2 \times d$
Note: If you have the diameter (bore size), divide it by 2 to get the radius. Ensure your units are consistent (e.g., all in mm).
2. Calculate the Absolute Rate
Divide the total volume consumed by the time elapsed to find the rate per minute.
Rate ($R$) = Volume ($V$) / Time ($t$)
3. Calculate the Mass-Specific Rate
To compare respiration rates between different organisms, you must account for their size. Divide the absolute rate by the mass of the organism.
Specific Rate = Rate ($R$) / Mass ($m$)
Example Calculation
Let's say you are observing germinating mung beans in a respirometer: