Write 2 experiments that proves that oxygen is used up in respiration.Explain in detail how does this done and what are the things used?

Question

Michael Adams · Accepted Answer

One method is using a respirometer with woodlice or another small organism inside it, another method is using a spirometer

Respirometer apparatus can be set up as shown:

This involves two containers, connected by a capillary tube containing a coloured fluid (a manometer).

A live organism (eg a woodlouse) is placed in one container, along with a #CO_2# absorbent (eg potassium hydroxide solution) to remove any #CO_2# produced by the respiring organism.

A glass bead of equal mass and volume is placed in the other container to ensure both containers are identical in every way other than the presence of the organism, so that the only variable is the amount of #O_2# consumed.

As the organism present respires, it will consume #O_2#, causing the pressure of the gas in the container on the left-hand side to decrease, drawing the coloured fluid in the manometer up into the left side. The distance moved by the coloured fluid can then be used to calculate the volume of #O_2# that was lost from the left container, if the width of the manometer tube is known. This is done using the equation for the volume of a cylinder #V = pir^2h#. The average rate of #O_2# consumption can then be measured by dividing the volume of #O_2# consumed by the time.

Similarly, spirometer apparatus can be set up as shown:

A spirometer works in much the same way as a respirometer. A patient inhales in and out of the mouthpiece. Any #CO_2# they breathe out is absorbed by a #CO_2# absorbant, so the only change in the inside of the spirometer is a gradual decrease in #O_2# present as more and more of it is absorbed by the patient.

An image trace as shown is produced:

As the patient exhales, the volume of the spirometer increases, and vice versa as the patient inhales. This causes the peaks and troughs shown on the graph. The average volume of the spirometer gradually decreases as #O_2# is absorbed by the patient.

The rate at which the graph decreases (ie the gradient of the trend line) can be found - this gives a rate for average #O_2# consumption, in #dm^3 s^-1#.

Connor Abernathy · Answer

undefined Experiment 1:
1. Set up a respirometer consisting of a sealed chamber with a small organism (such as a germinating seed) and an alkali to absorb carbon dioxide.
2. Place the respirometer in a water bath and measure the volume of oxygen consumed by the organism over a period of time by the displacement of water in a graduated tube connected to the respirometer.

Experiment 2:
1. Utilize a burning candle in a sealed container with a known volume of oxygen.
2. Measure the decrease in volume of oxygen as the candle burns, indicating that oxygen is being consumed through respiration.

Both experiments demonstrate oxygen consumption during respiration by measuring the decrease in available oxygen over time. The first experiment uses living organisms in a controlled environment, while the second experiment utilizes a chemical reaction (burning candle) to show oxygen consumption.