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Respiration: Investigation - Coggle Diagram
Respiration: Investigation
Using up oxygen during respiration: Simple respirometer.
This set up makes use of live, germinating seeds.
An apparatus as shown in the diagram is set up.
The test/ boiling tube on the right, contains germinating seeds, cotton wool, soda lime, and is attached to a manometer (with coloured liquid).
Cotton wool is present to prevent the passage of gases though the tube. The soda lime is present to absorb the carbon dioxide produced, so that it will be sure that any changes on the manometer are not caused by carbon dioxide.
The tube on the left is a control. The entire setup is in a water bath (37 degrees Celsius) to have moderate enzyme activity.
The initial and final readings on the manometer are recorded.
After sometime, it is observed that the level on the manometer has risen.
The level rises, since the oxygen is used up. This leads to a decrease in the air pressure, which pulls the liquid up.
Simple respirometer using a locust insect
The function of the soda lime and the cotton wool remans same. But instead of a manometer, a capillary tube is attached. This contains coloured/ colourless liquid with a drop of water.
For e.g. if you want to investigate the rate of respiration by varying temperature, then your independent variable would be temperature and the dependent variable would be the distance moved by the drop of water. Volume can be found by= Pie x r^2 x L (Where l= difference between the initial and final length).
Another way of carrying an investigation of temperature and the rate of respiration, a simple apparatus shown here can be set up. A constant temperature can be maintained by using a thermal water bath/ using a thermometer.
Energy release during respiration:
Apparatus contains: A thermometer, cotton wool, vacuum flask, germinating seeds (for the experiment) and dead seeds (as a control).
The germinating seeds are given a wash with 1% Formaldehyde solution. This is to kill any present bacteria.
The cotton wool is present to prevent the escape of heat.
In this experiment, the energy released is measured in the form of heat.
After 2 days, it will be observed that the temperature on the thermometer of the germinating seeds will have an increase. It will be enough to prove that this change is due to some reaction inside the system.
The control will dead seeds, will not show any change.
Anaerobic respiration in yeast:
The apparatus is set up as shown. It is kept in a water bath.
First, the glucose is boiled so that all the dissolved oxygen goes away. Then we must add powdered/ wet yeast. Glucose acts as a source of energy.
A layer of liquid paraffin is added, so that the oxygen does not enter. It will not allow oxygen to get it.
This paraffin is added through the screw clip and is closed during the experiment.
It is also connected to a test-tube filled with lime water.
The rubber bung is present to keep the screw clip and the tube in place, and not allow any gases to enter or exit.
We must maintain a no oxygen environment.
After sometime, the lime water turns cloudy. This is due to the production of CO2 during the anaerobic respiration. How does the CO2 get past the paraffin layer? This is because it is a liquid- to- liquid medium and it is easy to go through.