Describe an experiment to demonstrate that living organisms in soil respire, including the title, the role of lime water, expected observations, and an explanation of the results.

a) A suitable title for the experiment is: * To show that living organisms in soil respire / To investigate carbon dioxide production by soil organisms.

b) The purpose of lime water in the experiment is to detect the presence of carbon dioxide. It turns milky or cloudy in the presence of carbon dioxide.

c) After 5 hours, the following was observed: * A: The lime water in tube A turned milky/cloudy. * B: The lime water in tube B remained clear.

d) Explanation of the results: * In tube A, the moist soil contains living microorganisms (e.g., bacteria, fungi). These organisms carry out respiration, a biological process that releases carbon dioxide as a byproduct. The carbon dioxide produced diffused into the lime water, reacting with it to form insoluble calcium carbonate, which caused the milky appearance. * In tube B, the soil was baked, which killed most, if not all, of the living microorganisms. Therefore, there was no significant respiration occurring, and no carbon dioxide was produced. As a result, the lime water remained clear. This tube serves as a control to show that the carbon dioxide production is due to living organisms.