WAEC - Biology (2009 - No. 16)
A group of rats placed in an air-tight box for some hours died because they
breathed in air containing nitrogen.
produced carbon dioxide
ran short of energy
used up the available oxygen
توضیح
Rats, like all mammals, require oxygen to survive. They breathe in oxygen and breathe out carbon dioxide, a process known as respiration. In an air-tight box, the available oxygen would eventually be used up, and the rats would die from lack of oxygen, not from the presence of carbon dioxide or nitrogen, or from running out of energy.