Cellular Respiration
Cellular respiration is the way living cells break down food and turn it into energy they can use.
A cell is like a small furnace box with wood stacked inside it. The wood is the food — sugar from what you eat. The box burns the wood and gives off heat, which is the energy the cell uses. Ash and smoke leave the box as waste, just like waste gas leaves the cell.
Explaining cellular respiration by grade level
Every living thing needs energy, even a small mealworm. A mealworm eats food and breathes in air. Inside its body, the food and air mix to make energy. The mealworm breathes out a gas, just like you do when you breathe out.
Projects that explore cellular respiration
You can watch a mealworm consume oxygen without any high-tech equipment. A simple respirometer built from a glass pipette and cotton does the job. Potassium hydroxide inside the tube absorbs carbon dioxide; as the mealworm uses oxygen, the air volume shrinks. A tiny dye bubble at the pipette tip moves inward to fill the gap. You measure how far the bubble travels every 30 seconds for five minutes, then use the distance and the tube's diameter to calculate how much oxygen the mealworm consumed.
Temperature changes how fast cells break down food for energy. Toads breathe by closing their nostrils, and you can count each breath over one minute. Cooling the water in ten-degree steps shows whether cold slows down the toad's breathing rate.