During which part of aerobic respiration is oxygen used?

Why did this plant use up all the oxygen in the water instead of producing it?

• I did a lab where we put a little plant in a small container and covered it in foil. The next day we opened the container and we tested the oxygen content, there was literally no oxygen in that container. And before we put the plant in and covered it there was plenty of oxygen Now i thought that plants produce oxygen not take it away....... i asked my teacher and she said its cuz of cellular respiartion. Can sum 1 explain in simple terms what cellular respiration is and why the plant used up all the oxygen?

• Answer:

  Right, put as simpley as possible.. when a plant photosynthesises, it creates sugars as a form of stored energy - It does this by converting carbon dioxide and water into sugars and oxygen... usually after photosynthesis, the plant will hold onto some of that oxygen for respiration and release the surpluss back to the atmosphere (however, shut the light out so it can nolonger photosynthesise, it runs out of oxygen then needs oxygen from else where) You see, this sugar is only good as STORED energy if you have a process where you can turn it into energy - respiration. Respiration requires oxygen in order to complete the reaction between sugars and nutrients particularly to create adenosine triphosphate (ATP) which is basically energy currency for cells... makes amazing things happen! So when you removed the light from the plant, it could no longer photosynthesise and create the oxygen byproduct, so when the oxygen ran out it took it from the water to keep its cells alive and healthy... when the sugar runs out though it's brown bread.