Answer:
<em>The correct option is D. It is carbon dioxide released by respiration.</em>
Explanation:
The process by which ATP is abundantly formed in organisms is termed as cellular respiration. Cellular respiration can be described as a process in which carbon dioxide and water are produced from glucose and oxygen. ATP molecules are synthesized by this process which are used for cellular activities.
Hence, the substance X in the investigation shows carbon dioxide which was produced when the yeast cells began to respire. Yeast cells can respire either in the presence of oxygen or without oxygen.
The independent variable is a variable that is affected by an experiment or another variable.
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