What assumption might students mistakenly make when measuring the release of bubbles from a pondweed stem?

The assumption that bubbles contain only oxygen stems from a common understanding of the photosynthesis process, where oxygen is produced as a byproduct. Students may oversimplify the experiment by focusing solely on oxygen release, neglecting that other gases such as carbon dioxide or even trapped air might be present in the bubbles. This view fails to recognize that when measuring gas release from pondweed, multiple factors and variations could affect the composition of the bubbles, leading to inaccurate conclusions regarding the photosynthesis rate. Understanding that bubbles can consist of different gases is crucial for interpreting the results correctly, hence this assumption is often misleading in a scientific context.