No, glucose is not oxygen for plants. Instead, glucose is a sugar that plants produce through the process of photosynthesis. During photosynthesis, plants take in carbon dioxide from the air and water from the soil, and using sunlight (light energy), they convert these into glucose and oxygen.
The overall equation for photosynthesis can be summarized as follows:
\[ \text{6 CO}_2 + \text{6 H}_2\text{O} + \text{light energy} \rightarrow \text{C}6\text{H}{12}\text{O}_6 + \text{6 O}_2 \]
This means that six molecules of carbon dioxide and six molecules of water, with the help of light energy, are converted into one molecule of glucose and six molecules of oxygen. The glucose produced is used by the plant as an energy source and as a building block for growth. The oxygen is released into the atmosphere as a by-product.