The product of photosynthesis that is needed by both plants and other organisms for cellular respiration is glucose.

Here's why:

* Photosynthesis: Plants use sunlight, water, and carbon dioxide to produce glucose (a sugar) and oxygen.

* Cellular Respiration: Both plants and animals use glucose as a fuel source to create energy (ATP) through cellular respiration. This process involves breaking down glucose in the presence of oxygen to release energy.

So, the glucose produced by photosynthesis is essential for all living things, providing the energy necessary for life processes.