Question

why would a bottle kept in the dark have less dissolved oxygen than one in the light? respiration continues but photosynthesis stops organisms stop respiring light prevents oxygen use

Explanation:

In the dark, photosynthesis in plants or photosynthetic organisms stops as it requires light. However, respiration continues in all organisms (including plants and other aerobic - organisms in the bottle), consuming oxygen. In the light, photosynthesis can produce oxygen which can replenish the oxygen used in respiration.

Answer:

Respiration continues but photosynthesis stops