Examples would be the sensory system and nervous system, circulatory system and respiratory system, circulatory system and digestive system.
Digestive system digests food and absorbs it into blood vessels surrounding the gastro intestinal tract. Nutrients are taken by blood to the heart and pumped to all organs for use.(circulatory systems function).
Notice that the equation for cellular respiration is the direct opposite of photosynthesis: Cellular Respiration: C6H12O6 + 6O2 → 6CO2 + 6H2O. Photosynthesis: 6CO2 + 6H2O → C6H12O6+ 6O.