In order for fish to survive, the dissolved oxygen content of a lake or stream must be at least 3 µg mL-1. A particular lake has pH = 6.5 and T = 25oC. What is the molar DO concentration (no units req.)?

The human eye contains a molecule called 11-cis-retinal that changes shape when struck with light of sufficient energy. the change in shape triggers a series of events that results in an electrical signal being sent to the brain that results in vision. the minimum energy required to change the conformation of 11-cis-retinal within the eye is about 164 kj/mol.