Carbonic acid dissolved in water is a a. Biological weathering agent
b. Chemical weathering agent
c. Mechanical weathering agent
d. Physical weathering agent

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.