You have performed a serial dilution of a sample with an unknown concentration of microorganisms. You counted 73 CFU on a countable plate inoculated with 0.1 mL of a 10-3 dilution. What was the population density of the original sample per milliliter?

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.