Suppose you scraped off some of the pale green stuff from the tree bark. How would you know whether it was alive or not? What observations would you note? What tests could you do to see whether it’s alive?

Which statement is true about the model of the electromagnetic spectrum a: it change the frequencies of light. b: it compare wavelengths of light. c: the color of light waves can be changed using the model. d: the intensities of light waves can be decreased using the model.