Answer:
Rhodopsin is the photopigment in rods.
I believe the answer to this question is a food web.
Food Web definition: "<span>a series of organisms related by predator-prey and consumer-resource interactions; the entirety of interrelated food chains in an ecological community."
Source: </span>http://www.dictionary.com/browse/food-web
In observing, we have our 5 senses (smell, taste, touch, see, hear) meaning scientists uses their 5 senses to be able to have a prediction or a hypothesis about the problem.
