3. Have all types of plants and animals always existed on Earth? How do you know? What evidence do scientists use to determine an animal first appears?

The rate that would change would be the  searching efficiency/attack rate. there are only two other rates in this model: the  growth rate of prey, and the  predator or consumer mortality rate.the  searching efficiency/attack rate is what indicates how effectively can a predator capture its prey whether in the searching process or actual capturing/attacking process. 

The principle of independent assortment describee how different genes independently separate from one another when reproductive cells develop.