I need help, if you can explain.​

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important

18. which statement about cancer is true?

Grasses--> mice--> cats--> coyotes suppose 10,000 units of energy are available at the level of the grasses. what is the total number of energy units lost by the time energy reaches the coyote?