The plants in a red-tailed hawk’s food chain produce 3 million kcal of chemical energy per day. how much energy is available to the hawk’s trophic level, assuming 90% loss at each level?

The amount of total energy at each trophic level decreases as it moves through, so 90% is lost at each level. This means that only 10 percent of the energy at any trophic level is transferred to the next level; and the rest is lost as heat.  

In this case, if a plant ecosystem has 3000000 kilocalories (kcal) of energy, about 300000 kcal will be transferred to primary consumers (for example grass hoppers). If the red-tailed hawks are tertiary consumers, they will get 3000 kcal of energy.

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.