A 20-kilogram river otter (a tertiary consumer) requires the energy harnessed by about kg of primary producers. Assume that 90% of the energy at each trophic level is lost as heat.

You are working in the lab and are working with the same element but with varying isotopes of the element. you are working with c-11, c-13, c-14, and c-15. what is the average atomic mass of this element? (use periodic table) a- 12 b-15 c-14 d-13