Because measuring the amount of energy in each trophic level in an ecosystem is difficult, scientists often collectdata, which tells them the weight of living material at each trophic level. By weighing all the producers, herbivores, and carnivores in an ecosystem, a 90 percent loss of energy from one trophic level to the next has been observed.

answer; the correct answer is conflict- related aggression; +

a. by using fur or clothes to trap heat energy near the body

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.