Do all autotrophs use light is there energy source to make their own food like plants do with the sun

How many trophic levels are there in the following food chain? phytoplankton - shrimp - perch - pike - osprey

What are the characteristics of living things

Students in biology are studying the macromolecules of life. they used a calorimeter to determine the calories in various types of food. once the lab was completed, the students ate the left over food samples. monica commented that in just 6 or 7 "chews" of the saltine, it was gone; nothing but a sticky paste in her mouth. elaborate on what happened chemically while chewing the saltine. include the macromolecules present.