Explain why a food web is a more realistic model of
energy flow than a food chain.

Food chain only shows one path by which energy can move through an ecosystem, because most organisms eat a variety of things, they are part of many food chains. A food web shows multiple pathways of energy, it shows interconnected food chains in a ecosystem.

Hope this helps

An easy way to calculate the amount of energy available at each level is to what?

Which of the following statements most accurately describes convergent evolution? the process in which two similar species evolve separately from each other and share similar characteristics the process in which a single species evolves into two or more new species the process in which two entirely different species evolve in response to each other the process in which two different species evolve separately from each other but still share similar characteristics

Ascience research group is testing a new type of plant food. one trial is conducted in a controlled experiment. the data from the trial show that the plant that received the new food grew faster than the control plant. the group announces that the new plant food makes plants grow faster. what is the main weakness in this scientific claim?