Notes: 1  When s is a string or Unicode string object the in and not in operations act like a substring test. In Python versions before 2.3, x had to be a string of length 1. 2  Values of n less than 0 are treated as 0 (which yields an empty sequence of the same type as s).
A food web describes the flow of energy and nutrients through an ecosystem, while a food chain is a linear path through a food web. Distinguish between food chains and food webs as models of energy flow in ecosystems. Organisms can be organized into trophic levels: primary producer, primary consumer, secondary consumer, and tertiary or higher-order consumer.
By Anne Marie Helmenstine, Ph.D. Energy is defined as the ability to do work. Energy comes in various forms. Here are 5 main types of energy and examples of them. 1  mechanical energy. 2  Mechanical energy is energy that results from movement or the location of an object.