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.
energy, heat flow, and life Energy, in the process we call heat or heat flow, is constantly flowing into and out of all objects, including living objects. Heat flow moves energy from a higher temperature to a lower temperature. The bigger the difference in temperature between two objects, the faster heat flows between them. When temperatures are the same there is no change in energy due to heat flow. Radiation and Conduction are the two methods of heat transfer. Convection is a special type of conduction. Heat has the units of energy; heat flow has the units of power.