Energy flow in an ecosystem follows the unidirectional transfer of energy from the sun to producers and then to consumers.
Key steps in energy flow:
Diagram:

Two important characteristics for estimating any population of animals and plants are \(\underline{\hspace{2cm}}\) and \(\underline{\hspace{2cm}}\) of individuals.
Demography is the study of factors that affect \(\underline{\hspace{2cm}}\) and \(\underline{\hspace{2cm}}\) patterns.