In the latter case the resistance is caused by dissipation of mechanical energy when the configuration or the direction of flow is sharply changed, by the formation of vortices and secondary flows as a result of the flow breaking away, by the centrifugal forces, etc.
Why do animals depend on plants. Plants give animals the food and shelter they need. Herbivores, which are plant eating animals, rely on plants to provide them with a regular source of food. They also provide shelter to may animals, both large and small.
#2. phyzguy Science Advisor. The nutrients that plants get from the soil don't generally include living organisms. For the most part, plants don't require eating other organisms as a source of energy, and animals do. Most plants get their energy from the sun instead of eating other organisms. There are some exceptions, like Venus fly-traps, which are plants that eat insects for nutrients (not for energy), and animals like worms that eat primarily dead organic matter.