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.
Both plants and animals carry out metabolism, but they acquire the energy for this process by different means, i.e. plants employ photosynthesis and animal eat. Plant require very little energy compared to animals. Plant metabolic activities provide energy for transpiration, growth, etc.