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.
Animals depend on plants for food as plants produce food and energy which animals can't, so, herbivores eat plants to get energy, carnivores eat herbivores and other carnivores for energy and omnivores eat all four, plants, herbivores, carnivores and also other omnivores for energy.
Photosynthesis. A primary difference between plants and animals is the plant s ability to manufacture its own food. In photosynthesis carbon dioxide from the air and water from the soil react with the sun s energy to form carbohydrates (sugars and starches). Photosynthesis literally means to put together with light.