Difference between arteries veins and capillaries

Explain the importance of producers, primary consumers, secondary consumers and decomposers in an ecosystem.

Ecosystems involve living organisms interacting with non-living things in a productive way; how is photosynthesis an example of this? answer, i will give brainiest to first person to get it right.

Which best describes the digestive system of arthropods? a incomplete, two openings b complete, one opening c two-way, one opening d one-way, two openings