What is the benefit of a bird migration? The cost?

How do tides affect the organisms living in intertidal zones? a. no organisms live in intertidal zones due to the tumultuous environment. b. the mechanical forces of the waves keeps the organisms clean. c. only plants live in intertidal zones because the animals float away with the waves and never return. d. the mechanical forces of the waves can dislodge the organisms from their habitat.

According to the cladogram, which organisms have roundworms as a common ancestor?

What are the doorways into and out of cells, attached to the membrane, and built in the rough er.