Which statement best describes the purpose of Earth's spheres? They work together as open systems to cycle matter through ecosystems.
They work independently as closed systems to cycle matter through ecosystems.
They work together as open systems to move matter to living and nonliving parts of Earth.
They work independently as closed systems to move nutrients to living and nonliving parts of Earth.

4. multiple crosses were made between true-breeding lines of black and yellow labrador retrievers. all the f1 progeny were black. when these progeny were intercrossed, they produced an f2 consisting of 91 black, 39 yellow and 30 chocolate. a. propose an explanation for the inheritance of coat color in labradors. b. propose a biochemical pathway for coat color determination and indicate how the relevant genes control coat coloration.