Acell is a complex system. like most systems, a cell contains a boundary that separates things that are inside the system from those that are outside of the system. which part of the cell functions as a system boundary?

In plants, the cell boundary is the cell wall and the cell membrane. In animals, the boundary is the cell membrane and the cytoskeleton keeps the shape of the cell.

The soviet union beat the us to the first successful launch, with the october 4, 1957, orbiting of sputnik 1, and later beat the us to have the first human in earth orbit, yuri gagarin, on april 12, 1961. the "race" peaked with the july 20, 1969, us landing of the first humans on the moon with apollo 11

The vascular system