A cell wall and a cell membrane are different. All cells are surrounded by a that is and interacts with the environment.

Cell Membrane---Semi-permeable

Explanation:

All cells have cell membranes, regardless of the type, and they are all semi-permeable, or selectively permeable, which means they can regulate what enters and leaves the cell.

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.