The livers have a good day! :))
The structure that surrounds the cell membrane of some cells, giving the cell a rigid shape is the cell wall.
The promise of jobs and prosperity, among other factors, pulls people to cities. Half of the global population already lives in cities, and by 2050 two-thirds of the world's people are expected to live in urban areas. But in cities two of the most pressing problems facing the world today also come together: poverty and environmental degradation.
