The cell membrane is a flexible structure that surrounds both plant and animal cells. The arrangement of molecules within the cell membrane makes it semi-permeable. That is, the cell membrane allows some substances to easily diffuse into and out of the cell, but it prevents the diffusion of other substances. Plant and animal cell diagram The cell wall is a rigid structure that surrounds plant cells. The materials found in the cell wall protect the plant cells and give plants structural support

african americans demonstrated their newly found freedom by relocating often in search of relatives whom they had been separated from during slavery. others established schools to educate freed people and they built institutions such as churches and political organizations to advocate for their rights.

they it depends on if one believes about radioactivity, they make a geiger counter beep but maybe it was going to beep anyway electronics do wierd things all the time or it was programmed to beep near certain metals.

colorless gas, exhibiting a blue glow when placed in an electric field

b) solid

its a type of rock