You're either talking about Community which means grouping of different organs or population which is the grouping of the same organ
Selective permeable means it selects what goes out and comes into the cell. If the cell membrane wasnt selective then things could enter the cell and destroy it.
-Seth
The speed of sound<span> is greater in hot </span>air<span> than it is in </span>cold air<span>. This is because the molecules of </span>air<span> are moving faster and the vibrations of the </span>sound<span> wave can therefore be transmitted faster. This means that when </span>sound travels<span> from hot </span>air<span> to </span>cold air<span> or from </span>cold air<span> to hot </span>air<span> it will refract.</span>
The difference is very small, if it exists at all. Please Mark Brainliest!