Answer:
Vacuum
Explanation:
A vacuum is usually defined as a space in which there is an absence of matter. It can also be said that there is an extremely low amount of pressure due to which the particles present in it are not affected by any type of process that occurs in space. The value of pressure is lower than the value of normal atmospheric pressure.
For example, sound cannot travel in space because there is no medium such as water and air through which the sound waves can propagate.
Cell membrane i think as I remember
Answer:
plant cells have a rigid cell wall that helps it keep shape and animal cells don't
Secondary succession occurs after the initial succession has been disrupted and some plants and animals still exist. The disruption occurs afer an event like a forrest fire or hurricane destroys the forest.
They use the algae in the water
