All elements of a ecosystem work together, the sun provides sun light which plants use photosynthesis for food. Small animals eat the producers aka the plants. Then other animals eat those. And so on if a plant wasn't alive then the whole ecosystem will fail.
Semipermeable means only certain substances can pass through. I imagine you are talking about cell membranes which are semipermeable. This means vital things like oxygen and nutrients are able to pass through the membrane, while not allowing everything to enter the cell
According to the 2011 Earth Science Reference Table, Selenite Gypsum has an approximate hardness of 2.
The hardness of calcite is 3.
The hardness of apatite is 5 according to the Moh's hardness scale.
The hardness of diamond is 10.
Cell membrane i think as I remember
