Question

List 3 examples of a selectively permeable material or item. Explain where it is found or used and why a selectively permeable item is needed

Answer 1

Answer;
Examples of selectively permeable materials or items are; 
1. Vacuum filter- it traps dust but allows air through
2. Coffee filter- allows water to pass through, but does not allow the coffee grounds.
3. Colander -used to strain liquid food from foods. it drains water but is not permeable to larger food particles.

Explanation;
Selective permeability means that a material or a substance allows the passage of some molecules or ions and other materials to pass through it, and inhibits the passage of others. 
For example a cell membrane is semi-permeable and thus regulates the transport of materials such that some particles pass through while others can not cross. A semi-permeable membrane allows selective movement of materials, it acts like a filter that allows particles to pass or not according to their size, solubility, electrical charge, or other chemical and physical properties. 

Answer 2

I have this question for homework as well.
Colander - drains water but isn't permeable enough to lager food (used to strain liquid from food)
Vacuum filter - traps dust but allows air through (used to clean)
Coffee filter - allows air through (used to make coffee)