First, he should measure how long it takes for the liquid to become clear if X and Y are mixed together. Then, he should measure how long it takes if he also adds substance A to X and Y. He will find out if substance A is a catalyst. hope this helps :)
The best answer is B (semi permeable)
The cell membrane of a red blood cell is semi permeable membrane. This is a type of biological membrane that will allow certain molecules or ions to pass through while barring others.
Red blood cells have very thin membranes that allow oxygen diffuse through quickly. They are also permeable to water and osmosis across the membrane occurs very rapidly. In the body, they are bathed in isotonic plasma in which case water movement into the cell is equal to water movement out of the cell and so the cells remain intact.
<span>The plasma membrane is phospholipid bilayer. The layers are two and are continuous flat sheets. They have proteins and cholesterol embedded in them, for facilitating the transport of compounds and maintanng fluidity. The lipid bilayer is both hydrophobic and hydrophillic. </span>
Answer:
HEYYYYYYYDYSYYSYSUSUSISIDID
