<span>False. The plasma membrane is the outer layer of the membrane and its primary purpose is to protect the cell from its surroundings. It is selectively permeable to allow ions and other organic molecules to pass through and regulates which molecules are allowed in and out of the cell. It is a phospholipid bilayer that are placed back-to-back.</span>
Whether you put the bread in the shade or the Sun aka the environment.
In the lock and key model of enzyme action, the substrate fits into the active site of the enzyme, then after undergoing a conformational change, it will release the substrate and produce a product.
<span>It would be replaced in cases where new information and evidence would be discovered that completely contradicts the old information and evidence. Then you couldn't revise it because revision incorporates the old evidence that would now be obsolete. Then you would make a completely new theory.</span>