You should start studying a week before
Okay so there are two types of ERs, smooth and rough.
Rough endoplasmic reticulum contain ribosomes on the outer surface. It provides large surface area for proteinsynthesis and the synthesis of glycoproteins and also provides a pathway for the transport of materials.
Smooth ER synthesises, stores and transports lipids and carbohydrates.
Hope this helps
The cell membrane<span> is selectively permeable to ions and organic molecules and controls the movement of substances in and out of </span>cells<span>. The basic </span>function of the cell membrane<span> is to protect the </span>cell<span> from its surroundings. It consists of the phospholipid bilayer with embedded proteins.</span>
Yesssssssssssssssssssssirrrrr
I am not 100% sure but I thinking it responds when pathogens enter the body because the immune system is meant to protect your body from illness.
