Answer:
Explanation:
In biological membranes, substances are usually moved in and out, in order to ensure healthy development of cells and organism. These membranes are made up of a two lipid layer and often permit lipid-soluble substances easier movement.
Different types of movement occurs, they are PASSIVE and ACTIVE TRANSPORT. Passive transport of solutes occurs spontaneously (without energy supply) following concentration gradient and/or a carrier protein.
On the other hand, Active transport involves transport of solutes with the help of specific "vehicle" called carrier proteins ONLY in the presence of energy, and AGAINST concentration gradient.
Because ACTIVE TRANSPORT requires energy (in form of ATP) to drive its transport, it DOES NOT occur spontaneously in biological membranes.
