The energy needed by a system to initiate a process is called as the activation energy. It describes the minimum energy which must be available to a chemical system with potential reactants to result in a chemical reaction. Hope this answers the question.
<span>A person must inherit two copies of a defective CF gene -- one copy from each parent -- to have the disease. People who inherit only one copy are considered CF carriers and do not have the disease, but they can pass their copy of the defective gene on to their children.</span>