Phase change is the change in state. i.e. water to steam or ice to water
Because they supply much energy to the food by preparing their own food because the above one can't prepare it own their own
The myelin sheath is the protective layer, which is present in the outer layer of the neural cells. This myelin sheath prevents the loss of electrical impulses, which are being conducted in the neurons. This also act as an insulator between neuron and its external environment.
This layer is mainly made up of the protein and fatty substance. The degeneration of the myelin sheath result in many neurological disorders.
Hence, the correct answer is myelin sheath.
Might be Cell Differentiation...
HI
The answer is : Appearance
I hope that's help !