1. For the whole system, mechanical energy is conserved, but not just the ball. For the ball, there is an external force (elasticity) doing work for him, so the mechanical energy is not conserved, but for the whole system, there is no energy loss, so the mechanical energy is conserved.

2. For example, HCL in the molten state is nonconductive in the molten state, because compounds with valence of * * * will not ionize in the molten state. The definition of electrolyte is yes or no, that is to say, it is enough to meet one condition. Some substances will decompose in the molten state. Electrolyte refers to a compound that can be melted in an aqueous solution or can conduct electricity in a molten state, not necessarily in a molten state.

I haven't studied biology for a long time, I really don't know. I suggest you lose mitosis Baidu encyclopedia. The replication of DNA and the synthesis of protein should be that pollen is a germ cell only in interphase, and it can develop into an individual in pollen culture in vitro (colchicine treatment) to reflect the totipotency of cells.

4. Of course, it embodies omnipotence. Remember that as long as a cell is cultured into a plant, it embodies the totipotency of the cell, because it has to go through a process of plant tissue culture.

I hope to adopt.