1. The cell wall has lignin (hard substance): to prevent the xylem vessel from collapsing and withstand high pressure.
2. The absence of protoplasm (nucleus + cytoplasm) and cross wall: to allow water to move through the lumen easily.
Hope it helped!
It is an organic substance.
I believe you meant 'selective breeding'.
Selecitve Breeding is when say a dog breeder, chooses two prospective parents in hopes of achieveing a superior offspring or offspring with desired traits.
It would turn into GCCATG
