Answer:
1. xylem transport water .... phloem transport food(ions,startch)
direction of transport in xylem is unidirectional while its bidirectional in phloem
2. pore/opening between guard cells which allow air exchange
3.because epidermal tissue has function of protection,if space exist in cell it create pores for pathogen to enter and protection function cant be performed
4.because blood is composed of cells and extracellular matrix,a primary requirement to be a connective tissue