Question

why do we need a tissue

Answer 1

Its necessary because without tissue there will will be organ and organ system and without organ system There will be nothing and there will be no life

Answer 2

We need tissue in our body...it's a group of similar looking cells...there are some specialised tissue in our body which perform some special functions afflicted to them...for more efficient working of our body tissues are required.
for e.g. -connective tissue like blood.