Question

Why is the stem of a plant, called two way traffic

Answer 1

because food and minerals are transported by xylem tissue and prepared food is transported by phloem tissue in different directions just like a two way traffic inside the stem

Answer 2

Answer:

Scientists want to have a variety of stem cell lines so that they can pick the best ones for their experiments. Some lines are better suited for becoming pancreatic cells, others for neurons (no one is sure why). Moreover, older cell lines are harder to grow, and many contain mutations and chromosomal abnormalities.