Misc: what line on a weather map links all points of equal pressure?

Questions

On what date does St George's day fall?

What is the name of the protein present in red blood cells that is scarlet when combined with oxygen?

Which pop group consisted of Eric Clapton, Jack Bruce & Ginger Baker?

The Puni, Jari and Xinga rivers are tributaries of which river?

What is the largest plant ever to have grown on the planet Earth?