OCR GCSE Biology B · J257
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
Revise: Xylem and PhloemA thin transverse section of a broad bean stem lets light pass through it so that its tissues can be seen. One way to make the xylem easier to find is to stand a cut broad bean stem in eosin solution and allow the coloured solution to travel up the stem. Cut a thin section, place it in a drop of water on a microscope slide and lower a coverslip over it.