Unit 2- Chemical and Cellular basis of life

Introduction

Living things are made up of cells. Cells are made up of elements mainly; C, N, O,H,P and S. Therefore living things are made up of elements and among the 92 naturally occurring elements, Living matter consists of about 20 elements.There are two types of elements that occur in living things.

Trace elements – Needed in low amounts but are essential.

                                e.g.  Mn, Zn, Cu, Mo, B, Al, Si, V (in plants, Na, Fe, Cl)

Macro elements – Needed in large amounts

                               E.g.  H,C,N,O,P,S,K, Ca, Mg,(in plants)

                                       H,C,N,O,P,S,K, Ca, Mg ,Na, Fe, Cl ( In animals)