Explanation

Silicon is almost negligible in living organism. A comparison of elements present in non-living and living matter is as follows [table] Element | % Weight of Earth’s crust Human Body ; Hydrogen (H) Carbon (C) Oxygen (O) Nitrogen (N) Sulphur (S) Sodium (Na) Calcium ($Ca$) Magnesium (Mg) Silicon (Si) | 0.14 0.03 46.6 Very little 0.03 2.8 3.6 2.1 27.7 | 0.5 18.5 65.0 3.3 0.3 0.2 1.5 0.1 negligible [/table] *Adapted from CNR Rao, Understanding Chemistry Universities Press Hyderabad