1. Chemical influences on animal growth

2. Lead poisoning Inhibits the action of some enzyme, e.g. catalase Reduces plant growth Causes learning difficulties in young children Sources include petrol and lead piping

3. First symptoms of lead poisoning: vomiting, clumsiness, irritability and headaches. http://news.bbc.co.uk/1/hi/world/asia- pacific/8202429.stm http://news.bbc.co.uk/1/hi/world/asia- pacific/8202429.stm http://news.bbc.co.uk/1/hi/scotland/edinburg h_and_east/7055037.stm http://news.bbc.co.uk/1/hi/scotland/edinburg h_and_east/7055037.stm

4. Iron Component of : - haemoglobin - many enzymes and cytochrome Shortage leads to anemia

5. Iron deficiency

6. Calcium Obtained from milk products Component of shells, bones and teeth Needed for blood clotting

7. Vitamin D Obtained from milk Formed in the skin when exposed to sunlight Promotes the absorption of calcium from the intestine Required fro bone formation Shortage leads to deformed bones in young children (rickets)

8. Rickets (Vitamin D deficiency) http://www.thachers.org/rickets_photos.htm

9. Rickets (Vitamin D deficiency)

11. http://news.bbc.co.uk/1/hi/england/1936208. stm http://news.bbc.co.uk/1/hi/england/1936208. stm

12. Drugs Many drugs taken during pregnancy can pass across the placenta and affect the foetus -Thalidomide: anti-nausea drug, causes limb deformities

15. Drugs Many drugs taken during pregnancy can pass across the placenta and affect the foetus -Thalidomide: anti-nausea drug, causes limb deformities Alcohol: may retard growth and mental development. In extreme cases, foetal alcohol syndrome develops

17. Drugs Many drugs taken during pregnancy can pass across the placenta and affect the foetus -Thalidomide: anti-nausea drug, causes limb deformities Alcohol: may retard growth and mental development. In extreme cases, foetal alcohol syndrome develops Nicotine: may retard growth and mental development