Over time, the science of medicine has got better. Now few of us suffer much from infectious diseases like malaria or typhoid, and many of us live longer lives. But with age come new kinds of illness like Alzheimer's. Completely new kinds of medicines are needed to treat such illnesses.
Sometimes you may have seen an old gold ornament at home that has got spots or other signs of age. Your parents may take it to a 'polisher' to get it cleaned and polished. But did you know that the polisher actually removes a layer of gold?
If someone you know gets hurt and needs a lot of blood, you have to find a blood donor who has the same blood group. Did you wonder why this is so necessary? Why not anyone's blood? The answer lies in the chemistry of blood.
You'll have heard the fairy tale of Goldilocks - the girl who ate the Little Bear's Soup because it was neither too hot nor too cold. Well, life needs a planet just like that - neither too hot, nor too cold.