Question of the week: What is the most important scientific discovery of the past 100 years?

Emily Law Hoi-tung, 17

SKH Bishop Mok Sau Tseng Secondary School

The discovery of penicillin. In 1928, Sir Alexander Fleming observed that some bacteria were destroyed by the mould Penicillium notatum. When put to medical use, penicillin proved to be a miracle in world war two by preventing infection in wounds - the biggest wartime killer. Millions of lives have been saved by it since then. Penicillin is still used today to heal wounds. If it had not been discovered, people would suffer from infections a lot more.

Mandy Chu Ka-man, 17

SKH Bishop Mok Sau Tseng Secondary School

The discovery of DNA. Watson and Crick proposed the notion of the double helix molecular model for DNA in 1953. This was the starting point from which scientific research on DNA and genetics grew in the latter half of the 20th century. The discovery enables us to understand genetic diseases and develop genetically modified foods - and even clones. Different types of technology have been developed because of the discovery. Some of them bring benefits while others may be harmful to us. It is a field worth exploring.