If HCl would not be secreted then there will be following effects :
1. Pepsinogen will not be activated and no digestion of proteins will take place in the stomach.
2. Germs may flourish in stomach in the absence of HCl.
3. Milk will not be coagulated, because prorennin is converted into rennin by the action of HCl.
Diphyodont is the condition of having two set of teeth during the life of an organism. For example : humans are diphyodont as they have two set of teeth namely temporary milk or deciduous teeth which are replaced by permanent or adult teeth.