Which plays both a role in physical and chemical digestion? a )teeth b) saliva c) gall bladder d) villi

Saliva

The saliva plays a role in both physical and chemical digestion.Physically saliva mixes with the food we intake and converts it into food bolus which has high moisture content as it has 98% water .Chemically saliva has enzyme amylase that converts starch into maltose and dextrin. Thus digestion starts from mouth even before it reaches the stomach.

littering streams           is the answer

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.