Deficiency of vitamin C results in softening of gums. 

Contaminated water and food is the mode of infection of cholera.

The inactive prorennin is converted to active rennin by HCl.

   A man cannot digest cellulose whereas cows can do so because their gut contains certain bacteria capable of digesting cellulose.

During diarrhoea, there is an excessive loss of water from the body along with salts and sugar. For this, WHO recommends a home-made solution of water with dissolved salt and sugar known as oral rehydration solution (ORS).

The process of digestion is facilitated by the release of digestive juices from some organs of the body. Pancreas, liver, small intestine and stomach are the organs which aid in digestion by releasing digestive juices. In large intestine, digestion does not take place because no juice is released by it to act upon food.

The working of a stomach was an accidental discovery by an American army doctor, William Beaumont, when he saved a man named Alexis St. Martin who was badly hit by a shotgun.

 Grass-eating animals eat fibrous food, which takes longer time to digest. That is why, they are also called ruminants. To digest the cellulose, they have a large sac-like structure between small intestine and large intestine. 

Molar teeth are known as wisdom teeth.

The food absorbed by blood needs to be transported to each and every organ of the body in order to be used to build the complex substances required by the body. This process is known as assimilation.

The digested food is absorbed by blood to provide energy. The digestion of food is completed in small intestine and then absorption of food starts with the help of numerous small finger-like projections present in the small intestine known as villi.

The food, which is not digested in the body of amoeba, is left as residue and expelled out of the body. 

In buccal cavity, there is no protein-digesting enzyme. In oesophagus, no digestion takes place at all. The digestion of proteins starts in the stomach due to the release of a protein-digesting enzyme called pepsin.

Stomach is a large J-shaped organ of alimentary canal, which is the widest part of the digestive tract. Large intestine, oesophagus and rectum are narrower and tube-like structures. 

The hard shell of sea animals is made of a chemical compound called calcium carbonate that protects them from mechanical injury.