Night blindness is caused by the deficiency of vitamin A.

Steps involved in the digestive system are- ingestion, digestion, absorption, assimilation, and egestion. Excretion is not a process of the digestive system, but is a process of the excretory system.

Liver produces bile, whereas pancreas secretes pancreatic juice and stomach produces HCl. The function of the gallbladder is to store the bile. So, option (4) is the correct answer.

Taste buds help humans to taste diiferent types of food.

The inner lining of the stomach secretes mucus, which protects the inner membrane from the action of HCl.

In birds, jaws are modified into beak and teeth are absent..

Tongue can move in all directions. The back of the tongue is attached to the floor of the buccal cavity.  It is a fleshy muscular organ. It mixes saliva with food.  So, option (2) is the correct answer.

In carnivores, canines are well developed to pierce and tear flesh.

Humans and amoebae have similar process of ingestion, i.e. they engulf the whole food. Both of them have holozoic mode of nutrition.

The main function of HCl is to convert the pepsinogen (inactive form) to pepsin (active form). Pepsin is an enzyme which is involved in the breakdown of proteins. So, if HCl is not secreted, digestion of proteins cannot take place.

Maximum absorption of water takes place in the large intestine.

Formation of faeces takes place in the large intestine where water is absorbed from the undigested material, resulting in the formation of solid waste called as faeces.

The finger-like projections of amoeba are called pseudopodia which helps them to engulf food.

The passing of watery stools from the body is known as diarrhoea, which leads to dehydration, i.e. excess loss of water from the body.

Grass is a fibrous food and takes more time for digestion. In grass eating animals, there is a separate part of stomach called rumen. That is why, these animals are also known as ruminants.