Name the nutrients which are completely digested in the small intestine.

Most of the digestive enzymes in the small intestine are secreted by the pancreas and enter the small intestine via the pancreatic duct. The three major classes of nutrients that undergo complete digestion in the small intestine are proteins, lipids (fats), and carbohydrates.

What is the role of (1) teeth and (2) tongue in digestion?

(1) Teeth - When the food is consumed in the mouth, the teeth break the food into smaller pieces. This process is also known as mastication – the process of cutting, tearing, and grinding the food in the mouth and mixing it with the saliva, so it can be swallowed easily before it enters the body. (2) Tongue - The tongue helps out, pushing the food around while chewing with the teeth. When ready to swallow, the tongue pushes a tiny bit of mushed-up food called a bolus towards the back of the throat and into the opening of the oesophagus, the second part of the digestive tract.

Name the main organs of the human digestive system in the order to the digestion of food.

Digestion is the process by which large insoluble food molecules are broken down into little water-soluble food molecules that may be absorbed into the watery blood plasma. The main organs of the human digestive system in order to the digestion of food are the mouth, oesophagus, stomach, small intestine, large intestine, rectum, and anus. It also contains the salivary glands, liver, gallbladder, and pancreas, which produce digestive juices and enzymes that aid in the digestion of food and liquids. The digestive system's six primary functions are ingestion, propulsion, mechanical breakdown, chemical digestion, absorption, and excretion or elimination.

In the given diagram, name the following parts (i), (ii), (iii) and (iv).

The heart is a muscular organ the size of a fist that is located right behind and slightly to the left of the breastbone. The heart circulates blood through the cardiovascular system in the body, which is a network of arteries and veins. Part (i) in the diagram represents the right atrium. Part (ii) in the diagram represents the aorta. Part (iii) in the diagram represents the pulmonary artery (left). Part (iv) in the diagram represents the left ventricle.