About 30 per cent of starch is hydrolysed by the enzyme at optimum pH 6.8 into a disaccharide –maltose.

Lymph capillaries pick up the excess interstitial fluid & proteins and return them to the venous blood. 
The blood capillaries absorb most nutrients, but the Fats & Fat-soluble vitamins are absorbed by the lacteals.
The lymph in the lacteals has a milky appearance due to its high Fat content & is called chyle.

(i) People who are lactose intolerant cannot digest food with lactose in them.
(ii) These people need to take a calcium supplement which is naturally present along with lactose in milk.

Hence, option C is correct.

The bolus is conveyed into the pharynx and then into the oesophagus by swallowing or deglutition.

• Chymosin, known also as rennin, is a proteolytic enzyme related to pepsin that synthesized by chief cells in the stomach of some animals.
• Its role in digestion is to curdle or coagulate milk in the stomach, a process of considerable importance in the very young animal.
• If milk were not coagulated, it would rapidly flow through the stomach and miss the opportunity for initial digestion of its proteins

Liver, pancrease and salivary gland are digestive gland that release enzymes for digestion of food but thyroid gland release thyroxin hormone that help in metabolism of carbohydrates, proteins and fats.

Liver convert glucose into glycogen and store glycogen. Once storage limit is reached then extra carbohydrates will be converted into fats.

The bile duct and the pancreatic duct open together into the duodenum as the common hepato-pancreatic duct which is guarded by a sphincter called the sphincter of Oddi.

The process of conversion of complex food substances to simple absorbable forms is called digestion.

Serosa is the outermost layer while mucosa is the innermost layer.
The layer next to mucosa is the sub-mucosa containing nerves, blood and lymph vessels. Muscularisis found between sub-mucosa and serosa.

Tetanus is not a common disorder associated with digestive system.

Trans-fats are made when food makers turn liquid oils into solid fats, like shortening or margarine.
(i) Trans-fats can be found in many fried, "fast", packaged, or processed food.
(ii) Partial hydrogenation of vegetable oils is done to make fats more solid at room temperature, to increase their shelf life by keeping their flavor stable over longer periods of time, and to guard against spoilage.
(iii) Trans-fats are worst type of fats.

Hence, option A is correct.

(i) Ruminants have a four-chambered gut, and these microorganisms live primarily in the rumen. One particularly important bacterial genus that takes part in the degradation of cellulose is gram positive Ruminococcus.
(iii) Some ruminants like camel and deer do not have omasum. The omasum is the third chamber in the ruminant stomach. Function of the omasum is absorption.

Hence, Staement (i) and (iii) are correct.

It is difficult to remove stone surgically and by lithotripsy. So, in most of the cases gall bladder is removed surgically.

Diastema is the gap between the teeth of human beings.
Generally, diastema is not present in human beings. 

The wall of alimentary canal from oesophagus to rectum possesses four layers namely serosa, muscularis, sub-mucosa and mucosa.

Mucosa layer forms irregular folds (rugae) in the stomach and small finger-like foldings called villi in the small intestine

Numerous folds present on the inner surface of the stomach are called rugae. They are series of ridges produced by folding the wall of an organ.

Another part of the digestive tract which contains rugae is the palate, the top part of the inside the mouth.

Zymogen is an inactive enzyme precursor that require biochemical change to become active. Amylase enzyme is not released from its source in the form of proenzyme or zymogen.

5 g of protein = 5 x 4 = 20 calories
4 g of fat = 4 x 10 = 40 calories
10 g of carbohydrates = 10 x 4 = 40 calories.

Total energy produced = 20 + 40 + 40 = 100 calories.

Medulla oblongata consist of a accumulation of nerve cells act as vital centres of many reflexes like vomiting, sneezing, coughing.

(i) Blood vessels of the alimentary canal provide nourishment to the cells of the alimentary canal.
(ii) Blood vessels of the alimentary canal do not absorb digested fat molecules from the stomach and intestine.

Fats, protein, and alcohol on oxidation produce energy along with other products but vitamins are not oxidized to release energy to us.

Porphyromonas gingivalis bacteria is responsible for periodontal disease of mouth. Paodontax toothpaste help to prevent periodontal disease.

The main constituent of gastric acid is hydrochloric acid which is produced by parietal cells (also called oxyntic cells) in the gastric glands in the stomach