FREE NEET Biology Practice MCQ Test: Digestion And Absorption Exercise 2 Questions Answers With Detailed Explanations [PDF]

Answer: (c)

The secretion of the cells of the gastric glands form gastric juice with pH 2 to 3.7. It contains two proenzymes, pepsinogen and prorennin and enzyme gastric lipase, mucous and hydrochloric acid. Rennin (chymosin) is responsible for clotting milk by acting on soluble milk protein caseinogen, and converting it into insoluble casein. This ensures that milk remains in stomach long enough to be acted on by protein digesting enzymes. Rennin's concentration is highest in young mammals (as their primary diet is milk) which reduces gradually with age.

Answer: (a)

Liver is the largest digestive gland. Hepatic lobules are the structural and functional unit of liver. Liver is basically an organ of homeostasis. Which controls many metabolic activities essential for maintaining constant blood composition. Kupffer cells (present in the lining of blood spaces of liver) are phagocytic and involved in the breakdown of old red blood cells and ingestion of potentially harmful bacteria. Glissons capsule is a thin layer of dense connective tissue which surrounds the liver lobule enclosing branches of portal vein, the hepatic artery, the bile duct and lymphatic capsule. Crypts of Lieberkuhn (present in the intestine) are tubular invagination of the epithelium around the villi, lined largely with younger epithelial cells which are involved primarily in secretion.

Answer: (d)

Answer: (d)

Answer: (c)

Answer: (d)

Milk/primary teeth of man include 8 incisors, 4 canines and 8 molars (premolars are absent). Molars of milk teeth are shed off and premolars of permanent teeth take their place. The permanent teeth are 8 incisors, 4 canines, 8 premolars and 12 molars. Thus 12 teeth (8 premolars and 4 molars) are monophyodont (teeth which grow only once in life). Dental formulae of milk teeth and permanent teeth of human are given below.

${2102}/{2102}$ × 2 = 20 - Milk teeth

${2123}/{2123}$ × 2 = 32Permanent teeth

Answer: (a)

Answer: (c)

The absorption of glucose and amino acids is mediated by carrier ions like $Na^{+}$ . The concentration of $Na^{+}$ is higher in the intestinal lumen compared to mucosal cells. $Na^{+}$ , therefore moves into the cells along its concentration gradient and simultaneously glucose is transported into the intestinal cells. Thus $Na^{+}$ diffuses into the cell and it drags glucose along with it. The intestinal $Na^{+}$ gradient is the immediate energy source. The mechanism for transport of amino acid is same as glucose.

Fructose absorption does not require energy and is independent of $Na^{+}$ transport.

Answer: (c)

Indigestion is the condition in which the food is not properly digested leading to a feeling of fullness. The causes of indigestion are inadequate enzyme secretion, anxiety, food poisoning, overeating and spicy food.

Answer: (c)

Deficiency of rhodopsin in eyes occurs due to deficiency of vitamin A. Carrot and ripe papayas are rich sources of vitamin A so these should be eaten in deficiency of rhodopsin in eyes.

Answer: (c)

Answer: (c)

The yellow colour is due to the presence of bile pigments (bilirubin-yellow). Bile pigments are excretory products. Bile is a bitter-tasting greenish-yellow alkaline fluid produced by the liver, stored in the gall bladder, and secreted into the duodenum of vertebrates. It assists the digestion and absorption of fats by the action of bile salts, which chemically reduce fatty substances and decrease the surface tension of fat droplets so that they are broken down and emulsified.

Answer: (b)

Thromboplastin, a lipoprotein, helps in clot formation. Thromboplastin helps in the formation of an enzyme prothrombinase. This enzyme inactivates heparin and it also converts the inactive plasma protein prothrombin into its active form, thrombin. Both the changes require calcium ions. Thrombin converts fibrinogen molecule to insoluble fibrin. The fibrin monomers polymerize to form long, sticky fibres. The fibrin threads form a fine network over the wound and trap blood corpuscles (RBCs, WBCs, platelets) to form a crust, the clot.

Answer: (b)

Answer: (d)

Answer: (a)

The abnormal frequency of bowel movement and increased liquidity of the faecal discharge is known as diarrhoea. It reduces the absorption of food.

Answer: (a)

Answer: (b)

Parotid glands are the largest salivary glands. They lie on the sides of the face, just below and in front of the ears. The parotid ducts, also called Stenson's ducts, open into the vestibule opposite the upper second molar teeth.

Answer: (d)

Answer: (d)