57 Questions with Answers and Explanations on “Digestive System and Nutrition” for Biology Students.
1. Duct leading from parotid gland and opening into vestibule is
(a) Haversian duct
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(b) Stenson’s duct
(c) Wolffian duct
(d) infra-orbital duct.
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Answer and Explanation:
1. (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.
2. Wharton’s duct is associated with
(a) sublingual salivary gland
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(b) parotid salivary gland
(c) submaxillary salivary gland
(d) Brunner’s glands.
Answer and Explanation:
2. (c): The Wharton’s ducts are associated with submaxillary glands that lie at the angles of the lower jaw. These ducts open under the tongue. Ducts of Rivinus are associated with sublingual salivary gland. Stenson’s duct is associated with parotid gland. Brunner’s glands are present in the intestine.
3. Release of pancreatic juice is stimulated by
(a) enterokinase
(b) cholecystokinin
(c) trypsinogen
(d) secretin.
Answer and Explanation:
3. (c): Cholecystokinin (in fact it is cholecystokinin pancreozymin) is a hormone which is secreted by small intestine and stimulates pancreas to secrete and release digestive enzymes in pancreatic juice. Secretin causes the release of bicarbonates in the pancreatic juice. Enterokinase is an enzyme that converts trypsinogen (a proenzyme) into trypsin.
4. Secretin stimulates production of
(a) saliva
(b) gastric juice
(c) bile
(d) pancreatic juice.
Answer and Explanation:
4. (d): Refer answer 3.
5. Emulsification of fat is carried out by
(a) bile pigments
(b) bile salts
(c) HCI
(d) pancreatic juice.
Answer and Explanation:
5. (b): Bile contains no enzyme, and has no chemical action on food. However, it has salts, namely, sodium glycocholate and sodium taurocholate. These salts reduce ; the surface tension of large fat droplets and break them into many small ones. This process is called emulsification. They also form thin coating around tiny fat droplets to keep them from coalescing. This increases lipase action on fats.
6. In man the zymogen or chief cells are mainly found in
(a) cardiac part of stomach
(b) pyloric part of stomach
(c) duodenum
(d) fundic part of stomach.
Answer and Explanation:
6. (d): Zymogen or chief cells are present in the fundic part of stomach. Chief cells are usually basal in location and secrete gastric digestive enzymes as proenzymes or zymogens; pepsinogen and prorennin.
7. Pancreatic juice and hormones of pancreas are produced by
(a) same cells
(b) same cells at different times
(c) statment is wrong
(d) different cells.
Answer and Explanation:
7. (d): The pancreas is a gland organ in the digestive and endocrine systems of vertebrates.
It is both exocrine; (secreting pancreatic juice containing digestive enzymes) and endocrine (producing several important hormones, including insulin, glucagon, and somatostatin). The beta cells produce insulin, alpha cells produce glucagon and delta cells produce somatostatin. There are two main types of exocrine pancreatic cells, responsible for two main classes of secretions. The centroacinar cells produce bicarbonate ions and basophilic cells secrete digestive enzymes.
8. Where is protein digestion accomplished?
(a) stomach
(b) ileum
(c) rectum
(d) duodenum.
Answer and Explanation:
8. (b): Protein digestion starts in the stomach with the action of enzyme pepsin. Then in the duodenum it is carried out by the action of trypsin, chymotrypsin and carboxypeptidases. Then it is done by aminopeptidases and dipeptidases, enterokinases in jejunum and then it ends in the ileum.
9. Pancreas produces
(a) three digestive enzymes and one hormone
(b) three types of digestive enzymes and two hormones
(c) two digestive enzymes and one hormone
(d) three digestive enzymes and no hormone.
Answer and Explanation:
9. (b): Pancreas secretes three types of digestive enzymes trypsinogen, chymotrypsinogen and procarboxypeptidase. These enzymes digest proteins. The two hormones secreted are insulin and glucagon that maintain glucose level in the blood.
10. Brunner’s glands occur in
(a) submucosa of duodenum
(b) submucosa of stomach
(c) mucosa of oesophagus
(d) mucosa of ileum.
Answer and Explanation:
10. (a): The Brunner’s glands are branched tubular glands and are confined to the duodenum. They secrete alkaline watery fluid, a little enzyme and mucus. They open into the crypts of Lieberkuhn.
11. Kupffer’s cells occur in
(a) spleen
(b) kidney
(c) brain
(d) liver.
Answer and Explanation:
11. (d): Kupffer cells are specialized macrophages that dispose of old blood cells and particulate matter. Kupffer cells, named after Karl Wilhelm von Kupffer (1829-1902), are found in the liver, attached to the walls of the sinusoids.
12. Secretion of gastric juice is stopped by
(a) gastrin
(b) pancreozymin
(c) cholecystokinin
(d) enterogastrone.
Answer and Explanation:
12. (d): Enterogastrone is secreted by duodenal epithelium and it slows gastric contractions to delay its emptying and also stops secretion of gastric juice. Gastrin stimulates secretion of gastric juice. Cholecystokinin stimulates release of enzymes in pancreatic juice and release of bile from gall bladder. Cholecystokinin is also known as pancreozymin.
13. Vitamin K is required for
(a) change of prothrombin into thrombin
(b) synthesis of prothrombin
(c) change of fibrinogen to fibrin
(d) formation of thromboplastin.
Answer and Explanation:
13. (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.
14. Most of the fat digestion occurs in
(a) rectum
(b) stomach
(c) duodenum
(d) small intestine.
Answer and Explanation:
14. (d): Fat is largely digested in the small intestine. Bile salts of the bile break down fat droplets into many small ones by reducing the surface tension of fat droplets. This process is called emulsification. This increases lipase action on fat.
15. Which of the following pair is characterised by swollen lips, thick pigmented skin of hands and legs and irritability?
(a) thiamine – beri-beri
(b) protein – kwashiorkor
(c) nicotinamide – pellagra
(d) iodine – goitre.
Answer and Explanation:
15. (c): Pellagra is a disease that occurs due to deficiency of vitamin nicotinamide. Its symptoms are swollen lips, diarrohea, thick pigmented skin of hands and legs and nervous disorder (irritability).
16. Which of the following is correct pairing of site of action and substrate of rennin?
(a) mouth – starch
(b) small intestine – protein
(c) stomach – casein
(d) stomach – fat.
Answer and Explanation:
16. (c): HCI in stomach converts prorennin into active enzyme, rennin. Rennin is active only in infants. It converts milk protein casein into calcium paracaseinate. It is essential for curdling of milk.
17. Prolonged deficiency of nicotinic acid causes
(a) pellagra
(b) xerophthalmia
(c) osteomalacia
(d) anaemia.
Answer and Explanation:
17. (a): Nicotinic acid (niacin) is a part of coenzymes (NAD, NADP) that act as hydrogen acceptors and donors. Its deficiency causes pellagra which is characterized by three D’s such as diarrhoea, dermatitis (skin inflammation) and dementia (nervous disorder). Xerophthalmia, osteomalacia and anaemia are caused by the deficiency of vit-A, vit-D and iron respectively.
18. Which of the following is the function of enterogastrone?
(a) it inhibits the secretion of gastric juice
(b) it stimulates the secretion of digestive juices in the stomach
(c) it stimulates the flow of pancreatic juice
(d) it regulates the flow of bile.
Answer and Explanation:
18. (a): Enterogastrone hormone is released from duodenum and it slows gastric contraction to delay emptying of stomach and stops secretion of gastric juice. Enterogastrone is released when the stomach contents pass into the small intestine.
19. Calcium deficiency in the body occurs in the absence of
(a) vitamin C
(b) vitamin D
(c) vitamin B
(d) vitamin E.
Answer and Explanation:
19. (b): Calcium is an important constituents of bones and teeth. It is present in the blood at a concentration of about 10 mg/100 ml, being maintained at this level by hormones – calcitonin and parathyroid hormone. Ca absorption is enhanced by vitamin D. Thus, deficiency of vitamin D hampers Ca absorption resulting in conditions such as rickets, osteoporosis and osteomalacia. A deficiency of calcium in the blood may lead to tetany.
20. The vitamin C or ascorbic acid prevents
(a) scurvy
(b) antibody synthesis
(c) rickets
(d) pellagra.
Answer and Explanation:
20. (a): Scurvy is characterized by bleeding gums and swollen joints as well as decreased resistance to common cold. This occurs due to the deficiency of vitamin C. Vitamin C is a water soluble vitamin with antioxidant properties that is essential in maintaining healthy connective tissues and the integrity of cell walls. It is essential for the synthesis of collagen. Rickets and pellagra are caused due to deficiency of vitamin D and vitamin B, respectively in the body.
21. A polysaccharide which is synthesized and stored in liver cells is
(a) arabinose
(b) glycogen
(c) lactose
(d) galactose.
Answer and Explanation:
21. (b): The polysaccharide which is synthesized and stored in the liver is glycogen. When there is a need of energy in the body, the glycogen is converted into glucose which is released into the blood to be reached to the target cell.
22. The haemorrhagic disease of new born is caused due to the deficiency of
(a) vitamin K
(b) vitamin B12
(c) vitamin A
(d) vitamin B
Answer and Explanation:
22. (a): Haemorrhagic disease is characterized by profuse bleeding in the newborn. Deficiency of vitamin K, an anti-haemorrhagic factor causes delayed blood clotting in case of injuries. Deficiency of vitamin B12, vitamin A and vitamin B, results in pernicious anaemia; nightblindness and xerophthalmia; and Beri Beri.
23. High cholesterol patients are advised to use
(a) ghee, butter and oils
(b) groundnut oil, margarine and vegetable oils
(c) fatty oil and butter
(d) cheese, dalda and ghee.
Answer and Explanation:
23. (b): Cholesterol is a fat like material (a sterol) present in the blood and most tissues especially nervous tissue. Cholesterol is synthesized in the body from acetate, mainly in the liver and blood concentration is normally 140-300 mg/100 ml. It can exists as a free sterol or esterified with a long chain fatty acid. High cholesterol is harmful for the body. So, high cholesterol patients are advised to take groundnut oil, margarine and vegetable oils, as these contain polyunsaturated fatty acids that contain less cholesterol in them.
24. Pellagra disease is caused by the deficiency of
(a) niacin
(b) tocopherol
(c) riboflavin
(d) folic acid.
Answer and Explanation:
24. (a): Niacin is a vitamin that acts as a part of coenzymes (NAD, NADP) which serve as hydrogen acceptors and donors for many enzymes. Its deficiency in the body causes pellagra which is characterized by dermatitis (skin inflammation), diarrhoea and dementia (nervous disorder). Deficiency of tocopherol (vitamin E) leads to destruction of RBCs. Deficiency of riboflavin (vitamin B2) causes inflammation of eyes, sores on the lips and skin diseases. Folic acid deficiency leads to anaemia and failure of RBCs to mature.
25. Choose the correct enzyme – substrate pair.
(a) carbohydrate – lipase
(b) maltase – lactose
(c) rennin – caesin
(d) protein – amylase.
Answer and Explanation:
25. (c): Rennin is the enzyme that acts on casein which is a milk protein. It is secreted by the gastric glands in an inactive form prorennin which is activated by HCI. Rennin converts caesinogen into calcium paracaesinate in the presence of calcium ions. This ensures that milk remains in the stomach as long as possible. The largest amounts of rennin are present in the stomach of young mammals. Carbohydrate, maltose and protein are acted upon by carbohydrase, maltase and protease respectively.
26. What is common among amylase, rennin and trypsin?
(a) these are produced in stomach
(b) these act at a pH lower than 7
(c) these all are proteins
(d) these all are proteolytic enzymes.
Answer and Explanation:
26. (c): Amylase, rennin and trypsin are enzymes and as all enzymes are proteins so these three are also proteins.
27. If pancreas is removed, the compound which remain undigested is
(a) proteins
(b) carbohydrates
(c) fats
(d) all of these.
Answer and Explanation:
27. (d): Pancreas secretes pancreatic juice that acts on all type of foods. It contains pancreatic amylase for the digestion of carbohydrates; trypsinogen, chymotry- psinogen and procarboxypeptidases for the digestion of proteins, pancreatic lipase for the digestion of fats and nuclease for nucleic acid.
28. Which one of the following vitamins can be synthesized by bacteria inside the gut?
(a) D
(b) K
(c) B
(d) C.
Answer and Explanation:
28. (c): Vitamin B, is synthesized by symbiotic bacteria living inside the gut. This is evidenced by the fact that vitamin B deficiency occurs on taking antibiotics which in addition to killing harmful bacteria also kill useful bacteria forming vitamin B.
29. In vertebrates, lacteals are found in
(a) oesophagous
(b) ear
(c) ileum
(d) ischium.
Answer and Explanation:
29. (c): Ileum is the part of small intestine. Its mucosa is raised into numerous microscopic projections called the villi. The villi contain a minute blind ended lymph vessel lacteals. From the lacteals, the lipoprotein chylomicrons are carried into the blood stream directly via thoracic lymphatic duct.
30. Which one of the factors required for the maturation of erythrocytes?
(a) vitamin B
(b) vitamin C
(c) vitamin D
(d) vitamin A.
Answer and Explanation:
30. (a): Vitamin B12 (also called cyanocobalamine) is essential for the formation and maturation of erythrocytes. Vitamin B12 is manufactured only by micro-organisms and natural sources are entirely of animal origin. One form of vitamin B12 functions as a coenzyme in a number of reactions, including the oxidation of fatty acids and the synthesis of DNA.
It also works in conjunction with folic acid in the synthesis of the amino acid methionine and it is required for normal production of red blood cells. Vitamin A is required for maintenance of epithelia. growth and is a part of visual pigments. Vitamin C play a role in collagen formation. Vitamin D facilitates absorption of calcium and phosphorus by intestine and their retention in the body and deposition in bones.
31. The layer of cells that secrete enamel of tooth is
(a) osteoblast
(b) odontoblast
(c) dentoblast
(d) ameloblast.
Answer and Explanation:
31. (b): Tooth is mainly made of ivory like substance called dentine. In crown part of the tooth, dentine is covered by enamel (hardest substance in the body). Enamel is smooth, white being rich in minerals containing calcium, especially apatite and secreted by cells of ectodermal origin called ameloblasts of the oral epithelium and protects the underlying dentine of the tooth. The pulp cavity of tooth is lined by dentine forming cells called odontoblasts. Osteoblasts are the bone forming cells.
32. Which one of the following is a protein deficiency disease?
(a) kwashiorkar
(b) night blindness
(c) eczema
(d) cirrhosis.
Answer and Explanation:
32. (a): Kwashiorkar is a protein deficiency disease. Its symptoms are underweight, stunted growth, poor brain development, loss of appetite, anaemia, protuding beliy slender legs and bulging eyes. Night blindness is the inability to see in dimlight or at night. It occurs due to deficiency of vitamin A. Eczema is a common itchy skin disease characterized by reddening and vesicle formation. Cirrhosis is a condition in which the liver responds to injury or death of some of its cell by producing interlacing strands of fibrous tissue between which are nodules of regenerating cells.
33. Brunner’s glands are present in
(a) stomach
(b) oesophagus
(c) ileum
(d) duodenum.
Answer and Explanation:
33. (d): Brunner’s glands are branched tubular glands and are confined to the duodenum. They secrete alkaline watery fluid that neutralizes the acidic chyme leaving the stomach, a little enzyme and mucus. They are named after swiss anatomist J.C. von Brunner.
34. Which of the following carries glucose from digestive tract to liver?
(a) pulmonary vein
(b) hepatic artery
(c) hepatic portal vein
(d) none of these.
Answer and Explanation:
34. (c): A system of veins leading from the digestive tract to capillaries in the liver of a vertebrate is known as hepatic portal system. Thus, absorbed products of digestion (except fat) go straight to the liver and not to the heart. Pulmonary vein conveys oxygenated blood from the lungs to the left atrium of the heart. Hepatic artery supply blood to the liver.
35. Which of the following is mismatched?
(a) vitamin A – xerophthalmia
(b) vitamin D – rickets
(c) vitamin K – beri-beri
(d) vitamin C – scurvy.
Answer and Explanation:
35. (c): Deficiency of vitamin K causes haemorrhage, which is characterized by profuse bleeding. Beri beri is caused due to deficiency of vitamin B.
36. To which of the following families do folic acid and pantothenic acid belong?
(a) vitamin C
(b) vitamin B complex
(c) vitamin K
(d) vitamin A.
Answer and Explanation:
36. (b): Vitamin B complex is a group of water soluble vitamins that characteristically serve as components of coenzymes. Plant and many micro-organisms can manufacture B-vitamins but dietary sources arc essential for most animals. Heat and light tend to destroy B vitamins. The vitamin B complex consists of 8 different components – B12. B, (pantothenic acid), B12 nicotinic acid, folic acid, biotin and B12. Pantothenic acid functions as a part of coenzyme A in cell respiration while folic acid functions as part of coenzymes in protein and nucleic acid metabolism.
37. Which part of body secretes the hormone secretin?
(a) stomach
(b) oesophagus
(c) ileum
(d) duodenum.
Answer and Explanation:
37. (d): Secretin hormone is secreted by the duodenal epithelium in response to the presence of hydrochloric acid (HCI). It causes the release of sodium bicarbonate in the pancreatic juice and also steps up secretion of bile in the liver.
38. A person who is eating boiled potato, his food contains the component
(a) cellulose which is digested by cellulase
(b) starch which is not digested
(c) lactose which is not digested
(d) DNA which can be digested by pancreatic DNAase.
Answer and Explanation:
38. (d): Boiled potatoes do not contain lactose; and cellulose which is present is not digested in man as he lacks cellulase. Starch is the major food component which is present in boiled potato and is broken down into maltose and isomaltose due to salivary amylase and is hence digested. DNA is broken down into purines, pyrimidines and sugars by pancreatic nuclease (such as DNAse).
39. In mammals milk is digested by the action of
(a) rennin
(b) amylase
(c) intestinal bacteria
(d) invertase.
Answer and Explanation:
39. (a): Rennin is the enzyme secreted by stomach. It hydrolyzes the soluble milk protein casein into paracasein and whey protein. Paracasein is spontaneously precipitated in the presence of calcium as insoluble calcium paracaseinate, forming coagulated milk. Amylase degrades starch, glycogen and other polysaccharides. Plants contain both a and 3-amylases found in pancreatic juice and also in saliva. Intestinal becteria help by digesting cellulose, invertase acts on sucrose.
40. Which food should be eaten during deficiency of rhodopsin in eyes?
(a) carrot and ripe papayas
(b) guava, banana
(c) mango and potato
(d) none of the above
Answer and Explanation:
40. (a): 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 eye.
41. Essential amino acid is
(a) phenylalanine
(b) glycine
(c) aspartic acid
(d) serine.
Answer and Explanation:
41. (a): Essential amino acids are those amino acids that must be ingested in food for survival as they are not synthesized in (he body. There are 7 essential amino acids. Glycine, aspartic acid and serine are non-essential amino acids as they can be synthesized in the body.
42. Which one of the following is correctly matched?
(a) vitamin E – tocopherol
(b) vitamin D – riboflavin
(c) vitamic B – calciferol
(d) vitamin A – thiamine.
Answer and Explanation:
42. (a): Vitamin E is known as tocopherol. It prevents breakage of red blood cells, may act as an antioxidant, prevents oxidation of certain materials and maintains normal membrane structure. Vitamin D and Vitamin A. are known as calciferol and retinol respectively.
43. Continuous bleeding from an injured part of body is due to deficiency of
(a) vitamin A
(b) vitamin B
(c) vitamin K
(d) vitamin E.
Answer and Explanation:
43. (c): Vitamin K is necessary for the synthesis of prothrombin in the liver. Prothrombin is a factor which is required for blood clotting. Deficiency of vitamin K. leads to slow rate of blood clotting. Vitamin A deficiency leads to night blindness, xerophthalmia and retarded growth. Vitamin B deficiency causes beri-beri, pellagra, anaemia etc. Deficiency of vitamin E leads to destruction of RBCs.
44. Hydrolytic enzymes which act on low pH are called as
(a) proteases
(b) a-amylases
(c) hydrolases
(d) peroxidases.
Answer and Explanation:
44. (a): Stomach has low pH due to secretion of HCI. Protease, an enzyme for digesting protein acts in low pH i.e. in stomach. Amylase is a starch (carbohydrate) digesting enzyme and carbohydrate digestion does not occur in stomach. All digestive enzymes are hydrolases. Peroxidase is an iron containing enzyme, found mainly in plants but also present in leucocytes and milk, that catalyses the dehydrogenation (oxidation) of various substances in the presence of hydrogen peroxide. Amylase is a group of closely related enzymes that degrade starch, glycogen and other polysaccharides. Plants contain both a and p-amylases. Animal possess only a-amylases, found in the pancreatic juice and also in saliva.
45. Stool of a person is whitish grey coloured due to malfunction of which of the following organ?
(a) pancreas
(b) spleen
(c) kidney
(d) liver.
Answer and Explanation:
45. (d): Bilirubin and biliverdin are the pigments present in the bile juice secreted from liver. They provide yellowish brown colour to the stool. So, malfunction of liver leads to appearance of whitish grey stool.
46. During prolonged fastings, in what sequence are the following organic compounds used up by the body?
(a) first carbohydrates, next fats and lastly proteins
(b) first fats, next carbohydrates and lastly proteins
(c) first carbohydrates, next proteins and lastly lipids
(d) first proteins, next lipids and lastly carbohydrates
Answer and Explanation:
46. (a): During prolonged fasting, first carbohydrates are used up then fats and proteins are used at the last. Carbohydrate and fat metabolism can easily produce energy than protein and they follow a more or less simpler pathway to enter into TCA cycle. When all carbohydrates of the body are used up then fats are converted into carbohydrates and when all fats are used up then ultimately proteins of the body are converted into carbohydrates to be used up by the body.
47. Which one of the following pairs is not correctly matched?
(a) vitamin C scurvy
(b) vitamin B2 pellagra
(c) vitamin B12 pernicious anaemia
(d) vitamin B6 beri-beri
Answer and Explanation:
47. (b & d): Among the following options vitamin B12 is not correctly matched with beri-beri and vitamin B2 with pellagra. Vitamin B12 (pyridoxine) performs many functions like protein and amino acid metabolism, production of antibodies for the protection against bacterial disease etc.
However its deficiency is rare and is associated with peripheral neuritis, anaemia, oedema, depression & skin disorders such as cracking at the corner of lips etc. Beri-beri is a disorder arises due to deficiency of vitamin B, (thiamine). Beri beri can be dry type with peripheral neurititis or wet type with cardiac involvement. Deficiency of vitamin B12 (important in cellular oxidation) causes hyporiboflavinosis.
Most common lesion associated with its deficiency is angular stomatitis and not pellagra. Pellagra is characterised by 4 D’s [derinititis (inflammation of skin), diarrhoea, dementia and death and caused by deficiency of vitamin B12 or niacin. Its deficiency also causes black tongue – disease of dogs Scurvy and pernicious anaemia are caused due to deficiency of vitamin C and vitamin B12 respectively.
48. Which one of the following pairs is not correctly matched?
(a) Vitamin B12 – pernicious anaemia
(b) Vitamin B6 – convulsions
(c) Vitamin B, – beri-beri
(d) Vitamin B2 – pellagra.
Answer and Explanation:
48. (d): Deficiency of vitamin B, leads to inflammation of eyes, sores on the lips and skin diseases. Pellagra is caused due to deficiency of nicotinic acid or vitamin B It is characterised by dermatitis (skin inflammation), diarrhoea and dementia (nervous disorder).
49. Duodenum has characteristic Brunner’s gland which secrete two hormones called
(a) kinase, estrogen
(b) secretin, cholecystokinin
(c) prolactin, parathormone
(d) estradiol, progesterone.
Answer and Explanation:
49. (b): Brunner’s glands are present in the duodenum region of small intestine. They secrets two hormones secretin and cholecystokinin. Secretin is secreted by cells in the duodenum when they are exposed to the acidic contents of the emptying stomach. It stimulates the exocrine portion of the pancreas to secrete bicarbonate into the pancreatic fluid (thus neutralizing the acidity of the intestinal contents).
Cholecystokinin (CC’K), a mixture of peptides, is secreted by cells in the duodenum when they are exposed to food. It acts-
• On the gall bladder stimulating it to contract and force its contents of bile into the intestine.
• On the pancreas stimulating the release of pancreatic digestive enzymes into the pancreatic fluid.
CCK, also acts on vagal neurons leading back to the medulla oblongata which give a satiety signal (i.e., “that’s enough food for now”).
50. The richest sources of vitamin B)2 are
(a) goat’s liver and Spirulina
(b) chocolate and green gram
(c) rice and hen’s egg
(d) carrot and chicken’s breast.
Answer and Explanation:
50. (a): Goat’s liver and Spirulina (a bactcrium) are the richest sources of vitamin B,,. Other sources are eggs, meat, fish etc.
51. Which group of three of the following five statements (1 -5) contain all three correct statements regarding beri-beri?
1. a crippling disease prevalent among the native population of sub-Saharan Africa
2. a deficiency disease caused by lack of thiamine (vitamin B,)
3. a nutritional disorder in infants and young children when the diet is persistently deficient in essential protein
4. occurs in those countries where the staple diet is polished rice
5. the symptoms are pain from neuritis, paralysis, muscle wasting, progressive oedema, mental deterioration and finally heart failure.
(a) 2, 4 and 5
(b) 1, 2 and 4
(c) 1, 3 and 5
(d) 2, 3 and 5.
Answer and Explanation:
51. (a): Beri-beri which is caused due to the deficiency of vitamin B,, is characterized by pain from neuritis. Paralysis, muscle wasting, oedema, mental deterioration and finally heart failure. It occurs in those countries (coastal districts of A.P.) where the diet is based on polished rice, which lacks the thiamine-rich seed coat.
52. A patient is generally advised to specially consume more meat, lentils, milk and eggs in diet only when he suffers from
(a) scurvy
(b) kwashiorkar
(c) rickets
(d) anaemia.
Answer and Explanation:
52. (b): Kwashiorkar is caused due to the deficiency of protein and meat, lentils, milk and eggs are rich sources of protein. Scurvy is caused due to deficiency of-vitamin C whose sources are citrus fruit, tomatoes, peppers, leafy green vegetables. Deficiency of vitamin D (sources – milk, egg yolk and liver) leads to rickets. Anaemia is caused due to deficiency of folic acid (sources – yeast, liver, fish, green vegetables) or vitamin B12 (sources – liver, eggs, meat, fish) or iron (egg yolk, spinach).
53. Epithelial cells of the intestine involved in food absorption have on their surface
(a) pinocytic vesicles
(b) microvilli
(c) zymogen granules
(d) phagocytic vesicles.
Answer:
(b) microvilli
54. Secretin and cholecystokinin are digestive hormones. They are secreted in
(a) pyloric stomach
(b) duodenum
(c) ileum
(d) oesophagus.
Answer and Explanation:
54. (b): Refer answer 49.
55. Examination of blood of a person suspected of having anaemia shows large, immature, nucleated erythrocytes without haemoglobin. Supplementing his diet with which of the following is likely to alleviate his symptoms?
(a) iron compounds
(b) thiamine
(c) folic acid and cobalamine
(d) riboflavin
Answer and Explanation:
55. (c): Anaemia is not a disease. It is a symptom of various diseases which may result from excessive blood loss, excessive blood cell destruction, or decreased blood cell formation. Folic acid is a part of coenzymes for protein and nucleic acid metabolism and is essential for growth and formation of RBCs.
Its deficiency leads to anaemia failure of RBCs to mature and sprue. Vitamin B|2 or cyanocobalamin acts as a coenzyme for nucleic acid metabolism and is essential for formation of RBCs and myelin formation. Its deficiency leads to Pernicious (injurious) anaemia and malformation of RBCs.
56. Which one of the following is a fat-soluble vitamin and its related deficiency disease?
(a) Retinol – Xerophthalmia
(b) Cobalamine – Beri-beri
(c) Calciferol – Pellagra
(d) Ascorbic acid – Scurvy.
Answer and Explanation:
56. (a): Retinol (vitamin A) and calciferol are fat soluble vitamins but the pellagra is not the deficient disease of calciferol. Vitamin A cannot be synthesized by mammals and other vertebrates and must be provided in the diet. Green plants contain precursors of the vitamin, notably carotenes, that are converted to vitamin A in the intestinal wall and liver.
The aldehyde derivative of vitamin A, retinal, is a constituent of the visual pigment rhodopsin. Deficiency affects the eyes, causing night blindness, xerophthalmia (dryness and thickening of the cornea), and eventually total blindness.
Pellagra is caused by the deficiency of vitamin B, or nicotinic acid or niacin.
Cobalamine and ascorbic acid (vita’nin C) are water soluble vitamins. They are generally found together in the same foods with the exception of BI: (cobalamine).
The deficient disorders related to cobalamine, vitamin C and calciferol are –
Cobalamine – Pernicious anaemia
Ascorbic acid (vitamin C) – Scurvy
Calciferol (vitamin D) – Rickets (in children) and osteomalacia in adults.
Beri-beri is caused by the deficiency of vitamin B1 (Thiamine).
57. Which one of the following mammalian cells is not capable of metabolising glucose to carbon- dioxide aerobically?
(a) unstriated muscle cells
(b) liver cells
(c) red blood cells
(d) white blood cells.
Answer and Explanation:
57. (c): Yeast have highly adaptable metabolic patterns. Under fully aerobic conditions, they are able to metabolize glucose to carbon dioxide and water. This requires a process of aerobic metabolism known as the citric acid cycle, which occurs in the mitochondria. Under anaerobic condition, yeast are still able to use glucose as an energy source.
However, in this case, the end products are ethanol and carbon dioxide, and there is no net oxidation of the glucose. This type of metabolism is called fermentation and occurs entirely in the cytoplasm. Red blood cells are also known as RBCs or erythrocytes.
Erythrocytes in mammals are anucleate when mature, meaning that they lack a cell nucleus and thus have no DNA. Mammalian erythrocytes also lose their other organelles including their mitochondria and produce energy by fermentation, via glycolysis of glucose followed by lactic acid production. Furthermore, red cells do not have an insulin receptor and thus glucose uptake is not regulated by insulin. As a result of the lack of nucleus and organelles, the cells cannot produce new structural or repair proteins or enzymes and their lifespan is limited.