Tiêu đề Ex- 3. Digestion and absorption (Q-A-Sol).docx.pdf ✅

8 DIGESTION AND ABSORPTION EXERCISE – 3 : Achiever’s Section Digestive System 1. Alimentary Canal 1. Match the following: A B i. Tooth is embedded inside socket of jaw-bone A. Diphyodont ii. Temporary teeth replaced by a set of permanent teeth B. Monophyodont iii. Different types of teeth C. Thecodont iv. Only one set of teeth in a lifetime D. Heterodont (a) i-A, ii-C, iii-B, iv-D (b) i-B, ii-D, iii-A, iv-C (c) i-C, ii-A, iii-D, iv-B (d) i-D, ii-C, iii-B, iv-A Ans. (c) Sol. Thecodont is a condition in which the tooth is embedded inside the socket of the jaw-bone. Diphyodont is a condition in which a temporary set of teeth is replaced by a set of permanent teeth. Different types of teeth in jaw sockets are called heterodont type dentition. Only a single set of teeth in the lifetime is called monophyodont dentition. 2. The number of teeth that grow twice in human life is (a) 4 (b) 12 (c) 20 (d) 28 Ans. (c) Sol. In humans, their primary set of 20 deciduous teeth are completely replaced by permanent adult teeth up to the age of 18 years or so. Teeth replaced by permanent teeth are 2 incisors, 1 canine, and 2 molars in each half of dental curvature. Thus, making it to a total of 5 X4 = 20 teeth. Children do not have premolars. The two premolars and the last molar are the teeth in each half of the jaws, which comes only once and only in adults. 3. Diastema refers to (a) gap between the teeth (b) gap between tongue and teeth (c) cilliary cells on elementary wall (d) cell lining along pharynx Ans. (a) Sol. Diastema refers to a gap between teeth. It may be a natural, inherited character or due to some type of gum disease. 4. Read the following statements and find out the incorrect statement. I. Small intestine is distinguished into three regions- a ‘U’shaped duodenum, a long coiled middle portion jejunum and a highly coiled ileum. II. Oesophagus opens into the cardiac part of stomach. III. Arrangement of teeth in each half of upper and lower jaw is represented by dental formula. IV. Rectum is a small sac which hosts some symbiotic micro-organisms. (a) I and IV (b) II and IV (c) II and III (d) I and III Ans. (a) Sol. The statements I and IV are incorrect. The correct statements should be – Small intestine is distinguished into three regions ‘C' shaped duodenum, a long coiled middle portion jejunum and highly coiled ileum. Caecum is a small sac which hosts some symbiotic micro-organisms. 5. Match column-I with column-II and select the correct option from the codes given below. Column-I (Sphincter) Column-II (Location) A. Gastro-oesophageal sphincter (i) Opening of hepatopancreatic ampulla into duodenum B. Cardiac sphincter (ii) Between duodenum and posterior stomach C. Sphincter of Oddi (iii) Controls the passage of food into the stomach D. Ileo-caecal sphincter (iv) Between oesophagus and anterior stomach
9 DIGESTION AND ABSORPTION E. Pyloric sphincter (v) Between small intestine and large intestine (a) A-(iii), B-(ii), C-(iv), D-(i), E-(v) (b) A-(iii), B-(v), C-(i), D-(iv), E-(iii) (c) A-(iii), B-(iv), C-(i), D-(v), E-(ii) (d) A-(iv), B-(iii), C-(i), D-(ii), E-(v) Ans. (c) Sol. The correct match of sphincters with their respective locations should be – Gastro-oesophageal sphincter - Controls the passage food into the stomach. Cardiac sphincter - between the oesophagus and anterior stomach. Sphincter of Oddi - opening of hepatopancreatic ampulla into duodenum Ileocaecal sphincter - between the small intestine and large intestine. Pyloric sphincter - between duodenum and posterior stomach. 6. Fill in the blanks: 1. The opening of the stomach in duodenum is regulated by...a... 2. Opening of the common hepatopancreatic duct is guarded by a structure called ...b... 3. The structure which prevents the back flow of faecal matter is called ...c... 4. A muscular structure that regulates the opening of oesophagus into stomach is called ...d... (a) a-sphincter of Oddi, b- pyloric sphincter, c-gastro-oesophagal sphincter, d-ileo-caecal valve (b) a-pyloric sphincter, b- sphincter of Oddi, c-ileo-caecal valve, d-gastro-oesophageal sphincter (c) c-sphincter of Oddi, b- pyloric sphincter, a-gastro-esophageal sphincter, d-ileo-caecal valve (d) d-sphincter of Oddi, c- pyloric sphincter, b-gastro-oesophagal sphincter, a-ileo-caecal valve Ans. (b) Sol. The pyloric sphincter is located between the posterior stomach and duodenum. It prevents the passage of food particles present in the stomach to pass into the duodenum until proper mixing with gastric juice is done. Sphincter of Oddi is the muscular valve that controls the flow of bile and pancreatic juice into the duodenum. The Ileocecal valve separates the small intestine and large intestine. It prevents the reflux of colonic content into the ileum. Gastroesophageal sphincter is present at the junction of the esophagus and stomach. It is also called cardiac sphincter 7. Which of the following control the peristaltic movements of alimentary canal. (a) local neural mechanisms (b) CNS (c) Hormones (d) all of these Ans. (d) Sol. The muscular activities of different parts of the alimentary canal are moderated by neural mechanisms which are local, (generally influencing a small region of the alimentary canal) or through the central nervous system. Hormones, which are the chemical messengers, are also involved in the regulation of rhythmic contraction and relaxation of the alimentary canal i.e., peristalsis. 8. Assertion: Human beings have two sets of teeth during their life. Reason: Human beings have thecodont dentition. (a) if both assertion and reason are true, and the reason is the correct explanation of the assertion. (b) if assertion and reason are true, but the reason is not the correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. Ans. (b) Sol. Majority of mammals including human beings possess two sets of teeth during their life, a set of temporary milk or deciduous teeth replaced by a set of permanent or adult teeth. This type of dentition is called diphyodont. Human beings also have thecodont dentition, i.e., teeth are embedded in the sockets o the jaw bones. 9. Assertion: Mucosal epithelium of gut has goblet cells which secrete mucus. Reason: The mucus in the gastric and pancreatic juice protects the mucosa from excoriation by acidic secretion. (a) if both assertion and reason are true, and the reason is the correct explanation of the assertion. (b) if assertion and reason are true, but the reason is not the correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. Ans. (b)
10 DIGESTION AND ABSORPTION Sol. Mucosal epithelium has goblet cells which secrete mucus that helps in lubrication. The mucus in gastric and pancreatic secretion plays an important role in lubrication and protection of mucosa epithelium from excoriation by highly acidic HCl. 2. Digestive Glands 10. Match column-I with column-II and select the correct option from the codes given below. Column-I Column-II A. Goblet cells (i) Antibacterial agent B. Lysozyme (ii) Mucus C. Saliva (iii) HCl D. Oxyntic cells (iv) Sublingual gland (a) A-(iii), B-(i), C-(iv), D-(ii) (b) A-(i), B-(iii), C-(iv), D-(ii) (c) A-(ii), B-(iii), C-(i), D-(iv) (d) A-(ii), B-(i), C-(iv), D-(iii) Ans. (d) Sol. The main function of goblet cells is to secrete mucus. Lysozyme is one of the most abundant antibacterial agents in the human body. The sublingual gland is a type of salivary gland which secretes saliva which contain mucous as a major constituent. Oxyntic cells mainly secrete hydrochloric acid (HCl) for maintaining the acidic pH of the stomach. 11. Match column-I with column-II and select the correct option from the codes given below. Column-I Column-II A. Kupffer cells (i) Islets of Langerhans B. β-cells (ii) Liver C. Oxyntic cells (iii) Thyroid gland D. Paneth cells (iv) Stomach (v) Small intestine (a) A-(iv), B-(v), C-(i), D-(ii) (b) A-(iii), B-(i), C-(iv), D-(ii) (c) A-(iv), B-(v), C-(iii), D-(i) (d) A-(ii), B-(i), C-(iv), D-(v) Ans. (d) Sol. Kupffer cells are macrophages present in liver sinusoids. β-cells are endocrine cells present in Islets of Langerhans in the pancreas. Oxyntic cells are present in the stomach mucosa whereas Paneth cells are present in the small intestinal mucosa. 12. Read the following statement and find out the correct statement A. The pancreas is a compound (both exocrine and endocrine) elongated organ situated between the limbs of the ‘C’shaped duodenum. B. The exocrine portion secretes an alkaline pancreatic juice containing enzymes and endocrine portion secretes hormones, insulin and glucagon. C. Mucus in saliva helps in lubricating and adhering the masticated food particles into a bolus. D. The bolus is then conveyed into the pharynx and then into the oesophagus by peristalsis. (a) A, B (b) B, C (c) C, D (d) All of the above Ans. (d) Sol. All the statements are correct. The pancreas is a compound (both exocrine and endocrine), an elongated organ situated between the limbs of the ‘C’ shaped Duodenum. The exocrine portion secretes an alkaline pancreatic juice containing enzymes and endocrine portion secretes hormones, insulin and glucagon. Mucus in saliva helps in lubricating and adhering the masticated food particles into a bolus. The bolus is then conveyed into the pharynx and then into the oesophagus by peristalsis. 13. In the given figure, organs have been labelled as (a), (b) and (c). Find the organ whose secretion contains lipid- digesting enzyme: (a) (a) (b) (c) (c) (a) and (c) (d) (b) Ans. (b) Sol.
11 DIGESTION AND ABSORPTION The pancreas is an organ which contains lipid digestive enzymes (lipases). It is a heterocrine gland because it has two regions: one for the endocrine function and the other for the exocrine function. Digestion of Food 14. Consider the following four statements and select the correct option stating which ones are true (T) and which ones are false (F). (i) The stomach has the lowest pH (ii) The liver contains lipid emulsifier (iii) Large intestine secretes many enzymes (iv)All proteases function in the lumen of small Intestine (i) (ii) (iii) (iv) (a) T F T F (b) F T F T (c) F F T T (d) T T F F Ans. (d) Sol. Statement (i) is true as hydrochloric acid is released in the stomach hence the pH here is the lowest. Statement (ii) is also true as bile, which is a lipid emulsifier, is present in the liver. Statement (iii) is false as the large intestine doesn't secrete enzymes. Instead, the small intestine secretes multiple enzymes. Statement (iv) is also false as proteases are also present and function in the lumen of the stomach and not only in the lumen of the small intestine. 15. Arrange the correct sequence of enzyme which act on food in different regions of alimentary canal. 1. Pepsin 2. Ptylin 3. Dipeptidases 4. Carboxypeptidases (a) 1 3 2 4 (b) 2 1 4 3 (c) 1 4 3 2 (d) 2 1 3 4 Ans. (b) Sol. Ptyalin is secreted in the oral cavity by the salivary gland. Pepsin is secreted by peptic cells in the form of proenzyme pepsinogen in the stomach. Carboxypeptidase is secreted by the pancreas in the form of a proenzyme, procarboxypeptidase into the duodenum. Dipeptidase is secreted by brush border cells of the intestinal mucosa and is present in intestinal juice or succus entericus. 16. Which one leaves human stomach at the earliest? (a) Fat (b) Protein (c) Carbohydrate (d) Beer Ans. (d) Sol. Only some chemicals, medicines and alcohol are absorbed in the oropharyngeal cavity. In the stomach, absorption of water, some salts, alcohol and glucose take place, complete absorption of alcohol takes place in the stomach. Thus, carbohydrates, proteins and fats can stay in the digestive system for complete digestion and when broken down completely in the small intestine then only they will be absorbed in the intestine but beer will not be digested in the alimentary canal and directly absorbed in the stomach. 17. Match the type of cells listed under Column I and their secretion given under column II. Choose the answer which gives the correct combination of the alphabets of the two columns: Column I (Type of cells) Column II (Secretions) A. Peptic cells p Mucus B. Oxyntic cells q Alkaline fluid C. Goblet cells r Pro-enzymes s HCl (a) A = q, B = p, C = s (b) A = s, B = r, C = q (c) A = s, B = p, C = q (d) A = r, B = s, C = p Ans. (d) Sol. Peptic cells release proenzymes such as pepsinogen and this pepsinogen is converted into active pepsin when it comes in contact with hydrochloric acid. Oxyntic cells mainly secrete hydrochloric acid. The main function of goblet cells is to secrete mucus. 18. What will happen if the secretion of parietal cells of the gastric glands is blocked with an inhibitor?