Exams › NEET › Biology › Digestion and Absorption
68 questions with worked solutions.
Q1. Pepsin acts in
Answer: Acidic medium
Pepsin is a stomach protease that becomes active in low pH conditions. Its optimal activity is in an acidic medium, which helps it digest proteins efficiently.
Q2. lleum is characterised by the presence of
Answer: Peyer's patches and villi
The ileum is distinguished by Peyer’s patches, which are aggregated lymphoid nodules, and it also has villi for absorption. Brunner’s glands are found in the duodenum, and taeniae coli are features of the large intestine.
Q3. Identify the correct statement with reference to human digestive system.
Answer: Ileum is a highly coiled part
The ileum is the final and highly coiled segment of the small intestine. The other statements are incorrect because serosa is the outermost layer, the appendix arises from the caecum, and the ileum opens into the large intestine, not the small intestine.
Q4. Which cells of 'Crypts of Lieberkuhn' secrete antibacterial lysozyme?
Answer: Paneth cells
Paneth cells in the crypts of Lieberkühn secrete lysozyme, defensins, and other antimicrobial substances to help control gut bacteria. The other options are liver, gastric, or endocrine-related cells and do not perform this function.
Q5. Which of the following statements is not correct?
Answer: Brunner’s glands are present in the submucosa of stomach and secrete pepsinogen
Brunner’s glands are located in the submucosa of the duodenum, where they secrete alkaline mucus, not pepsinogen. The other statements correctly pair the structure with its location and secretion.
Q6. Which of the following guards the opening of hepatopancreatic duct into the duodenum?
Answer: Sphincter of Oddi
The sphincter of Oddi is the smooth muscle valve that surrounds the opening of the hepatopancreatic duct into the duodenum. It controls the release of bile and pancreatic juice into the small intestine.
Answer: epiglottis
The epiglottis acts like a lid over the trachea during swallowing, preventing food from entering the airway. If it doesn’t move properly, food can trigger coughing by irritating the windpipe.
Answer: Small intestine: Starch Disaccharide (Maltose)
In the small intestine, pancreatic amylase acts on starch and produces maltose as an intermediate product. The other options mismatch either the site, substrate, or end product of digestion.
Q9. If for some reason goblet cells are non-functional, this will adversely affect:
Answer: smooth movement of food down the intestine
Goblet cells secrete mucus, which lubricates and protects the lining of the intestine. Without this mucus, intestinal contents would not move as smoothly, so passage of food is impaired.
Q10. Stool of a person is whitish grey coloured due to malfunction of which of the following organ?
Answer: Liver
The liver produces bile, which contains pigments that give stool its normal brown color after digestion. If the liver is malfunctioning, bile flow may be reduced or blocked, causing whitish-grey stools.
Q11. The food having fully undergone mechanical and chemical digestion inside the stomach, is called:
Answer: Chyme
Chyme is the partially digested, semi-fluid mixture formed in the stomach after mechanical churning and chemical digestion. Bolus is the chewed food before swallowing, while chyle is a milky fluid formed later in the small intestine during fat absorption.
Q12. Emulsification of fat is carried out by:
Answer: Bile salts
Bile salts emulsify fats by dispersing them into small droplets, which increases the surface area available for lipase action. Bile pigments do not emulsify fat, and HCl or pancreatic juice do not perform this detergent-like role.
Q13. In man the zymogen or chief cells are mainly found in:
Answer: Fundic part of stomach
Zymogen (chief) cells secrete pepsinogen and are located mainly in the fundic glands of the stomach. The fundic part is the main region for gastric secretion, unlike the pyloric and cardiac regions.
Q14. Duct leading from parotid gland and opening into vestibule is
Answer: Stensen’s duct
The parotid gland drains saliva through Stensen’s duct, which opens into the oral vestibule near the upper second molar. The other options are unrelated anatomical ducts.
Q15. The enzyme enterokinase helps in conversion of
Answer: trypsinogen into trypsin
Enterokinase (enteropeptidase) is a brush-border enzyme of the duodenum that converts trypsinogen into trypsin. Trypsin then activates several other pancreatic zymogens, making this the key initiating step.
Q16. Wharton’s duct is associated with
Answer: Submaxillary salivary gland
Wharton’s duct is the excretory duct of the submandibular (submaxillary) salivary gland. It carries saliva into the floor of the mouth, unlike Stensen’s duct, which belongs to the parotid gland.
Q17. Match the following structures with their respective location in organs:
Answer: (D) Brunner’s glands - (i) Pancreas
Brunner’s glands are mucus-secreting glands located in the submucosa of the duodenum, not the pancreas. The other pairings are mismatched because Crypts of Lieberkühn are in the intestine, Glisson’s capsule is associated with the liver, and Islets of Langerhans are in the pancreas.
Answer: Goblet cells
Goblet cells secrete mucus that coats the gastrointestinal lining and shields it from digestive enzymes and mechanical damage. Chief cells make pepsinogen, oxyntic cells secrete acid and intrinsic factor, and duodenal cells are not the main mucus-secreting protective cells.
Q19. In the stomach, gastric acid is secreted by the
Answer: parietal cells
Parietal cells in the stomach lining secrete hydrochloric acid, which creates the acidic environment needed for digestion. Gastrin-secreting cells release a hormone, and peptic cells mainly secrete digestive enzymes.
Q20. Gastric juice of infants contains:
Answer: pepsinogen, lipase, rennin
Infant gastric juice contains pepsinogen, lipase, and rennin. Rennin helps curdle milk, while pepsinogen is the inactive precursor of pepsin and lipase aids fat digestion.