30. Fat digestion in the human intestine involves which pair?
[UPSC NDA-II (2022)]
- (a) Trypsin alone
- (b) Bile and lipase
- (c) Bile and amylase
- (d) Bile and pepsin
Answer: (b) Bile and lipase
Explanation: Bile salts emulsify fats into small droplets. Pancreatic lipase then catalyses the breakdown of triglycerides into smaller lipid products for absorption. Trypsin and pepsin digest proteins, while amylase targets carbohydrate starch rather than dietary fats.
29. Which organ produces bile juice?
[RRB NTPC CBT-I (21 Mar 2021, Shift 2)]
- (a) Liver
- (b) Heart
- (c) Brain
- (d) Kidney
Answer: (a) Liver
Explanation: Bile is synthesised continuously by liver cells and carried through bile ducts. The gallbladder stores and concentrates it until release into the duodenum. Bile salts assist lipid emulsification, but the liver does not produce bile-digesting enzymes.
28. Which statement about the stomach is NOT correct?
[RRB NTPC CBT-I (06 Apr 2021, Shift 1)]
- (a) Mucus protects its lining
- (b) Gastric glands release acid, pepsin and mucus
- (c) It receives the liver and pancreas secretions for digestion
- (d) HCl provides a medium for pepsin
Answer: (c) It receives the liver and pancreas secretions for digestion
Explanation: The stomach secretes gastric juice, containing acid, mucus, and pepsin-related secretions. Bile and pancreatic juice enter the duodenum of the small intestine, not the stomach. The stomach chiefly starts protein digestion and mechanically mixes food.
27. Which digestive organ has a shape resembling the letter J?
[RRB NTPC CBT-I (13 Mar 2021, Shift 2)]
- (a) Liver
- (b) Mouth
- (c) Stomach
- (d) Intestine
Answer: (c) Stomach
Explanation: The stomach is a muscular, roughly J-shaped sac connected to the oesophagus and duodenum. It stores, churns, and mixes food with gastric secretions. Its acidic juice promotes the first major stage of protein digestion.
26. In which organ is hydrochloric acid secreted?
[MPPSC State Service Preliminary Examination (2021)]
- (a) Intestine
- (b) Liver
- (c) Stomach
- (d) Pancreas
Answer: (c) Stomach
Explanation: Hydrochloric acid originates from parietal cells of the stomach lining. It produces the low pH that activates pepsinogen and favours pepsin action. Bile from the liver and alkaline pancreatic secretions have different roles after food enters the duodenum.
25. In which organ does the digestion of proteins chiefly begin?
[UPPSC PCS Preliminary Examination (2020)]
- (a) Liver
- (b) Mouth
- (c) Small intestine
- (d) Stomach
Answer: (d) Stomach
Explanation: Pepsin begins major chemical digestion of proteins in the strongly acidic stomach. The enzyme is formed by activation of pepsinogen. Pancreatic trypsin and other proteases later continue protein breakdown in the small intestine, where absorption becomes possible.
24. Which organ is an important source of the digestive enzyme lipase?
[66th BPSC Preliminary Re-examination (2020)]
- (a) Kidney
- (b) Pancreas
- (c) Liver
- (d) Heart
Answer: (b) Pancreas
Explanation: The exocrine pancreas releases pancreatic lipase into the duodenum. This enzyme hydrolyses dietary triglycerides after bile salts emulsify fats. The liver produces bile, not pancreatic lipase. Smaller contributions to fat digestion also occur elsewhere in the digestive tract.
23. Digestion of which food component starts in the human buccal cavity?
[MPPSC State Service Preliminary Examination (2019)]
- (a) Protein
- (b) Fat
- (c) Carbohydrate
- (d) None of these
Answer: (c) Carbohydrate
Explanation: Salivary amylase in the mouth initiates breakdown of starch, which is a carbohydrate. Chewing assists by increasing contact with saliva. Substantial protein digestion begins in the stomach, and most fat digestion takes place in the small intestine.
22. Which calcium compound makes up most of tooth enamel?
[UPSC NDA-I (2019)]
- (a) Calcium carbonate
- (b) Calcium sulphate
- (c) Calcium hydroxide
- (d) Calcium phosphate
Answer: (d) Calcium phosphate
Explanation: Tooth enamel is rich in hydroxyapatite, a crystalline calcium phosphate mineral. Its dense mineral structure makes enamel the hardest tissue in the human body. Enamel protects the crowns of teeth as they cut, crush, and grind food.
21. What chiefly neutralises acidic chyme entering the duodenum?
[UPSC NDA-II (2018)]
- (a) Pancreatic juice
- (b) Duodenal secretion
- (c) Large intestine secretion
- (d) Bile juice
Answer: (a) Pancreatic juice
Explanation: The pancreas releases bicarbonate-rich fluid into the duodenum, neutralising hydrochloric acid carried from the stomach. The resulting higher pH supports pancreatic enzymes. Bile also contributes to the intestinal environment, but bicarbonate is the major chemical neutraliser.
