40. Villi are present in which part of the body?
[RRB Group D (28 Sep 2022, Shift 3)]
- (a) Eye
- (b) Kidney
- (c) Liver
- (d) Small intestine
Answer: (d) Small intestine
Explanation: Villi are minute finger-like outgrowths of the intestinal mucosa. They greatly expand surface area and contain blood capillaries and lymphatic lacteals, permitting efficient uptake of digested nutrients. They are characteristic of the small intestine rather than the listed organs.
39. Where are carbohydrates, proteins, and fats completely digested?
[RRB Group D (17 Sep 2022, Shift 3)]
- (a) Stomach
- (b) Small intestine
- (c) Rectum
- (d) Large intestine
Answer: (b) Small intestine
Explanation: The small intestine receives bile and pancreatic secretions and produces brush-border digestive enzymes. Together these processes complete breakdown of the major dietary macromolecules. The stomach begins substantial protein digestion, while the large intestine primarily absorbs water and salts.
38. Salivary amylase helps in the digestion of which substance?
[RRB Group D (15 Sep 2022, Shift 3)]
- (a) Lipids
- (b) Proteins
- (c) Starch
- (d) Cellulose
Answer: (c) Starch
Explanation: Ptyalin, the amylase in saliva, attacks starch molecules and yields smaller carbohydrates, including maltose and dextrins. Its action begins in the mouth but diminishes when gastric acidity inactivates the enzyme. Human saliva does not contain cellulase.
37. What are the small finger-like intestinal projections that increase absorption called?
[RRB Group D (13 Sep 2022, Shift 2)]
- (a) Sphincters
- (b) Glands
- (c) Cilia
- (d) Villi
Answer: (d) Villi
Explanation: Intestinal villi project from the inner lining of the small intestine. Their thin epithelium and rich vascular and lymphatic supply support nutrient absorption. Together with microvilli they enlarge the area across which digested molecules enter the body.
36. What is the effect of bile salts during digestion?
[RRB Group D (13 Sep 2022, Shift 2)]
- (a) They divide large fat globules into small droplets
- (b) They activate enzymes that digest proteins
- (c) They themselves contain digestive lipase
- (d) They directly hydrolyse fats into fatty acids
Answer: (a) They divide large fat globules into small droplets
Explanation: Bile salts emulsify large fat globules without chemically hydrolysing triglycerides. Dividing fat into smaller droplets exposes a greater surface area to pancreatic lipase. This cooperation makes fat digestion and subsequent absorption substantially more efficient.
35. Which is NOT a function of bile juice?
[RRB Group D (09 Sep 2022, Shift 2)]
- (a) Supporting pancreatic enzyme efficiency
- (b) Dividing large fat globules
- (c) Providing conditions suitable for pancreatic enzymes
- (d) Providing a protein-digesting enzyme
Answer: (d) Providing a protein-digesting enzyme
Explanation: Bile contains bile salts and other components but no protein-digesting enzyme. Its key digestive function is emulsification of dietary lipids, along with supporting intestinal conditions. Pancreatic proteases, not bile, perform the hydrolysis of food proteins.
34. Which terminal part of the alimentary canal expels solid waste?
[RRB Group D (06 Sep 2022, Shift 2)]
- (a) Large intestine
- (b) Small intestine
- (c) Appendix
- (d) Anus
Answer: (d) Anus
Explanation: The anus is the terminal opening through which faeces are expelled during defecation. The colon absorbs water and forms faeces, whereas the rectum temporarily stores them. Anal sphincter muscles help regulate their eventual passage outside the body.
33. Which villus features aid nutrient absorption:
(i) thin walls,
(ii) large area,
(iii) food-passing pores,
(iv) rich blood capillaries?
[RRB Group D (26 Aug 2022, Shift 3)]
- (a) Only (i) and (iii)
- (b) (i), (ii) and (iv)
- (c) Only (i)
- (d) Only (ii) and (iii)
Answer: (b) (i), (ii) and (iv)
Explanation: Villi have a thin epithelial covering, a greatly increased surface area, and extensive capillaries that take up water-soluble nutrients. Their lacteals absorb most dietary lipid products. Large pores allowing whole food particles through are not a normal absorptive feature.
32. Which carbohydrate cannot be digested by human digestive enzymes?
[WBCS Mains 2021, Paper-IV (exam held May 2022)]
- (a) Starch
- (b) Cellulose
- (c) Glycogen
- (d) Glucose
Answer: (b) Cellulose
Explanation: Humans lack cellulase, the enzyme required to split the beta-1,4 bonds of cellulose. Cellulose therefore functions mainly as dietary fibre, although intestinal microbes may ferment some of it. Starch and glycogen can be hydrolysed by amylases and other enzymes.
31. Which enzyme pair does not work well in an acidic environment?
[UPSC CDS-I, General Knowledge (10 Apr 2022)]
- (a) Trypsin and pepsin
- (b) Chymotrypsin and pepsin
- (c) Trypsin and amylase
- (d) Pepsin and amylase
Answer: (c) Trypsin and amylase
Explanation: Trypsin prefers alkaline intestinal conditions, and pancreatic or salivary amylase acts best near neutral pH. Pepsin is adapted to the strongly acidic stomach. Thus, trypsin and amylase are the pair least suited to highly acidic conditions.
