CDS (I) 2023 GK Q4: Which one of the following statements regarding bile

Q: What is the answer to CDS (I) 2023 GK Q4?

A. Correct — A, Bile contains enzymes for digestion of lipids. Bile is made by the liver, stored and concentrated in the gall bladder, and it carries no digestive enzyme of any kind. By composition it is roughly 97 to 98 per cent water, with about 0.7 per cent bile salts, 0.2 per cent bilirubin, half a per cent of fats including cholesterol and lecithin, and inorganic salts. What the bile salts do is mechanical rather than chemical: each ion has a water-loving face and a fat-loving one, so they gather round large fat droplets and break them into a fine suspension, multiplying the surface an enzyme can work on. The enzyme itself, pancreatic lipase, arrives separately from the pancreas. Statement (a) therefore describes bile wrongly, which is what a 'not correct' item wants you to find.

CDS (I) 2023 General Knowledge · Question 4 of 120

Question text verified against the official CDS question paper.

Which one of the following statements regarding bile secreted by liver is not correct?

(a)Bile contains enzymes for digestion of lipids.
(b)Bile facilitates emulsification of fats.
(c)Bile neutralizes the acidic pH of the food coming from stomach.
(d)Bile makes the pH of the food alkaline and facilitates action of pancreatic enzymes.

Answer

Why

Correct — A, Bile contains enzymes for digestion of lipids. Bile is made by the liver, stored and concentrated in the gall bladder, and it carries no digestive enzyme of any kind. By composition it is roughly 97 to 98 per cent water, with about 0.7 per cent bile salts, 0.2 per cent bilirubin, half a per cent of fats including cholesterol and lecithin, and inorganic salts. What the bile salts do is mechanical rather than chemical: each ion has a water-loving face and a fat-loving one, so they gather round large fat droplets and break them into a fine suspension, multiplying the surface an enzyme can work on. The enzyme itself, pancreatic lipase, arrives separately from the pancreas. Statement (a) therefore describes bile wrongly, which is what a 'not correct' item wants you to find.

Why the others are wrong

(b)Bile facilitates emulsification of fats. — True, and it is bile's central job. Bile salts are amphipathic, so they surround fat droplets and split them into much smaller ones — a physical action that gives lipase far more surface to attack. A true statement cannot be the answer here.
(c)Bile neutralizes the acidic pH of the food coming from stomach. — True. Food leaves the stomach soaked in hydrochloric acid, and bile is alkaline; one of its stated functions is neutralising that acid as the chyme enters the duodenum.
(d)Bile makes the pH of the food alkaline and facilitates action of pancreatic enzymes. — True, and it is the reason the neutralising matters. Pancreatic enzymes work in a slightly alkaline medium, so the acid arriving from the stomach must be countered before they can act.

Concept

Bile is a greenish-yellow alkaline fluid secreted continuously by the liver, held in the gall bladder between meals and released into the duodenum through the bile duct. Its working components are the bile salts, made from cholesterol, together with the pigment bilirubin left over from the breakdown of haemoglobin. Bile does two jobs in digestion — it makes the intestinal contents alkaline, and it emulsifies fat. Neither job involves an enzyme; the enzymes of the small intestine come from the pancreas and from the intestinal wall.

The item is built around a real and common confusion: bile obviously has something to do with fat digestion, so it feels natural to say it digests fat. It does not. Separating what bile does from what pancreatic juice does is the whole point — bile disperses, lipase cuts. A useful check is that the same duct system delivers both to the duodenum, which is why they are so often merged in memory. Note also that the paper's phrase 'acidic pH of the food' is loose; what arrives from the stomach is chyme, partly digested food mixed with gastric acid.

Key facts

Bile is about 97 to 98 per cent water, with roughly 0.7 per cent bile salts, 0.2 per cent bilirubin and half a per cent of fats including cholesterol and lecithin.
Bile salts are amphipathic — water-loving on one face, fat-loving on the other — so they gather round fat droplets and break them up.
Bile is alkaline and neutralises the acid chyme leaving the stomach, giving pancreatic enzymes the slightly alkaline medium they need.
The enzyme that actually digests fat is pancreatic lipase, secreted by the pancreas, not by the liver.
Bilirubin in bile is a waste pigment from the breakdown of haemoglobin, and it gives faeces their colour.

Bile and pancreatic juice — two secretions, two different jobs

Bile — where it is made→Secreted by the liver, stored and concentrated in the gall bladder, released into the duodenum.

Bile — what it contains→Mostly water, plus bile salts, bilirubin, cholesterol and inorganic salts. No digestive enzymes.

Bile — what it does→Makes the intestinal contents alkaline and emulsifies fat into fine droplets. Both actions are physical or chemical, not enzymatic.

Pancreatic juice — what it contains→Lipase for fats, amylase for starch, trypsin and other proteases for protein.

Why the pairing matters→Bile makes the droplets small; lipase then digests them. Statement (a) hands bile the pancreas's job.

The exam tests the division of labour: bile prepares the fat, pancreatic lipase digests it.

Study next

The human alimentary canal and which secretion enters at each pointPancreatic juice — lipase, amylase and trypsin, and the conditions each needsEmulsification as a physical process, and why surface area governs enzyme actionThe liver's other roles — bile production, detoxification, storage of glycogenBilirubin, jaundice, and what a blocked bile duct does

Common traps

Assuming that because bile helps with fat, it must contain a fat-digesting enzyme.
Mixing up bile with pancreatic juice because both empty into the duodenum through the same opening.
Overlooking the 'not correct' wording and picking the most familiar true statement.

Either as this odd-one-out on bile's properties, or as a straight item asking which secretion contains no enzyme, or which organ supplies lipase.

Related PYQs

UPSC_2006_GS1_Q152006Open & attempt →

Consider the following statements with reference to the human body: 1. The common bile duct releases its contents into the stomach. 2. The pancreatic duct releases its contents into the duodenum. Which of the statements given above is/are correct?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Answer(b) 2 only

The plumbing behind this item. Bile and pancreatic juice both arrive in the duodenum, not the stomach, and keeping the two secretions apart in the mind is what stops a student handing bile the pancreas's enzymes.

NDA_GAT_2022_II_Q772022Open & attempt →

The digestion of fat in human intestine is performed by

(a) trypsin
(b) bile and lipase
(c) bile and amylase
(d) bile and pepsin

Answer(b) bile and lipase

The same division of labour asked positively. Fat needs two things — bile to break the droplets up and lipase to digest them — and the pairing shows why bile alone, without an enzyme, would not be enough.

Practice

practice — not a real PYQ
The enzyme responsible for the digestion of fats in the human small intestine is secreted by which one of the following organs?
- (a)Liver
- (b)Gall bladder
- (c)Pancreas
- (d)Stomach
Answer(c) Pancreas — pancreatic lipase does the digesting; the liver's bile only emulsifies the fat so that the lipase can reach it.
practice — not a real PYQ
Bile secreted by the liver is stored in which one of the following?
- (a)Duodenum
- (b)Gall bladder
- (c)Pancreas
- (d)Spleen
Answer(b) Gall bladder — bile is stored and concentrated there between meals and released into the duodenum when fatty food arrives.