Digestive System

1. Tigers have a shorter small intestine compared to cows. The length of

Tigers have a shorter small intestine compared to cows. The length of the small intestine differs in various animals depending on the

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availability of water in their habitat.
size of their mouth cavity.
kind of habitats where they live.
kind of food they eat.
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UPSC CISF-AC-EXE – 2020
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Tigers are carnivores and cows are herbivores. The length of the small intestine in animals is primarily adapted to the type of food they eat. Carnivores eat meat, which is relatively easy to digest and absorb, thus requiring a shorter digestive tract. Herbivores eat plant material, which is rich in cellulose and requires a longer, more complex digestive process, often involving fermentation by symbiotic microorganisms. A longer small intestine provides more surface area and time for the digestion and absorption of nutrients from plant matter.
The digestive system, including the length of the small intestine, is adapted to the diet of the animal. Herbivores have longer intestines than carnivores due to the difficulty in digesting plant cellulose.
The digestion of cellulose in herbivores often occurs in specialized chambers (like the rumen in cows) or in the hindgut, requiring a slower passage rate and a larger surface area for absorption, which is facilitated by a longer small intestine and overall digestive tract.

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2. For the digestion of carbohydrate, protein and fat, enzymes such as am

For the digestion of carbohydrate, protein and fat, enzymes such as amylase, trypsin and lipase are required. It is secreted into the duodenum through :

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Bile
Plasma
Lymph
Pancreatic juice
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UPSC CAPF – 2023
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Amylase (for carbohydrates), trypsin (for proteins), and lipase (for fats) are major digestive enzymes secreted by the pancreas. The pancreas releases these enzymes, along with other components, as pancreatic juice. Pancreatic juice is secreted into the duodenum, the first part of the small intestine, through the pancreatic duct to facilitate the digestion of food entering from the stomach.
The pancreas produces and secretes a suite of digestive enzymes (amylase, lipase, proteases like trypsin and chymotrypsin) via the pancreatic duct into the duodenum.
Bile is produced by the liver and stored in the gallbladder, then secreted into the duodenum. Bile aids in fat digestion by emulsification, but it does not contain the enzymes amylase, trypsin, or lipase. Plasma and lymph are components of the circulatory and lymphatic systems, not involved in secreting digestive enzymes into the digestive tract.

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3. Which one of the following statements regarding digestion is correct?

Which one of the following statements regarding digestion is correct?

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Fat present in the food is digested by trypsin and chymotrypsin.
Starch of food is digested by lipases.
Fat of food is digested by lipases.
Nucleic acid is digested by amylases.
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UPSC CAPF – 2018
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Digestion involves enzymatic breakdown of macromolecules in food. Different types of enzymes are specific for different types of molecules. Fats (lipids, primarily triglycerides) are digested by enzymes called lipases. For example, pancreatic lipase is the main enzyme responsible for fat digestion in the small intestine, breaking triglycerides down into fatty acids and glycerol.
Let’s examine the other options:
A) Trypsin and chymotrypsin are proteases, enzymes that digest proteins into smaller peptides and amino acids. They do not digest fats.
B) Starch is a complex carbohydrate. Carbohydrates like starch are digested by amylases (e.g., salivary amylase, pancreatic amylase) into smaller sugars. Lipases digest fats.
D) Nucleic acids (DNA and RNA) are digested by nucleases into nucleotides. Amylases digest carbohydrates.
Thus, the correct statement is that fat of food is digested by lipases.
Specific enzymes are required to digest different classes of macromolecules: Lipases for fats, Amylases for carbohydrates (like starch), Proteases for proteins, and Nucleases for nucleic acids.
Bile salts, produced by the liver and stored in the gallbladder, are also important for fat digestion. They emulsify large fat globules into smaller droplets, increasing the surface area available for lipases to act upon.

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4. Use of tamarind juice as a part of our meal helps

Use of tamarind juice as a part of our meal helps

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to prevent tooth decay
to take care of excess fluoride in drinking water
for easy digestion of food
to increase the strength of bones
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UPSC CAPF – 2012
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The correct answer is C) for easy digestion of food.
Tamarind is known for its sour taste due to the presence of tartaric acid and other organic acids. Including acidic or sour elements in a meal is traditionally believed to stimulate the secretion of digestive enzymes and juices, thereby aiding in the breakdown and digestion of food, particularly fats and proteins.
Option A is incorrect; acidic substances can contribute to tooth erosion and decay. Option B is not a known effect of tamarind consumption. Option D is incorrect; bone strength is primarily related to calcium, phosphorus, and vitamin D intake, not tamarind.

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5. Which one among the following causes stomach pain in human body?

Which one among the following causes stomach pain in human body?

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Base
Acid
Salt
Bacterium
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UPSC CAPF – 2012
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The correct answer is B) Acid.
The human stomach contains hydrochloric acid, which is essential for digestion. However, an excess production of stomach acid (hyperacidity) can lead to irritation of the stomach lining or esophagus, causing symptoms like heartburn, acid reflux, and stomach pain.
While bacteria like Helicobacter pylori can cause stomach ulcers and gastritis leading to pain, among the direct chemical options provided, acid (specifically, excessive stomach acid) is a common and direct cause of stomach pain symptoms like burning and aching. Bases and salts are not typically the primary direct causes of stomach pain in this context, although some substances containing them might cause irritation.

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6. The protein-digesting enzyme secreted by the stomach wall in case of m

The protein-digesting enzyme secreted by the stomach wall in case of mammals is called

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chitinase
amylase
pepsin
trypsin
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UPSC NDA-2 – 2022
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The correct answer is pepsin.
The stomach lining secretes gastric juice containing hydrochloric acid and enzymes. The primary protein-digesting enzyme in the stomach is pepsin. Pepsin is secreted in an inactive precursor form called pepsinogen, which is converted to active pepsin by the acidic environment created by hydrochloric acid.
Amylase (e.g., salivary amylase) digests carbohydrates. Trypsin is a protein-digesting enzyme secreted by the pancreas and active in the small intestine. Chitinase digests chitin, a polysaccharide found in the exoskeletons of insects and fungi.

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7. The digestion of fat in human intestine is performed by

The digestion of fat in human intestine is performed by

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trypsin
bile and lipase
bile and amylase
bile and pepsin
This question was previously asked in
UPSC NDA-2 – 2022
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The digestion of fat in the human intestine is primarily performed by enzymes called lipases, which break down fats into fatty acids and glycerol. Bile, produced by the liver and stored in the gallbladder, is released into the intestine to emulsify large fat globules into smaller droplets. This emulsification increases the surface area available for lipase action, making the digestion more efficient.
Fat digestion requires both the emulsifying action of bile and the enzymatic action of lipase.
Trypsin and pepsin are enzymes that digest proteins. Amylase is an enzyme that digests carbohydrates (starch). Without bile, the digestion of fats by lipase would be very slow and incomplete due to the large size of fat globules. The major fat-digesting enzyme in the intestine is pancreatic lipase.

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8. What is the total number of chambers in the stomach of domestic animal

What is the total number of chambers in the stomach of domestic animals like cattle, buffalo, goat and sheep ?

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Four
Two
One
Three
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UPSC NDA-2 – 2021
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The correct answer is A) Four.
Domestic animals like cattle, buffalo, goat, and sheep are ruminants. Ruminants possess a unique digestive system featuring a four-chambered stomach.
The four chambers are the rumen, reticulum, omasum, and abomasum. The rumen is the largest chamber where microbial fermentation of plant material occurs. The abomasum is the true glandular stomach, similar to that of monogastric animals.

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9. The acidic semidigested food coming out of the stomach is neutralized

The acidic semidigested food coming out of the stomach is neutralized by

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pancreatic juice
duodenal secretion
large intestine secretion
bile juice
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UPSC NDA-2 – 2018
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The acidic semidigested food (chyme) coming out of the stomach into the duodenum is neutralized primarily by the bicarbonate ions present in pancreatic juice. Bile juice and duodenal secretions also contribute bicarbonate.
– Stomach contents are highly acidic (pH 1.5-3.5) due to hydrochloric acid.
– Enzymes in the small intestine, particularly pancreatic enzymes, function optimally in a slightly alkaline environment (pH 7-8).
– Pancreatic juice is rich in bicarbonate ions (HCO₃⁻), which effectively neutralize the acidity of the chyme entering the duodenum, raising the pH to the optimal range for enzyme activity.
Bile juice, produced by the liver, is also alkaline (pH 7.6-8.6) due to bicarbonate ions absorbed from the blood and secreted by bile duct cells, and it also helps in neutralization, in addition to its primary role in fat emulsification. Duodenal glands (Brunner’s glands) also secrete alkaline mucus containing bicarbonate, providing protection and lubrication. However, pancreatic juice is generally considered the main source of bicarbonate for bulk neutralization in the duodenum.

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10. In the human digestive system, which one among the following is the ro

In the human digestive system, which one among the following is the role of the pancreas ?

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Secretion of surfactants to break up lipid droplets
Storage and regulated release of bile
Secretion of lipase, amylase and protease
Neutralizing stomach acids
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UPSC NDA-1 – 2024
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The primary role of the pancreas in the human digestive system, among the given options, is the secretion of lipase, amylase, and protease. This corresponds to option C.
The exocrine function of the pancreas involves producing pancreatic juice containing essential digestive enzymes like pancreatic amylase (breaks down carbohydrates), pancreatic lipase (breaks down fats), and proteases such as trypsin and chymotrypsin (break down proteins). This juice is secreted into the small intestine.
The pancreas also has an endocrine function, secreting hormones like insulin and glucagon into the bloodstream to regulate blood sugar. While the pancreas also secretes bicarbonate to neutralize stomach acid in the duodenum (related to option D), option C specifically lists the major digestive enzymes it produces, which is a core digestive role. Option A describes the role of bile salts, and option B describes the role of the gallbladder.

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