Biology · Science General

Human Digestive System

1,953 Questions

The human digestive system explores the breakdown of biomacromolecules, covering organs from the stomach to the small intestine. It involves physiological processes like chyme movement, pH levels, and nutrient absorption in the gut. These fundamental biology concepts are regularly featured in medical and general science competitive exams.

Small intestine functionsBiomacromolecule breakdownStomach and digestionIntestinal bacteria

Human Digestive System Questions

Multiple choice biology digestion and absorption digestion in small intestine digestive glands and their secretions alimentary canal

Match the digestive juices with the enzymes given under. Choose the choice which gives the correct combination of the alphabets of the two columns.

   List I (Digestive juices)    List II (Enzymes)
 A  Saliva p  Maltase
 B Gastric juice  q  Trypsinogen
 C  Pancreatic juice r  Ptyalin
 D  Intestinal juice s   Pepsin
    t   Cellulase

  1. A- r, B- s, C- q, D- p

  2. A- s, B- r, C- p, D- t

  3. A- r, B- t, C- p, D- q

  4. A- r, B- s, C- p, D- t
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Salivary juice contains starch splitting enzyme amylase. The amylase of saliva is called as ptyalin. Pepsin is the major proteolytic enzyme of stomach. Pepsin is secreted as a proenzyme pepsinogen and is activated to pepsin on exposure to acid in stomach. Trypsin is a component of pancreatic juice where it is present as trypsinogen. Trypsinogen is activated to trypsin on exposure to enterokinase. The intestinal juice contains a number of disaccharidases like maltase, lactase, sucrase for splitting disaccharides into monosaccharides, which can be readily absorbed.

Multiple choice biology digestion and absorption digestion in small intestine digestive glands and their secretions alimentary canal

How many enzymes in the list given below infound in pancreatic juice?
Enterokinase, Chymotrypsin, Aminopeptidase, Pepsin, Lactase, Rennin, Carboxypeptidase, Nuclease, Nucleotidase & Elastase:-

  1. Six

  2. Three

  3. Five

  4. Four
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Trypsinogen, chymotrypsinogen, elastase, carboxypeptidase, nuclease are the enzymes secreted by the pancreas.

Multiple choice biology digestion and absorption digestion in small intestine digestive glands and their secretions alimentary canal

Emulsification of fats by bile takes place in  

  1. Duodenum

  2. Liver

  3. Stomach

  4. Intestine
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Secretion and synthesis of bile is the main function of liver. Bile is yellowish-green, alkaline fluid. In bile juice, bile salts, sodium carbonate, glycolate, taurocholate, bile pigments, cholesterol, lecithin etc. are present. Bile salts help in emulsification of fats in small intestine. It mainly act at the duodenum part of the small intestine.

Multiple choice biology digestion and absorption digestion in small intestine digestive glands and their secretions alimentary canal

Which one of the following is the correct matching of the site of action on the given substrate, the enzyme acting upon it and the end product?

  1. Small intestine : $\rightarrow $ Proteins Pepsin Amino acids
  2. Stomach : $\rightarrow $ Fats Lipase Micelles
  3. Duodemum : $\rightarrow $ Triglycerides Trypsin Monoglycerides
  4. Small intestine : $\rightarrow $ Starch Amylase Disaccharide (Maltose)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Amylase digests complex starch (polysaccharide) molecules into smaller, simpler maltose (disaccharide) molecules. 

Multiple choice biology digestion and absorption digestion in small intestine digestive glands and their secretions alimentary canal

Lactase is found in

  1. Saliva

  2. Bile

  3. Pancreatic juice

  4. Intestinal juice
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Lactase is an enzyme produced by the small intestine, found in the digestive system of humans. It is essential to complete the digestion of whole milk. Lactase breaks down lactose, a simple sugar which gives milk its sweetness. 

Multiple choice biology digestion and absorption digestion in small intestine digestive glands and their secretions alimentary canal

Fats in the stomach is inhibited. This inhibition is due to

  1. Presence of fat

  2. Non stimulation of vagus nerve

  3. Slow digestion of fat

  4. Release of enterogastron
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  •  In the digestive environment, proteins, carbohydrates are initially attacked by enzymes produced by your salivary glands and stomach. And then it attacks fats.
  • However, effective enzymatic breakdown of fats requires emulsification by bile acids, a process that does not occur until fats leave your stomach and enter your small intestine. Hence, Fats in the stomach is inhibited. This inhibition is due to the slow digestion of fat. So, the correct answer is 'Slow
    digestion of fat'.

Multiple choice biology digestion and absorption digestion in small intestine digestive glands and their secretions alimentary canal

Assertion  :  The main part of carbohydrate digestion
                      takes place in small intestine.

Reason    :    Here pancreatic amylase converts
                       carbohydrates into lactose


  1. If both the assertion and the reason are true and the reason

    is a correct explanation of the assertion

  2. If both the assertion and reason are true but the reason is

    not a correct explanation of the assertion

  3. If the assertion is true but the reason is false

  4. If both the assertion and reason are false

  5. If the assertion is false but reason is true
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In small intestine Pancreatic amylase converts starch and dextrose into maltoses and small intestine is main site for digestion of carbohydrates.

Multiple choice biology digestion and absorption digestion in small intestine digestive glands and their secretions alimentary canal

Fatty acid and glycerol are first taken up from alimentary
canal by

  1. villi

  2. Blood capillaries

  3. Hepatic portal vein

  4. Lymph vessels
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Generally, fatty acids upto a chain length of 10 carbon atom are primarily absorbed through the blood capillaries, but those with higher chain length through lymphatic route (lymph vessels).

Multiple choice biology digestion and absorption digestion in small intestine digestive glands and their secretions alimentary canal

Pancreatic juice and bile are poured through

  1. A common area into duodenum

  2. Two distinct ducts into duodenum

  3. A common duct into ileum

  4. Two distinct ducts into ileum
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pancreatic juice and bile both empty into the duodenum. They typically join to form the common bile duct or hepatopancreatic duct before entering the duodenum at the major duodenal papilla.