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

Most of the fat digestion occurs in

  1. Rectum

  2. Stomach

  3. Duodenum

  4. Small intestine
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Digestion of fat begins in duodenum with the help of pancreatic lipase but cannot be completed there because of its small size. Further it is component of small intestine. In infants some digestion occurs in stomach.

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

A complete digestive juice is

  1. Bile

  2. Pancreatic juice

  3. Succus entericus

  4. Gastric juice
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Succus entericus, also known as intestinal juice, contains a wide variety of enzymes including disaccharidases, dipeptidases, lipases, and nucleosidases that complete the final stages of carbohydrate, protein, and fat digestion. Thus, it is referred to as a complete digestive juice. Pancreatic juice contains many enzymes too, but succus entericus finalizes all nutrient breakdowns.

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

Most of the digestion of lipids in humans takes place in

  1. mouth

  2. stomach

  3. small intestine

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

  • Most lipids that you consume in your diet are fats. Some digestion occurs in your mouth and the stomach but mostly takes place in the small intestine. The purpose of the small intestine is to finish digestion and absorb nutrients. The small intestine is where most chemical digestion takes place. 
  • Many of the digestive enzymes that act in the small intestine are secreted by the pancreas and liver and enter the small intestine via the pancreatic duct. Hence, most of the digestion of lipids in humans takes place in the small intestine.
So, the correct answer is 'small intestine'.

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

Which of the following associations is incorrect?

  1. Protein - trypsin

  2. Starch - amylase

  3. Fat - lipase

  4. Maltose - pepsin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

  • Trypsin is produced in the pancreas as an inactive protease trypsinogen. It is a protease found in the digestive system of many vertebrates, where it hydrolyses protein.
  • Amylase is a protein produced by the pancreas and by glands in and around mouth and throat. It helps you break down carbohydrates and starches into sugar.
  • Lipase is a protein produced by the pancreas. It is an enzyme that catalyses the hydrolysis of fats.
  • Pepsin is an endopeptidase produced in the stomach. It breaks down proteins into smaller peptides. Hence, the incorrect association is maltose-pepsin.
So, the correct answer is 'Maltose-pepsin'.

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

Digestive enzymes are released by pancreas and bile is released by liver in response to the hormone :-

  1. insulin

  2. zymogen

  3. secretin

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

CCK is in the duodenum and stimulates the release of digestive enzymes in the pancreas and stimulates the emptying of bile in the gallbladder. This hormone is secreted in response to the fat in the chyme

So, the correct answer is 'Cholecystokinin'

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

Which one of the following statements is true regarding digestion and absorption of food in humans?

  1. Oxyntic cells in our stomach secrete the proenzyme pepsinogen
  2. Fructose and amino acids are absorbed through intestinal mucosa with the help of carrier ions like ${K}^{+}$

  3. Chylomicrons are small lipoprotein particles that are transported from the intestine through blood capillaries to various tissues.

  4. About 60% of starch is hydrolysed by salivary amylase in our mouth
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the intestinal mucosal cells, after absorption, the triglycerides and cholesterol are re-esterified to form chylomicrons. The chylomicrons in turn are secreted into intestinal lymph, enter the blood stream through the thoracic duct and bind to the wall of capillaries in adipose and skeletal tissue.

So, option C is the correct answer.

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

Which one of the following statements is true regarding digestion and absorption of food on humans?

  1. Fructose and amino acids are absorbed through intestinal mucosa with the help of carrier ions like ${Na}^{+}$

  2. Chylomicrons are small lipoprotein particles that are transported from intestine into blood capillaries

  3. About 60% of starch in hydrolysed by salivary amylase in our mouth

  4. Oxyntic cells in our stomach secrete the proenzyme pepsinogen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Digestion is the process where complex material in the food is broken down to simple nutrients and molecules so that they can be absorbed and circulated in the body. 
  • The digestion of the food starts in the buccal cavity of the organism where the enzyme amylase is secreted. This enzyme is used for the digestion of the starch present in the food. Though much of the starch is digested in the mouth it is divided in disaccharide units of carbohydrates which will be further digested in intestine. 
  • The food from the buccal cavity is taken to the stomach via oesophagus where the food is stored for about 3 to 4 hours and mixed with the hydrochloric acid which is secreted by the oxyntic cell present in the mucosa wall of the stomach. This will give the food a acidic pH which is necessary for the activation of the pepsin enzyme which are there for digestion of proteins to peptides. 
  • This acidic chyme of the stomach is to be transported for further digestion in the intestine where it is mixed with the alkaline secretion released from the liver and pancreas. 
  • In intestine the food components such as carbohydrates, proteins, lipids etc are digested to small absorbable molecules. 
  • The carbohydrates are digested to monosaccharides glucose, fructose, galactose, proteins are broken down to amino acids and lipids are reduced to small fat globules called microns. 
  • Some of these components are already present in the cell fo the body surrounding the digestive track. So for the transport of molecules ion transporters are used sach as sodium ion transporter, etc. 
  • Glucose is easily digested compared to other molecules of monosaccharides as it is easily soluble in water. Monosaccharides such as fructose and amino acid units are transported to the blood stream along with the sodium ions that are transportedby the sodium ion transporter. 
  • Fat globules are transported by the lacteal cells that are present in the intestine mucosa of the intestine. Chylomicrons are also used to transport fat to liver and adipose tissue where it can be stored. 
  • Therfore for the following question option A and C are correct. 
Multiple choice biology digestion and absorption digestion in small intestine digestive glands and their secretions alimentary canal

Rennin and lactase, the enzymes required to digest milk, disappear in the human body by the age of

  1. Five

  2. Three

  3. Two

  4. Eight
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Rennin is an aspartic endopeptidase belonging to MEROPS A1 family. It is produced by newborn ruminant animals in the lining of the abomasum to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption. It is widely used in the production of cheese. Lactase is an enzyme produced by many organisms.  Lactase can be purchased as a food supplement, and is added to milk to produce "lactose-free" milk products. Lactase is the enzymes that splits lactose (milk sugar) into glucose and galactose. The enzymes necessary to break down and digest milk (rennin and lactase) are all gone by the age of three in most humans. 

So the correct option is 'three'.

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

Which of the following processes is helped by bile salts?

  1. Nucleic acid $\overset{Nuclease}{\rightarrow}$ Nucleotides $\overset{Nucleotidase}{\rightarrow}$ Nucleosides $\overset{Nucleosidase}{\rightarrow}$ Sugars + bases
  2. Sucrose $\overset{Sucrase}{\rightarrow}$ Glucose + Fructose
  3. Fats $\overset{Lipase}{\rightarrow}$ Diglyceides $\overset{Lipase}{\rightarrow}$ Monoglycerides
  4. Proteins, peptones, proteoses $\xrightarrow[Carboxypeptidase]{Trypsin/Chymotrypsin}$ Dipeptides
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The correct answer is (c).

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

The digestion of cellulose in rabbit and other herbivorous mammals takes place in

  1. Vermiform appendix

  2. Colon

  3. Caecum

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

Hindgut fermentation is a digestive process seen in monogastric herbivores, animals with a simple, single-chambered stomach. Cellulose is digested with the aid of symbiotic bacteria. The microbial fermentation occurs in the digestive organs that follow the small intestine: the large intestine and caecum.

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

Sucrase is an enzyme found in:-

  1. saliva

  2. gastric juice

  3. intestinal juice

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

Sucrase enzymes are located on the brush border of the small intestine. The enzymes catalyze the hydrolysis of sucrose to fructose and glucose. The sucrase enzyme invertase, which occurs more commonly in plants, also hydrolyzes sucrose but by a different mechanism

So, the correct option is 'Intestinal juice'

Multiple choice evs more about organ system introduction to excretory system structures and functions related to the excretory system introduction to excretion

Which of the following is NOT a physical process of digestion?

  1. Deglutition

  2. Churning

  3. Peristalsis

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

(A) Deglutition is the process of swallowing the masticated food.

(B) Churning is the process in which the stomach mixes its digestive enzyme with food.
(C) Peristalsis is a wave-like muscle contraction that helps in the food movement in different digestive organs like oesophagus. 
(D) Emulsification is the process of mixing of bile with fat to change it into micelles.
So, the correct option is 'Emulsification'.