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 bio-chemistry coordination in life processes digestive system - organs process of digestion coordination in the process of digestion

Proteolytic enzymes do not corrode lining of alimentary canal is

  1. They are secreted in inactive form

  2. Lining layer of alimentary canal does not contain protein

  3. The enzymes are not capable of digesting fat

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Proteolytic enzymes like pepsin are secreted as inactive zymogens (pepsinogen) to prevent them from digesting the proteins that make up the stomach wall itself.

Multiple choice bio-chemistry coordination in life processes digestive system - organs process of digestion coordination in the process of digestion

What will happen if secretion of parietal cells of gastric glands is blocked?

  1. Gastric juice is deficient of pepsinogen

  2. Gastric juice is deficient of chymosin

  3. Deficiency of HCl leads to nonconversion of inactive pepsinogen into active pepsin

  4. Nonrelease of enterokinase from duodenal mucosa and non-conversion of trypsinogen into trypsin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Gastric glands are numerous microscopic tubular glands formed by the epithelium of stomach. The parietal cells (oxyntic cells) are large and most numerous on the sidewalls of gastric glands. They secrete hydrochloric acid and castle intrinsic factor. The peptic cells (zymogen) cells of gastric glands secrete gastric digestive enzymes as proenzymes-pepsinogen and prorennin and a small amount of gastric amylase and gastric lipase. The hydrochloric acid maintains a strongly acidic pH of about 1.5 to 2.5 in the stomach. HCl converts pepsinogen and prorennin to pepsin and rennin respectively. 

So, the correct answer is 'Deficiency of HCl leads to nonconversion of inactive pepsinogen into active pepsin'.

Multiple choice bio-chemistry coordination in life processes digestive system - organs process of digestion coordination in the process of digestion


Which of the following correctly describes the oesophagus?

  1. Food moves through the oesophagus under voluntary control

  2. Food enters the oesophagus from the pyloric region of the stomach

  3. It allows the passage of chyme

  4. It is a collapsible muscular tube extending from pharynx to stomach
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • The oesophagus is a long, muscular tube that connects your mouth to your stomach. It's around 25cm (10 in) long in adults. 
  • When you swallow food, the walls of the oesophagus squeeze together (contract).
  •  This moves the food down the oesophagus to the stomach. Hence, the oesophagus is a collapsible muscular tube extending from pharynx to stomach.
So, the correct answer is ' collapsible muscular tube extending from pharynx to stomach'. 
Multiple choice bio-chemistry coordination in life processes digestive system - organs process of digestion coordination in the process of digestion


The acidic region of gastrointestinal tract is

  1. mouth

  2. large intestine

  3. small intestine

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

  • Parietal cells in the stomach secrete roughly two litres of acid a day in the form of hydrochloric acid. 
  • The acid in the stomach functions to kill bacteria, and to help digestion by solubilizing food. 
  • The acid is also important to maintain the optimal pH (between 1.8-3.5) for the function of the digestive enzyme pepsin. Hence, the acidic region of the gastrointestinal tract is the stomach.
So, the correct answer is 'stomach'.

Multiple choice bio-chemistry coordination in life processes digestive system - organs process of digestion coordination in the process of digestion

Which one of the following pairs of food components in humans reaches the stomach totally undigested? 

  1. Starch and fat

  2. Fat and cellulose

  3. Starch and cellulose

  4. Protein and starch
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • In humans starch is digested in the buccopharyngeal cavity, protein is digested in the stomach and fat in the small intestine.
  • In Humans cellulose is not digested because in humans cellulose-digesting enzyme is absent.
  • In Humans fats are digested in the stomach and the cellusose digesting enzyme is absent The pairs of food components in humans reaches the stomach totally undigested are fats and cellulose.
  • So, the correct answer is 'Fat and cellulose'.
Multiple choice bio-chemistry coordination in life processes digestive system - organs process of digestion coordination in the process of digestion

Which of the following statements is incorrect?

  1. Brunner's glands are submucosal.

  2. Irregular folds of gastric mucosa are rugae.

  3. Glisson's capsule is the connective tissue sheath of hepatic lobule.

  4. Mesothelium or serosa lies in close proximity to the circular layer of muscularis.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The correct answer is (d).

Multiple choice bio-chemistry coordination in life processes digestive system - organs process of digestion coordination in the process of digestion

Which of the following is a part of your digestive system?

  1. Stomach

  2. Teeth

  3. Rectum

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Digestion starts from the mouth and ends at large intestine. When the food enters mouth (ingestion), it is broken into small pieces by the teeth and acted upon by salivary amylase. Then it travels down the oesophagus to the stomach, where digestive enzymes from the pancreas, gall bladder, liver and duodenum further digest it. Assimilation of nutrients occurs at small intestine and absorption of water and other substances happen at the large intestine before it is egested or excreted. Thus, the correct answer is option D.

Multiple choice bio-chemistry coordination in life processes digestive system - organs process of digestion coordination in the process of digestion

Which type of cells are the part of tubular  glands of the stomach epithelium?
A. Parietal cells
B. Peptic cells
C. Zymogen cells 
D. Oxyntic cells 

  1. D only

  2. A & D

  3. A,B & C

  4. A,B,C & D
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is option (D) 

Parietal cells (also known as oxyntic cells) are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor. 
Peptic cells are also known as zymogen cells releases pepsinogen and chymosin. It means all cells given in the option belongs to stomach epithelium and the part of tubular gland.

Multiple choice bio-chemistry coordination in life processes digestive system - organs process of digestion coordination in the process of digestion

Which of the following are chiefly digested in the stomach?

  1. Protein

  2. Carbohydrate

  3. Lipids

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

Digestion is a  process where the food is broken down by the mechanical and chemical process. Digestion begins at the mouth where the only carbohydrate is digested due to the presence of salivary amylase. Food then moves to the stomach through oesophagus where the gastric juice is secreted by the stomach wall which contains pepsin for protein digestion HCl and mucus. It digestion the complex form of protein into the simple form. Maximum protein is digested in the stomach.

Therefore, the correct answer is option A.

Multiple choice bio-chemistry coordination in life processes digestive system - organs process of digestion coordination in the process of digestion

Germs entering the body through food are mainly killed in the region of alimentary canal where pH may reach the level

  1. 2

  2. 7

  3. 10

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

Digestion in the human body is a complex process where pH of the digestive tract plays a crucial role. pH level in the region of pharynx and mouth is controlled by the saliva and is maintained at about 6.8. However, in the stomach, the gastric acid lowers the pH to 1-3 making it highly acidic. This acidic condition activates the digestive enzyme pepsinogen and converts it into pepsin for protein digestion and kills the pathogenic bacteria. Therefore, the correct answer is option A.

Multiple choice bio-chemistry digestion digestive system - organs process of digestion coordination in the process of digestion

The opening of the stomach in duodenum is regulated by  

  1. Sphineter of Oddi

  2. Pyloric sphincter

  3. Gastro-oesophageal

  4. Ileo-caeeal valve
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A. Sphincter of Oddi is the opening of the hepatopancreatic duct into duodenum.

B. Pyloric sphincter is found between the duodenum and posterior stomach. It regulates the opening of duodenum into stomach.
C. Gastro-oesophageal sphincter is found between the oesophagus and stomach.
D. Ileo-caecal valve is present between ileum of small intestine and caecum of large intestine.
So, the correct answer is 'Pyloric sphincter'.