Digestive System MCQ Quiz - Objective Question with Answer for Digestive System - Download Free PDF

The correct answer is option A i.e. Acidic.

• The stomach is a muscular hollow organ.
• It takes in food from the esophagus (gullet or food pipe), mixes it, breaks it down, and then passes it on to the small intestine in small portions.
• The stomach stores the food for 4-5 hours.
• The food mixes thoroughly with the acidic gastric juice of the stomach by the churning movements of its muscular wall and is called the chyme. 
• Gastric juice is made up of digestive enzymes, hydrochloric acid and other substances that are important for absorbing nutrients – about 3 to 4 liters of gastric juice are produced per day.
• The hydrochloric acid in the gastric juice breaks down the food and the digestive enzymes split up the proteins.
• The acidic gastric juice also kills bacteria. 

The correct answer is Mucous neck cells, Peptic or Chief cells and Parietal or Oxyntic cells.

• The stomach is located in the upper left quadrant of the abdomen and receives food from the oesophagus.
• The internal most layer of the stomach is called mucosal lining and it carries the human gastric glands. It is also called gastric mucosa.
• There are a total of four types of cells that make up the gastric glands which are-
  • Mucous cells
  • Parietal cells
  • Chief cells
  • Endocrine cells
• The secretions of the exocrine gastric glands - composed of the mucous, parietal, and chief cells - make up the gastric juice.
• The endocrine cells secrete the hormone gastrin, directly into the bloodstream and are not a part of the gastric juice.

The correct answer is lysosomes.

Key Points

• Lysosomes
  • These are membrane bound vesicular structures formed by the process of packaging in the golgi apparatus.
  • The isolated lysosomal vesicles have been found to be very rich in almost all types of hydrolytic enzymes (hydrolases – lipases, proteases, carbohydrases) optimally active at the acidic pH.
    • These enzymes are capable of digesting carbohydrates, proteins, lipids, and nucleic acids.

Important Points

• Vacuoles
  • The vacuole is the membrane-bound space found in the cytoplasm.
  • It contains water, sap, excretory product and other materials not useful for the cell.
  • The vacuole is bound by a single membrane called tonoplast.
  • In plant cells, the vacuoles can occupy up to 90% of the volume of the cell.
• Mitochondria
  • It is sausage-shaped or cylindrical having a diameter of 0.2-1.0µm (average 0.5µm) and length 1.0-4.1µm.
  • It is called the powerhouse of the cell.
  • Each mitochondrion is a double membrane-bound structure with the outer membrane and the inner membrane dividing its lumen distinctly into two aqueous compartments.
    • The outer compartment and the inner compartment.
    • The inner compartment is filled with a dense homogeneous substance called the matrix.
    • The outer membrane forms the continuous limiting boundary of the organelle.
• Ribosomes
  • Ribosomes are made up of RNA and proteins. 
  • The ribosomes, which are present in all active cells, are the sites of protein manufacture.
  • In prokaryotes, ribosomes are associated with the plasma membrane of the cell.

The correct answer is Statement I and II are correct.

Key Points

• Statement I: The small intestine is the primary site for nutrient absorption, including carbohydrates, proteins, fats, vitamins, and minerals. This is facilitated by its large surface area due to villi and microvilli.
• Statement II: The large intestine primarily absorbs water and electrolytes (like sodium and potassium) from the remaining indigestible food matter and forms stool.
• Statement III: is incorrect as the stomach primarily functions to break down food into a semi-liquid form (chyme) through mechanical and chemical digestion, but it is not the main site of nutrient absorption.
• Absorption of specific nutrients, such as alcohol and certain drugs, occurs in the stomach, but this is minimal compared to the small intestine.

Additional Information

• Small Intestine:
  • Composed of three sections: the duodenum, jejunum, and ileum, each playing a specific role in digestion and absorption.
  • Villi and microvilli increase the surface area for maximum nutrient absorption.
  • Enzymes from the pancreas and bile from the liver aid in breaking down food particles for absorption.
• Large Intestine:
  • Also called the colon, it is responsible for water absorption, electrolyte balance, and stool formation.
  • Houses gut microbiota, which plays a crucial role in fermenting undigested carbohydrates and producing certain vitamins (like vitamin K).
• Stomach:
  • Secretes gastric juices (hydrochloric acid and enzymes like pepsin) to break down proteins.
  • Its acidic environment helps kill pathogens and activate digestive enzymes.
  • Although limited, the stomach absorbs small amounts of water, alcohol, and certain medications.
• Digestive Process Overview:
  • Digestion begins in the mouth (mechanical and enzymatic), continues in the stomach (chemical breakdown), and is completed in the small intestine (nutrient absorption).
  • The large intestine finalizes the process by absorbing water and forming waste for excretion.

The correct answer is Bile juice, Pancreatic juice.

Key Points

• Bile juice, Pancreatic juice secreted by the organs plays an important role in the digestion of fats.
• Bile juice is secreted by the liver.
  • It does not contain any types of enzymes.
  • The bile juice helps to make the food alkaline and break down the fat molecules.
• Pancreatic juice is secreted by the pancreas.
  • It contains enzymes like amylase, trypsin, pancreatic lipase, nucleases and lipase.
  • Secretion of the Pancreatic juice is regulated by the hormones secretin and cholecystokinin.
• Lipase is the digestive enzyme of fat.
• Ptyalin is the digestive enzyme of the Saliva.
• Hydrochloric acid is produced naturally in the human stomach to help the digestion of food.

The correct answer is Starch.

Key Points

• Saliva is a watery and usually somewhat frothy substance produced in the mouths of some animals, including humans.
• Produced in salivary glands, saliva is 98% water, but it contains many important substances, including electrolytes, mucus, antibacterial compounds, and various enzymes.
• The digestive functions of saliva include moistening food and helping to create a food bolus, so it can be swallowed easily.
• Saliva contains the enzyme amylase that breaks some starches down into maltose and dextrin.
• Thus, digestion of food occurs within the mouth, even before the food reaches the stomach.
• Saliva does not digest the proteins. fats and fibres.

Hint

The correct answer is Small intestine.

Key Points

• The small intestine is the longest part of the digestive system.
• The length of the small intestine is 7 meters (22 feet).
• The main functions of the small intestine are to complete the digestion of food and to absorb nutrients. 
• Passage of food through the small intestine normally takes three to six hours.
• Bile, pancreatic enzymes, and alkaline juice (HCO3^–) are the three main substances that are received by the small intestine.
• The small intestine is divided into the duodenum, jejunum, and ileum.
• Iron is absorbed in the duodenum, most are absorbed in the jejunum and Vitamin B12 and bile salts are absorbed in the latter part of the ileum.

The correct answer is carbohydrates.

Key Points

• The human digestive system consists of two parts, the alimentary canal, and the associated glands.
  • The mouth leads the food to be digested to the buccal cavity.
    • The buccal cavity has a number of teeth and a muscular tongue.
    • The uppermost part of the buccal cavity is called the palate.
    • The digestion of carbohydrates begins in the buccal cavity.
  • From the mouth, food reaches into the stomach through a food pipe called the esophagus.
  • There is no digestion inside the food pipe.
  • The digestion of fat begins in the small intestine.
    • Lipase is the digestive enzyme of fat.
  • The digestion of protein occurs in the stomach and duodenum.
    • Pepsin is the digestive enzyme of protein.

The correct answer is To protect the lining of the stomach.

Key Points

• Mucus or Gastric mucus is a gel barrier secreted by epithelial cells & glandular cells in the stomach wall.
• Important Points

• HCL: converts the medium of food from alkali to acidic that also enables pepsin to do its work.
• Mucus: protects the inner lining of the stomach from HCL.
• Pepsin: helps in breaking down or digestion of protein in the stomach.
• Hydrochloric acid helps in the functionality of pepsin at the same time kills bacteria and mucus.

The correct answer is Buccal cavity

Key Points:The human digestive system consists of two parts, the alimentary canal, and the associated glands.

• The mouth leads the food to be digested to the buccal cavity.
  • The buccal cavity has a number of teeth and a muscular tongue.
  • The uppermost part of the buccal cavity is called the palate.
  • The digestion of carbohydrates begins in the buccal cavity.
• From the mouth, food reaches into the stomach through a food pipe called the esophagus.
• There is no digestion inside the food pipe.
• The digestion of fat begins in the stomach.
  • Lipase is the digestive enzyme of fat.
• The digestion of protein occurs in the stomach and duodenum.
  • Pepsin is the digestive enzyme of protein.

Additional Information Digestive system:

• It consists of the long alimentary canal and associated glands.
• The alimentary canal includes
  • Mouth (buccal cavity)
  • Oesophagus (food pipe)
  • Stomach
  • Small intestine
  • Large intestine

The glands associated with the digestive system are as follows: 

• Liver 
• Pancreas 
• Intestinal glands

Explanation:

• The correct option is 4 Sub-mucosa, It contains nerves and blood vessels. 
• The wall of the alimentary canal from oesophagus to rectum possesses four layers namely serosa, muscularis, sub-mucosa, and mucosa.
• Serosa: The serosa is the outermost layer and is made up of a thin mesothelium (epithelium of visceral organs) with some connective tissues. It is also called tunica adventitia in the oesophagus.
• Muscularis: Muscularis is formed by smooth muscles usually arranged into an inner circular and an outer longitudinal layer. An oblique muscle layer may be present in some regions.
• Sub-mucosa: The submucosal layer is formed of loose connective tissues containing nerves, blood, and lymph vessels. In the duodenum, glands are also present in the sub-mucosa.
• Mucosa: It is the innermost layer of the gut that contains the secretory and absorptive cells. This layer forms irregular folds (rugae) in the stomach and small finger-like foldings called villi in the small intestine. It is differentiated into 3 parts:

1. The outer part called mucosa muscularis: It is made up of longitudinal and circular muscles. It has an important role in exposing surface area for the absorption
2. The middle part called lamina propria. It contains few modified lymphatic tissues which provide immunity. Eg. peyer's patches.
3. The innermost part called the mucosal layer.

The correct answer is Large Intestine.

Important Points

• The digestive system of humans consists of the mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine, large intestine, rectum, anus, and associated digestive glands.
• Digestion begins in the mouth.
• The oesophagus is the part that connects the mouth to the stomach.
  • Protein digestion takes place in the Stomach.
  • Simple sugars, alcohol, and medicines are absorbed in the stomach.
• The nutrients in digested food are absorbed from the small intestine.
• Maximum absorption occurs in the small intestine.

Key Points

• The large intestine helps in the absorption of water and some salts from the undigested food materials.
• The main functions of the large intestine are:
  • Absorption of some water, minerals, and certain drugs.
  • Secretion of mucus which helps in adhering the waste (undigested),
• ​Salivary glands, liver, gallbladder, and pancreas are associated with the alimentary canal.

The correct answer is Stomach.

Mistake Points

• The enzyme pepsin digests proteins and, the Chief cells of the stomach secrete the enzyme pepsin along with HCL So the digestion of protein begins in the stomach.  

Key Points

• Protein is one of the most important substances in the body.
• The digestion of protein begins in the stomach.
• Chief cells or peptic cells of the stomach secrete proenzyme pepsinogen. The proenzyme pepsinogen on exposure to hydrochloric acid gets converted into the active enzyme pepsin
• The enzyme pepsin is responsible for the digestion of proteins.
• Pepsin converts proteins into proteases and peptones.

Important Points

• Parietal or Oxyntic cells of the stomach secrete HCL ad intrinsic factor 

Additional Information

• The liver produces bile to help break down and absorb fats.
• Waste products and toxins are removed through bile.
• The small intestine is the part of the intestines where 90% of the digestion and absorption of food occurs.
• The body recycles amino acids to make more proteins.