Biology ยท Science General

Human Digestive System

2,002 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

Digestion of food starts in the

  1. mouth

  2. liver

  3. stomach

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

Digestion begins in the mouth, where mechanical breakdown by teeth and chemical breakdown by saliva (amylase) start the process.

Multiple choice

Which of the following statements regarding the digestion of proteins in allimentary canal is INCORRECT?

  1. Rennin is normally only produced by infant mammals.

  2. Pepsin is an exopeptidase.

  3. Protease enzymes are potentially dangerous.

  4. Exopeptidases remove amino acids one by one from the ends of peptide chains.

  5. Pancreatic endopeptidases continue to digest proteins in the duodenum.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Pepsin (in gastric juice) digests proteins to peptides, 6-12 amino acids long. Pepsin is an endopeptidase, which means it hydrolyses peptide bonds in the middle of a polypeptide chain. It is unusual in that it has an optimum pH of about 2 and stops working at neutral pH.

Multiple choice

The lining wall of the alimentary canal appears different in different parts of the gut, reflecting their different roles, but always has the same basic layers. Which of the following layers prevents food from traveling backward?

  1. The muscularis externa

  2. The gastric mucosa

  3. The submucosa

  4. The serosa

  5. The oral mucosa
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The muscularis externa consists of an inner circular layer and a longitudinal outer muscular layer. The circular muscle layer prevents food from traveling backward and the longitudinal layer shortens the tract.

Multiple choice

Which of the following statements regarding the digestion of carbohydrates in human gut is FALSE?

  1. The ileum enzymes attached to the epithelial cells complete the digestion of disaccharides to monosaccharides.

  2. Salivary amylase starts the digestion of starch.

  3. Pancreatic amylase digests all the remaining starch in the oesophagus.

  4. The plant fibres are pass through the digestive system as fibre.

  5. The monsaccharides are absorbed by active transport.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pancreatic amylase digests all the remaining starch in the duodenum. Amylase digests starch molecules from the ends of the chains in two-glucose units, forming the disaccharide maltose. Glycogen is also digested here.

Multiple choice

Which of the following statements regarding the functions of pancreas is INCORRECT?

  1. Pancreatic secretions from ductal cells contain bicarbonate ions.

  2. The pancreas secretes lysophospholipase and cholesterol esterase.

  3. The pancreas is also the main source of enzymes for polysaccharides.

  4. The control of the exocrine function of the pancreas is done through the hormones.

  5. Progenitor cells of the pancreas differentiate to form two lines of committed endocrine precursor cells.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pancreas is also the main source of enzymes for digesting fats (lipids) and proteins. The enzymes that digest polysaccharides, by contrast, are primarily produced by the walls of the intestines.

Multiple choice

Which of the following digestive ducts participates in ion and water transport and secretes kallikrein?

  1. An intercalated duct

  2. A striated duct

  3. An excretory intralobular duct

  4. Intralobular ducts

  5. Interlobular ducts
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The striated duct is well developed in the submandibular gland. The epithelium of the striated duct participates in ion and water transport and secretes kallikrein. A segment of this duct is lined by cuboidal-to-columnar epithelial cells with basal infoldings containing numerous mitochondria.

Multiple choice

The digestive system is responsible for taking in whole food and turning them into energy and nutrients to allow the body to function, grow, and repair itself. Which of the following processes occurs only in the small intestine?

  1. Secretion

  2. Peristalsis

  3. Swallowing

  4. Absorption

  5. Segmentation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Segmentation occurs only in the small intestine as short segments of intestine contract. Segmentation helps to increase the absorption of nutrients by mixing food and increasing its contact with the walls of the intestine.

Multiple choice

In which part of the allimentary canal some of the water and electrolytes are removed from the food?

  1. In the mouth

  2. In the esophagus

  3. In the stomach

  4. In the large intestine

  5. In the small intestine
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

After passing through the small intestine, food passes into the large intestine. In the large intestine, some of the water and electrolytes (chemicals like sodium) are removed from the food. Many microbes (bacteria like Bacteroides, Lactobacillus acidophilus, Escherichia coli, and Klebsiella) in the large intestine help in the digestion process.
After being in the stomach, food enters the duodenum. In the small intestine, bile (produced in the liver and stored in the gall bladder), pancreatic enzymes, and other digestive enzymes produced by the inner wall of the small intestine help in the breakdown of food.