Digestive System MCQ for RRB & SSC and other Competitive exams
21
The finger-like projections in the small intestine that increase surface area for absorption are called?
✓ Answer:
B
Villi
Villi are finger-like projections on the inner wall of the small intestine. Each villus contains a lacteal (lymph capillary for fat absorption) and blood capillaries (for glucose and amino acid absorption). Villi are further covered with Microvilli forming the brush border.
22
Which is the longest part of the alimentary canal?
✓ Answer:
B
Small Intestine
The small intestine is approximately 6-7 metres long, making it the longest part of the alimentary canal. It consists of the Duodenum, Jejunum, and Ileum. The large intestine is wider but only about 1.5 metres long.
23
The liver receives blood from which two sources?
✓ Answer:
B
Hepatic Artery and Hepatic Portal Vein
The liver has a dual blood supply: Hepatic Artery brings oxygenated blood from the heart, and Hepatic Portal Vein brings nutrient-rich blood from the digestive organs. This is why the liver is the first organ to process absorbed nutrients - called the First Pass Effect.
24
Which of the following is the correct order of the human digestive system?
✓ Answer:
C
Mouth > Oesophagus > Stomach > Small Intestine > Large Intestine
The correct order of the alimentary canal is: Mouth > Pharynx > Oesophagus > Stomach > Small Intestine (Duodenum > Jejunum > Ileum) > Large Intestine (Caecum > Colon > Rectum) > Anus.
25
What is the pH of gastric juice?
✓ Answer:
C
1-2
Gastric juice has a highly acidic pH of 1-2 due to the presence of Hydrochloric Acid (HCl). This acidic environment activates pepsinogen into pepsin and kills most ingested bacteria, acting as a defense mechanism.
26
What is the total length of the human alimentary canal approximately?
✓ Answer:
B
9 metres
The human alimentary canal (digestive tract) is approximately 9 metres long from mouth to anus. This includes the oesophagus (~25 cm), stomach, small intestine (~6-7 m), and large intestine (~1.5 m). The small intestine alone makes up the majority of this length.
27
Trypsin is secreted by which organ?
✓ Answer:
C
Pancreas
Trypsin is secreted by the pancreas as inactive Trypsinogen, which is activated by Enterokinase (secreted by the intestinal wall). Trypsin digests proteins into smaller peptides in the small intestine. It works best in an alkaline pH.
28
What is the function of the large intestine?
✓ Answer:
C
Absorption of water and formation of faeces
The large intestine absorbs water and salts from undigested food and forms faeces. Some vitamins like Vitamin K produced by gut bacteria are also absorbed here. Major digestion happens in the small intestine, not here.
29
Which enzyme is responsible for the digestion of proteins in the stomach?
✓ Answer:
C
Pepsin
Pepsin digests proteins into peptides in the stomach. It is secreted as inactive Pepsinogen and activated by HCl. Trypsin also digests proteins but works in the small intestine. Lipase acts on fats, amylase on carbohydrates.
30
Which organ is both an exocrine and endocrine gland?
✓ Answer:
C
Pancreas
The Pancreas is a mixed gland. Exocrine function: secretes pancreatic juice (amylase, lipase, trypsin) into the duodenum. Endocrine function: secretes Insulin and Glucagon directly into the blood from the Islets of Langerhans.