Biology · 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

Which of the following statements is incorrect?

  1. Serosa is the outermost layer of the alimentary canal and is made up of squamous epithelium.

  2. Submucosal layer is made up of loose connective tissues.

  3. Mucosa is made up of an outer circular muscle layer and an inner longitudinal muscle layer.

  4. Submucosa contains nerve cells called submucous plexus.

  5. The lamina propria is the middle layer of mucosa.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Mucosa is the innermost layer of the wall of the alimentary canal which is devoid of circular and longitudinal muscles. Instead, it consists of glands responsible for the secretion of mucus and other enzymes.

Multiple choice

The principal action of the enterokinase present in the human intestinal juice is to-

  1. Hydrolyse casein into paracasein

  2. Act of the terminal peptide bond of peptide chain to release the last amino acid.

  3. Convert pro-carboxypeptidase to carboxypeptidase

  4. Activate the trypsinogen of the pancreatic juice.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enterokinase (also called enteropeptidase) is a protease enzyme produced in the duodenum. Its primary and most important function is to activate trypsinogen (the inactive precursor) into trypsin by cleaving off an activation peptide. Trypsin then activates other pancreatic zymogens (procarboxypeptidase, chymotrypsinogen, etc.) creating a digestive enzyme cascade. Options A, B, and C describe functions of other enzymes.

Multiple choice

With reference to the human body, which one of the following statement is correct?

  1. Lipases are insoluble in water.

  2. Trypsin acts best in an acidic PH.

  3. Pepsin actions is enhanced in the duodenum by the alkalinity.

  4. Bile salts are steroids.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Bile salts are derived from cholesterol and have a steroid nucleus structure (cyclopentanoperhydrophenanthrene ring system). Lipases are water-soluble enzymes. Trypsin is a pancreatic enzyme that works best in alkaline pH of small intestine. Pepsin is denatured by the alkaline environment of duodenum.

Multiple choice

Directions: This question presents a sentence, all or part of which is underlined. Beneath the sentence you will find five ways of phrasing the underlined part. The first of these repeats the original; the other four are different. If you think the original is best, choose the first answer; otherwise choose one of the others.

Because cows often need to survive on low quality food, they need a way to extract maximum nutrition from the food they eat before being excreted, and therefore, cows have a special stomach called rumen in which food is repeatedly masticated and chewed

  1. they need a way to extract maximum nutrition from the food they eat before being excreted, and therefore, cows have a special stomach called rumen in which food is repeatedly masticated and chewed

  2. they need a way to extract maximum nutrition from the food they eat before it being excreted, and therefore, cows have a special stomach called rumen in which food is repeatedly masticated and chewed

  3. they need a way to extract maximum nutrition from the food they eat before being excreted, and therefore, cows have a special stomach called rumen by which food is repeatedly masticated after being chewed

  4. they need a way to extract maximum nutrition from the food they have eaten before it is excreted, and therefore, cows have a special stomach called rumen in which food is repeatedly masticated after being chewed

  5. they need a way to extract maximum nutrition from the food they eat before it is excreted, and therefore, cows have a special stomach called rumen in which food is repeatedly masticated after being chewed
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Correct; corrects the antecedent error by adding 'it' before excreted to denote food; clarifies that food is repeatedly masticated AFTER being chewed

Multiple choice

Pepsin is an enzyme found in humans. It was first crystallized by

  1. Theodor Schwann

  2. Louis Pasteur

  3. Robert Koch

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

He was a German physiologist. He is famed for the development of cell theory, the discovery of Schwann cells in the peripheral nervous system, and the discovery and study of pepsin.

Multiple choice

The cells of pancreas are not autodigested by their enzymes as ___________.

  1. its cells are covered by mucus

  2. enzymes are secreted in their inactive forms

  3. enzymes are secreted in active form

  4. these enzymes do not have coenzymes

  5. autodigestion occurs but the cells are renewed many times in the pancreas
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is true that enzymes secreted in the inactive form such as their pro form stops the autodigestion of pancreas from the active forms of the same enzymes.

Multiple choice

When a dilute solution of glucose reaches the small intestine it is _______.

  1. absorbed rapidly by active transport with sodium ions

  2. absorbed by facilitated diffusion like fructose

  3. lost with undigested food as its concentration is very low

  4. absorbed rapidly by passive transport

  5. absorbed slowly
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glucose is rapidly absorbed in the small intestine along with sodium ions by the process called as active transport by co transport.