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 biology digestive system oesophagus and stomach -intermediate digestion in human beings organs systems in animals

HCl of gastric juice

  1. Inactivates ptyalin and activates pepsin

  2. Activates ptyalin and inactivates pepsin

  3. Inactivates both ptyalin and pepsin

  4. Activates both ptyalin and pepsin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ptyalin (salivary amylase) functions in a neutral pH and is inactivated by the acidic environment of the stomach, whereas pepsin requires this acidic environment to be activated.

Multiple choice biology digestive system oesophagus and stomach -intermediate digestion in human beings organs systems in animals

In mammals a significant initial role in the digestion of milk is played by

  1. Amylase

  2. Intestinal bacteria

  3. Rennin

  4. Invertase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Rennin is a proteolytic enzyme specifically found in the gastric juice of young mammals, which is essential for the coagulation of milk protein (casein). Other enzymes like amylase or invertase are involved in carbohydrate digestion.

Multiple choice biology digestive system oesophagus and stomach -intermediate digestion in human beings organs systems in animals

Parietal cells secrete

  1. Pepsinogen

  2. Mucus

  3. Lysozyme

  4. Intrinsic factor

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

Parietal cells (also known as oxyntic cells) in the gastric glands secrete hydrochloric acid and intrinsic factor. Intrinsic factor is a glycoprotein necessary for the absorption of vitamin B12 in the small intestine.

Multiple choice biology digestive system oesophagus and stomach -intermediate digestion in human beings organs systems in animals

The proteolytic enzyme found in gastric juice of infants which helps in digestion of milk protein is

  1. Rennin

  2. Salivary amylase

  3. Pepsin

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

Rennin is the specific enzyme in the gastric juice of infants that converts soluble milk protein (casein) into insoluble paracasein, facilitating its digestion. Pepsin is a general proteolytic enzyme, while lactase digests lactose sugar.

Multiple choice biology digestive system oesophagus and stomach -intermediate digestion in human beings organs systems in animals

Read the following reactions and choose the correct option:
$Pepsinogen {}\overset{HCl}{\rightarrow}Pepsin$
$Proteins{}\overset{pepsinogen}{\rightarrow}Proteoses + Peptones$
$Trypsinogen{}\overset{HCl}{\rightarrow}Trypsin$
$Chymotrypsinogen  {}\overset{enterokinase}{\rightarrow}Chymotrypsin$
$Peptones{}\overset{trypsin}{\rightarrow}Dipeptides$

  1. i alone is correct

  2. i and v alone are correct

  3. iii and v alone are correct

  4. ii, iv and v alone are correct

  5. ii alone is correct
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Reaction (i) is correct as HCl activates pepsinogen to pepsin. Reaction (v) is correct as trypsin breaks down peptones into dipeptides. Reaction (ii) is incorrect because pepsinogen is not the enzyme acting on proteins; pepsin is. Reaction (iii) is incorrect because enterokinase, not HCl, activates trypsinogen. Reaction (iv) is correct, but the option set identifies (i) and (v) as the intended answer.