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 zoology control and co-ordination in plants and animals the reflex action reflex action and reflex arc basic reflex action and reflex arc

Movement of food in the alimentary canal involves ................... movement.

  1. Voluntary

  2. Regulatory

  3. Involuntary

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

  • Digestion of food, contraction, and relaxation of blood vessels and many other movements are involuntary as we cannot really start or stop them simply by our will. 

Therefore, the correct answer is option C.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

The enzyme ptyalin used for digestion of food is present in:

  1. saliva

  2. blood

  3. intestine

  4. adrenal gland
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Enzymes are macromolecular biological catalysts. These are highly selective catalysts greatly accelerating both the rate and specificity of metabolic reactions. All enzymes are insoluble since they exist in the colloidal state. Urease is an enzyme that catalyzes the hydrolysis of urea, forming ammonia and carbon dioxide.
They decrease the activation energy by providing alternate pathway (enzyme reacts with the substrate to form an intermediate ES complex, which would be impossible in the absence of the enzyme) for the process.
Enzyme + Substrate → Complex → Product + Enzyme
Saliva is a watery substance located in the mouths of animals, secreted by the salivary glands. Human saliva is $99.5\%$ water, while the other $0.5\%$ consists of electrolytes, mucus, glycoproteins, enzymes and antibacterial compounds.
Digestive functions of saliva include moistening food and helping to create a food bolus. This lubricative function of saliva allows the food bolus to be passed easily from the mouth into the esophagus. Saliva contains the enzyme amylase, also called ptyalin, which is capable of breaking down starch into simpler sugars such as maltose and dextrin that can be further broken down in the small intestine. Only about $30\%$ starch digestion takes place in the mouth cavity.
Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

During the process of digestion, the protein present in food materials are hydrolysed to amino acids. The two enzymes involved in the process are:

Proteins $\xrightarrow [ ]{ Enzyme\quad (A) } $ Polypeptides


$\xrightarrow [ ]{ Enzyme\quad (B) } $ Amino acids

  1. Invertase and zymase

  2. Amylase and maltase

  3. Diastase and lipase

  4. Pepsin and trypsin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Pepsin is an enzyme whose zymogen (pepsinogen) is released by the chief cells in the stomach and that degrades food proteins into peptides. 

Trypsin cleaves peptide chains mainly at the carboxyl side of the amino acids lysine or arginine. In the Duodenum, trypsin catalyzes the hydrolysis 
of peptide bonds, breaking down proteins into smaller peptides. The peptide products are then further hydrolyzed into amino acids via other proteases, rendering them available for absorption into the blood stream. Tryptic digestion is a necessary step in protein absorption as proteins are generally too large to be absorbed through the lining of the small intestine.

Hence, option D is correct.
Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

An enzyme present in the saliva of human beings is :

  1. thiamine

  2. riboflavin

  3. amylases

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ptyalin is the starch hydrolyzing enzyme secreted by salivary glands in human beings. It is also called as salivary amylase. Ptyalin secreted in the mouth brings about digestion of starch in the mouth itself.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

$Cl^-$ ions act as activators for:

  1. amylases

  2. peptidases

  3. glycosidases

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

$Cl^{-}$ ions act as activators for amylase enzyme.

Enzyme activators:-Enzyme activators are molecules that bind to enzymes and increase their activity. They are the opposite of enzyme inhibitors. These molecules are often involved in the allosteric regulation of enzymes in the control of metabolism.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

The enzyme ptyalin used for digestion of food is present in: 

  1. saliva

  2. blood

  3. intestine

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

The enzyme ptyalin, also known as amylase is present in saliva and is responsible for breaking down starch into simple sugars such as dextrin and maltose which are further broken down in the intestine

Multiple choice biology life processes: control and coordination nervous system in animals structure of neuron structure and function of neuron

Sight of delicious food usually makes mouth watery, it is a 

  1. Hormonal response

  2. Neural response

  3. Optic response

  4. Olfactory response
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The response to food begins even before food enters the mouth. The first phase of ingestion, called as the cephalic phase, is controlled by the neural response to the stimulus provided by food. All aspects, such as sight, sense, and smell, trigger the neural responses resulting in salivation and secretion of gastric juices. The gastric and salivary secretion in the cephalic phase can also take place at the thought of food. The central nervous system prepares the stomach to receive food. 

Multiple choice zoology control and coordination in living organisms gastrointestinal tract and liver hormones of heart, kidney, liver and gastrointestinal tract coordination in human beings- chemical control

Name the hormone that stimulates the secretion of gastric juice.

  1. Renin

  2. Enterokinase

  3. Enterogastrone

  4. Gastrin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Gastrin is a peptide hormone that stimulates secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the pyloric antrum of the stomach, duodenum and pancreas.

Multiple choice zoology control and coordination in living organisms gastrointestinal tract and liver hormones of heart, kidney, liver and gastrointestinal tract coordination in human beings- chemical control

Hormone involved in the discharge of pancreatic juice in mammals is

  1. Secretin

  2. Gastrin

  3. Cholecystokinin

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

Secretin is produced in the S cells of the duodenum, which are located in the crypts of Lieberkuhn. Secretin helps regulate the pH of the duodenum by inhibiting the secretion of gastric acid from the parietal cells of the stomach and stimulating the production of bicarbonate from the pancreas. 

Multiple choice zoology control and coordination in living organisms gastrointestinal tract and liver hormones of heart, kidney, liver and gastrointestinal tract coordination in human beings- chemical control

Secretin stimulates the activity of

  1. Liver

  2. Parietal cells

  3. Pancreas

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Secretin helps in regulating the $pH$ of the duodenum by

(1) Its inhibit the secretion of gastric acid from the parietal cells of the stomach.
(2) Stimulating the production of bicarbonate from ductal cells of the pancreas.
Secretin also stimulates duct cells in the liver for the release of bicarbonate into the bile.

Multiple choice zoology endocrine system and chemical co-ordination gastrointestinal tract and liver hormones of heart, kidney, liver and gastrointestinal tract coordination in human beings- chemical control

Pancreatic secretion is stimulated by

  1. Secretin

  2. Cholecystokin-Pancreozymin

  3. Duocrinin

  4. Enterogastrone
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cholecystokinin-Pancreozymin (CCK-PZ) is the primary hormone responsible for stimulating the secretion of pancreatic enzymes.