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

Ptylin enzyme is present in the

  1. stomach

  2. pancreas

  3. liver

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

Ptyalin (also known as salivary amylase) is an enzyme present in saliva, which is produced in the mouth by salivary glands. It begins the digestion of starch into simpler sugars like maltose. The enzyme works optimally in the slightly acidic to neutral pH of the mouth (pH 6.7-7.0). No ptyalin is present in the stomach, pancreas, or liver.

Multiple choice

When the guard cells are turgid

  1. the stoma is open

  2. the stoma is closed

  3. the stoma becomes flat

  4. it becomes a globe like structure
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When guard cells become turgid due to water uptake, their uneven thickening causes them to bend outward, creating an opening between them. This is the open stomatal pore that allows gas exchange. When flaccid, the stomatal pore closes.

Multiple choice

Which of the following does not secrete any digestive enzyme?

  1. Liver

  2. Salivery gland

  3. Glands of small intestine

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

The liver produces bile but doesn't secrete any digestive enzymes. Bile emulsifies fats (breaks them into smaller droplets) but doesn't chemically digest them. Salivary glands secrete amylase, small intestine glands secrete various enzymes, and the pancreas secretes multiple enzymes like amylase, lipase, and proteases.

Multiple choice

The contractive movement of the indestine which helps in the digestion is known as ________.

  1. metabolism

  2. osmosis

  3. catabolism

  4. peristalsis

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Peristalsis is the wave-like muscular contractions of the digestive tract (especially intestines) that propel food contents forward. This rhythmic contraction and relaxation of smooth muscle is essential for digestion and absorption. Metabolism is all chemical reactions, osmosis is water movement, and catabolism is breakdown of complex molecules.

Multiple choice

Which of the following statements is/are incorrect?

a. Peristaltic movement moves food in all the digestive organs throughout the alimentary canal. b. Food is churned in stomach for three hours and is partially digested. c. Sphincter muscle moves food in small amounts into the stomach from the food pipe.

  1. a only

  2. b only

  3. c only

  4. a and c

  5. b and c
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is the correct answer as this statement is incorrect. The exit of food from stomach is regulated by a sphincter muscle, which releases it in small amounts into the small intestine.

Multiple choice

Which of the following is correct about mucus?

  1. It is alkaline and contains salts which help to emulsify lipids.

  2. It makes the medium of gastric juice acidic so that enzyme pepsin can digest proteins.

  3. It breaks the fats present in food.

  4. It digests starch present in food to form sugar.

  5. It protects stomach wall from its own secretions of hydrochloric acid.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct answer. Mucus protects stomach wall from its own secretions of hydrochloric acid.

Multiple choice

Which of the following is the correct statement about the large intestine of the human body?

  1. The absorption of food occurs here.

  2. The assimilated food is stored here.

  3. It absorbs water from undigested food.

  4. It stores digested food that is not used immediately by the body.

  5. It stores faeces.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is the correct answer as the villi present in the inner surface of the large intestine absorbs most of the water from the undigested food.