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

When we eat food our stomach expands and it contracts when food goes out. Thus the stomach can expand and contract. All this is possible because our stomach is made up of which of the following components?

  1. Blood

  2. Muscles

  3. Bones

  4. Iron

  5. Skin
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Muscles are one of the crucial organs of our body. They are incredibly sophisticated and can expand and contract when they relax. Our stomach is made up of muscles, so it expands when food goes inside and it contracts when the food goes out. They are long-lasting, self-healing and are able to grow stronger with practice. They do everything from allowing us to walk to keeping our blood flowing.

Multiple choice

Which of the following statements is correct about roughage?

  1. It is easily digestible in the intestine.

  2. It is a kind of protein.

  3. After digestion, it releases energy for the body.

  4. It contains all the nutrients needed to keep body healthy.

  5. Its intake is suggested to reduce obesity.

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

Intake of roughage in a diet is suggested to reduce obesity. 

Multiple choice

What happens to the excess carbohydrates in the body?

  1. They break down into urea and excrete out of the body with urine.

  2. They dissolve into water and excrete out of the body with urine.

  3. They get dissolved in the blood of the body.

  4. They get converted into fat and stored in the form of fats and lipids below the skin.

  5. The take the form of vitamin C after digestion in stomach.

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

The excess carbohydrates in the body get converted and stored in the form of fats and lipids below the skin.
 

Multiple choice

What is pH of saliva in human beings?

  1. 8.0 - 10.0

  2. 7.5 - 8.0

  3. 7.5 - 9.0

  4. 6.7 - 6.9
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Saliva of humans is slightly acidic so as to inhibit the action of harmful microbes. Its pH range is 6.7 - 6.9.

Multiple choice

The gall bladder is meant for __________.

  1. storing bile

  2. concentrating bile

  3. storing and concentrating bile

  4. storing bile and producing it when needed
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The gall bladder is attached with liver and it receives bile from the liver when there is no food in the duodenum for emulsification. Thus, gall bladder stores the bile. Since gall bladder is much smaller than liver, the bile has to be concentrated for storage. Hence, (3) is correct. It should be noted that gall bladder can't produce bile.

Multiple choice

______________ are two hormones that stimulate pancreatic juice secretion.

  1. Cholecystokinin and pancreozymin

  2. Pepsin and rennin

  3. Pancreozymin and pepsin

  4. Rennin and cholecystokinin

  5. Pepsin and cholecystokinin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Correct answer. Cholecystokinin and pancreozymin are two hormones that stimulate the secretion of pancreatic juice. Cholecystokinin causes contraction of the gall bladder and discharges the bile into the duodenum. Pancreozymin also stimulates the pancreas to secrete insulin and glucagon.

Multiple choice

The lining wall of the alimentary canal appears different in different parts of the gut, reflecting different roles, but always has the same basic layers. Which among the following layers prevents food from traveling backward?

  1. The muscularis externa

  2. The gastric mucosa

  3. The submucosa

  4. The serosa

  5. The oral mucosa
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The muscularis externa consists of an inner circular layer and a longitudinal outer muscular layer.

Multiple choice

Which of the following is NOT a function of the stomach?

  1. To digest food using acids, enzymes and peristaltic movements

  2. To store food temporarily

  3. To regulate the release of chyme into the small intestine

  4. To churn the food

  5. To secrete intrinsic factor which is essential for the absorption of fat‐soluble vitamins
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Stomach secretes intrinsic factor required for absorption of vitamin B12, which is a water-soluble vitamin.

Multiple choice

Which cells secrete gastric enzymes in the stomach?

  1. Chief cells

  2. Alpha cells

  3. Islets of langerhans

  4. Beta cells

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

Chief cells (also called peptic cells or zymogenic cells) in the gastric glands of the stomach secrete pepsinogen, which converts to active pepsin for protein digestion. Alpha and beta cells are found in pancreatic islets of Langerhans and secrete glucagon and insulin respectively. Option A correctly identifies chief cells. Islets of Langerhans (C) is the pancreatic region containing alpha and beta cells, not a gastric cell type.

Multiple choice

In which of the following mediums is pepsin active?

  1. Acid

  2. Alkaline

  3. Neutral

  4. Isotonic

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

Pepsin is a protease (protein-digesting enzyme) that functions optimally in acidic conditions (pH 1.5-2). The stomach's hydrochloric acid provides this acidic environment and also converts pepsinogen to active pepsin. In alkaline, neutral, or isotonic conditions, pepsin becomes denatured or inactive. Option A correctly states pepsin is active in acid. Pepsin would be inactive in alkaline (B), neutral (C), or isotonic (D) environments.

Multiple choice

Gastric juice contains

  1. pepsin, lipase and rennin

  2. trypsin, lipase and rennin

  3. trypsin, pepsin and lipase

  4. trypsin, pepsin and rennin

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

Gastric juice contains pepsin (protease), gastric lipase (fat-digesting), and rennin/chymosin (milk-clotting, particularly in infants). Trypsin is a pancreatic enzyme, not a gastric enzyme - it's secreted by the pancreas into the small intestine. Option A correctly lists gastric juice components. Options B, C, and D incorrectly include trypsin, which is pancreatic, not gastric.

Multiple choice

Stomach has acidic medium due to

  1. secretion of mucus by gastric epithelium

  2. secretion of bile

  3. secretion of pancreatic juice

  4. secretion of HCl by gastric glands

  5. secretion of digestive enzymes
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The stomach maintains an acidic pH primarily through hydrochloric acid (HCl) secretion from parietal cells in the gastric glands. This acidic environment (pH 1.5-2) is essential for activating digestive enzymes and killing ingested pathogens. Mucus secretion (option A) protects the stomach lining, while bile (B) and pancreatic juice (C) are secreted into the small intestine, not the stomach.