Part 4: Absorption of Nutrients (25 MCQs)

Q1. The primary site of nutrient absorption in humans is:

A. Stomach
B. Small intestine
C. Large intestine
D. Esophagus

Answer: B

Explanation:

A. Incorrect: Stomach mainly digests proteins, not absorb nutrients.
B. Correct: Small intestine, especially jejunum, is the chief site of absorption.
C. Incorrect: Large intestine mainly absorbs water and salts.
D. Incorrect: Esophagus only transports food.

Q2. Which structure increases the surface area for absorption in the small intestine?

A. Rugae
B. Villi and microvilli
C. Haustra
D. Taeniae coli

Answer: B

Explanation:

A. Incorrect: Rugae are folds in stomach.
B. Correct: Villi and microvilli greatly increase surface area.
C. Incorrect: Haustra are in large intestine.
D. Incorrect: Taeniae coli are muscular bands in large intestine.

Q3. Glucose and amino acids are absorbed into the blood through:

A. Simple diffusion
B. Facilitated diffusion and active transport
C. Pinocytosis
D. Endocytosis only

Answer: B

Explanation:

A. Incorrect: Simple diffusion is insufficient for most.
B. Correct: Both facilitated diffusion and active transport help absorb glucose and amino acids.
C. Incorrect: Pinocytosis occurs for fats in infants, not main for glucose/amino acids.
D. Incorrect: Endocytosis is not the major process.

Q4. Which vitamin is absorbed in the ileum with the help of intrinsic factor?

A. Vitamin A
B. Vitamin B12
C. Vitamin C
D. Vitamin K

Answer: B

Explanation:

A. Incorrect: Vitamin A is absorbed in small intestine but does not need intrinsic factor.
B. Correct: Vitamin B12 absorption requires intrinsic factor secreted by gastric parietal cells.
C. Incorrect: Vitamin C is absorbed by diffusion in small intestine.
D. Incorrect: Vitamin K is absorbed with fats.

Q5. Fats are absorbed in the form of:

A. Micelles
B. Peptides
C. Amino acids
D. Disaccharides

Answer: A

Explanation:

A. Correct: Fats are absorbed as micelles containing fatty acids and monoglycerides.
B. Incorrect: Peptides are protein products.
C. Incorrect: Amino acids are protein products.
D. Incorrect: Disaccharides are carbohydrate intermediates.

Q6. Chylomicrons are formed in:

A. Liver
B. Lacteals of villi
C. Intestinal mucosal cells
D. Pancreas

Answer: C

Explanation:

A. Incorrect: Liver processes chylomicrons but does not form them initially.
B. Incorrect: Lacteals absorb chylomicrons but don’t form them.
C. Correct: Intestinal mucosal cells (enterocytes) re-synthesize triglycerides and form chylomicrons.
D. Incorrect: Pancreas secretes digestive enzymes.

Q7. Which pathway is used for absorption of glycerol and fatty acids?

A. Directly into blood capillaries
B. Into lacteals and lymph
C. Into hepatic portal vein
D. Directly into liver

Answer: B

Explanation:

A. Incorrect: Small fats may enter blood but large ones don’t.
B. Correct: Long-chain fatty acids are absorbed as chylomicrons into lacteals (lymph).
C. Incorrect: Hepatic portal vein carries glucose/amino acids, not fats.
D. Incorrect: Fats don’t go directly to liver.

Q8. Which of the following nutrients is absorbed in the large intestine?

A. Proteins
B. Vitamins (K, B-complex from bacteria)
C. Starch
D. Lipids

Answer: B

Explanation:

A. Incorrect: Proteins absorbed in small intestine.
B. Correct: Some vitamins (K, B12, biotin, folic acid) synthesized by gut microbes are absorbed in large intestine.
C. Incorrect: Starch absorbed as glucose in small intestine.
D. Incorrect: Lipids absorbed in small intestine.

Q9. Amino acids after absorption enter the bloodstream via:

A. Lacteals
B. Hepatic portal vein
C. Thoracic duct
D. Lymph nodes

Answer: B

Explanation:

A. Incorrect: Lacteals absorb fats, not amino acids.
B. Correct: Amino acids enter blood and are carried to liver via hepatic portal vein.
C. Incorrect: Thoracic duct carries lymph (fats).
D. Incorrect: Lymph nodes filter lymph, not main absorption site.

Q10. Sodium-glucose transport is an example of:

A. Active transport (co-transport)
B. Passive diffusion
C. Osmosis
D. Facilitated diffusion

Answer: A

Explanation:

A. Correct: Glucose uptake is coupled with sodium transport using ATP energy.
B. Incorrect: Passive diffusion doesn’t need energy.
C. Incorrect: Osmosis is water movement.
D. Incorrect: Facilitated diffusion does not use sodium gradient.

Q11. Iron is absorbed mainly in:

A. Stomach
B. Duodenum
C. Jejunum
D. Large intestine

Answer: B

Explanation:

A. Incorrect: Stomach only solubilizes iron (Fe³⁺ → Fe²⁺).
B. Correct: Duodenum is primary site of iron absorption.
C. Incorrect: Jejunum is for amino acids, glucose absorption.
D. Incorrect: Large intestine absorbs water, not iron.

Q12. Calcium absorption from intestine is promoted by:

A. Vitamin A
B. Vitamin B12
C. Vitamin C
D. Vitamin D

Answer: D

Explanation:

A. Incorrect: Vitamin A helps vision and epithelial health.
B. Incorrect: Vitamin B12 helps RBC synthesis.
C. Incorrect: Vitamin C aids iron absorption, not calcium.
D. Correct: Vitamin D increases calcium absorption in intestine.

Q13. Which nutrient is absorbed without digestion?

A. Amino acids
B. Monosaccharides
C. Vitamins
D. Fatty acids

Answer: C

Explanation:

A. Incorrect: Proteins must be digested to amino acids.
B. Incorrect: Polysaccharides must be digested before monosaccharide absorption.
C. Correct: Vitamins are absorbed directly without digestion.
D. Incorrect: Fats require digestion before absorption.

Q14. Which mechanism absorbs water in the intestine?

A. Osmosis
B. Active transport
C. Facilitated diffusion
D. Endocytosis

Answer: A

Explanation:

A. Correct: Water absorption occurs via osmosis.
B. Incorrect: Active transport is for ions/glucose.
C. Incorrect: Facilitated diffusion is for certain solutes.
D. Incorrect: Endocytosis is not used for water.

Q15. End-products of fat digestion are absorbed into:

A. Capillaries
B. Lacteals
C. Hepatic portal vein
D. Stomach

Answer: B

Explanation:

A. Incorrect: Capillaries absorb amino acids/glucose.
B. Correct: Lacteals (lymph capillaries) absorb chylomicrons.
C. Incorrect: Hepatic portal vein carries sugars and amino acids.
D. Incorrect: Stomach is not for absorption.

Q16. Which vitamin enhances iron absorption in the gut?

A. Vitamin A
B. Vitamin B1
C. Vitamin C
D. Vitamin D

Answer: C

Explanation:

A. Incorrect: Vitamin A maintains epithelium.
B. Incorrect: Vitamin B1 helps in carbohydrate metabolism.
C. Correct: Vitamin C reduces ferric iron to ferrous for better absorption.
D. Incorrect: Vitamin D enhances calcium absorption.

Q17. Monosaccharides are absorbed mainly by:

A. Endocytosis
B. Facilitated diffusion and active transport
C. Pinocytosis
D. Simple diffusion only

Answer: B

Explanation:

A. Incorrect: Endocytosis is not the main pathway.
B. Correct: Glucose and galactose use sodium-dependent active transport; fructose uses facilitated diffusion.
C. Incorrect: Pinocytosis is for large molecules in infants.
D. Incorrect: Simple diffusion is very limited.

Q18. Which mineral is absorbed by active transport in intestine?

A. Sodium
B. Chloride
C. Potassium
D. Calcium

Answer: D

Explanation:

A. Incorrect: Sodium mostly absorbed by diffusion.
B. Incorrect: Chloride follows sodium passively.
C. Incorrect: Potassium is absorbed passively.
D. Correct: Calcium is absorbed by active transport under Vitamin D influence.

Q19. Short-chain fatty acids are absorbed into:

A. Blood capillaries directly
B. Lymph vessels only
C. Thoracic duct only
D. Stomach

Answer: A

Explanation:

A. Correct: Short-chain fatty acids are water-soluble and enter blood capillaries directly.
B. Incorrect: Long-chain fatty acids go via lymph.
C. Incorrect: Thoracic duct is final pathway for lymph, not direct absorption.
D. Incorrect: Stomach does not absorb fatty acids.

Q20. In which part of the alimentary canal are bile salts reabsorbed?

A. Stomach
B. Jejunum
C. Ileum
D. Colon

Answer: C

Explanation:

A. Incorrect: Stomach does not absorb bile salts.
B. Incorrect: Jejunum absorbs sugars/amino acids.
C. Correct: Ileum reabsorbs bile salts for enterohepatic circulation.
D. Incorrect: Colon absorbs water and electrolytes.

Q21. Vitamin K is absorbed in the intestine with:

A. Carbohydrates
B. Proteins
C. Fats
D. Water

Answer: C

Explanation:

A. Incorrect: Carbohydrates do not aid in vitamin K absorption.
B. Incorrect: Proteins do not help.
C. Correct: Vitamin K is fat-soluble, absorbed with fats.
D. Incorrect: It is not water-soluble.

Q22. Which part of the alimentary canal absorbs the maximum water?

A. Stomach
B. Small intestine
C. Large intestine
D. Rectum

Answer: B

Explanation:

A. Incorrect: Stomach absorbs little water (alcohol/aspirin).
B. Correct: Small intestine absorbs ~90% of water.
C. Incorrect: Large intestine absorbs remaining water.
D. Incorrect: Rectum stores feces.

Q23. The absorbed glucose and amino acids are first transported to:

A. Heart
B. Liver
C. Pancreas
D. Kidneys

Answer: B

Explanation:

A. Incorrect: Heart receives blood after liver processing.
B. Correct: Hepatic portal vein carries them to liver for metabolism.
C. Incorrect: Pancreas secretes hormones, not first site.
D. Incorrect: Kidneys filter after liver processing.

Q24. The lymph vessel of a villus is called:

A. Ductule
B. Lacteal
C. Thoracic duct
D. Venule

Answer: B

Explanation:

A. Incorrect: Ductule is a general small duct.
B. Correct: Lacteal is a lymph capillary in villi for fat absorption.
C. Incorrect: Thoracic duct drains lymph into blood.
D. Incorrect: Venule carries blood, not lymph.

Q25. Micelles help in absorption of:

A. Amino acids
B. Monosaccharides
C. Fatty acids and monoglycerides
D. Vitamins B and C

Answer: C

Explanation:

A. Incorrect: Amino acids absorbed by active transport.
B. Incorrect: Monosaccharides absorbed by diffusion/transport.
C. Correct: Micelles transport fatty acids, monoglycerides, fat-soluble vitamins to mucosa.
D. Incorrect: Vitamins B and C are water-soluble, absorbed directly.

Digestion and Absorption MCQs, CBSE Class 11 Biology, NEET UG Biology Preparation, Human Digestive System Notes, Class 11 Biology Questions, NCERT Biology MCQs PDF, Digestion and Absorption Quiz, NEET UG Biology MCQs, digestion and absorption mcqs for neet, class 11 biology chapter 16 questions, cbse class 11 biology mcqs with answers, human digestive system mcqs ncert, digestion and absorption quiz for neet ug, class 11 biology mcqs for cbse board, ncert biology chapter 16 notes, important mcqs on digestion class 11

Part 4: Absorption of Nutrients (25 MCQs)