Top 50+ Digestion and Absorption - Biology Questions and Answers For NEET 2024 Exam Preparation

Q1. How many salivary glands are present in the human body?

1. 4
2. 3
3. 5
4. 6

Answer: (d)

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Q2. A young infant may be feeding entirely on mother's milk which is white in colour but the stools which the infant passes out is quite yellowish. What is this yellow colour due to?

1. Pancreatic juice poured into duodenum
2. Undigested milk protein casein
3. Bile pigments passed through bile juice
4. Intestinal juice

Answer: (c)

The yellow colour is due to the presence of bile pigments (bilirubin-yellow). Bile pigments are excretory products. Bile is a bitter-tasting greenish- yellow alkaline fluid produced by the liver, stored in the gall bladder, and secreted into the duodenum of vertebrates.

It assists the digestion and absorption of fats by the action of bile salts, which chemically reduce fatty substances and decrease the surface tension of fat droplets so that they are broken down and emulsified.

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Q3. The centre of hunger or centre which regulates the amount of food we eat or out appetite is located in –

1. Cerebrum
2. Medulla
3. Hypothalamus
4. Alimentary canal

Answer: (c)

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Q4. When a piece of bread is chewed it tastes sweet because

1. Saliva converts starch into maltose
2. The sugar contents are drawn out
3. It does not taste sweet
4. The taste buds are stimulated by chewing

Answer: (a)

Because saliva converts starch into maltose.

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Q5. Which of the following enzyme/digest milk protein in alkaline medium?

1. Trypsin
2. Pepsin
3. Rennin
4. Chymotrypsin

Answer: (d)

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Q6. Jaundice occurs due to the increasing level of

1. $HCO_3$
2. $CaCO_3$
3. Bile pigments
4. $CO_2$

Answer: (c)

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Q7. Which of the following is a highly coiled part of small intestine?

1. Jejunum
2. Duodenum
3. Ileum
4. All of these

Answer: (c)

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Q8. Duodenum has characteristic Brunner's glands which secrete two hormones called

1. prolactin, parathormone
2. secretin, cholecystokinin
3. kinase, estrogen
4. estradiol, progesterone

Answer: (b)

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Q9. The main function of lacteals in the villi of small intestine is the absorption of

1. glucose and vitamins
2. amino acids and glucose
3. water and mineral salts
4. fatty acids and glycerol

Answer: (d)

Lacteals is a lymphatic vessel in a villus of the small intestine which conveys chyle from the intestine through the mesenteric glands to the thoracic duct. The main function of the lacteals in the villi of small intestine is the absorption of fatty acids and glycerol.

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Q10. A polysaccharide which is synthesized and stored in liver cells is

1. lactose
2. glycogen
3. arabinose
4. galactose.

Answer: (b)

The polysaccharide which is synthesized and stored in the liver is glycogen. When there is a need of energy in the body, the glycogen is converted into glucose which is released into the blood to be reached to the target cell.

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Q11. In man the zymogen or chief cells are mainly found in

1. duodenum
2. pyloric part of stomach
3. cardiac part of stomach
4. fundic part of stomach

Answer: (d)

Zymogen or chief cells are present in the fundic part of stomach. Chief cells are usually basal in location and secrete gastric digestive enzymes as proenzymes or zymogens; pepsinogen and prorennin.

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Q12. Each lobule in liver is covered by a thin connective tissue sheath called

1. Glisson's Capsule
2. Hepatic Fascia
3. Falciform ligament
4. Coronary ligament

Answer: (a)

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Q13. How does a gastrovascular cavity differ from an alimentary canal? The gastrovascular cavity

1. has only one opening.
2. is usually much larger.
3. stores food but does not digest it.
4. functions in digestion but not absorption.

Answer: (a)

A gastrovascular cavity has a single opening.

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Q14. Protection of the walls of the stomach against the action of its own digestive juices

1. is controlled by a centre in the medulla of the brain.
2. results from the nervous reactions of the lining of the stomach.
3. results from the presence of an anti-enzyme chemical formed by the gastric glands
4. results from the neutralizing, buffering, and a coating mucus covering its inner surface

Answer: (d)

The stomach is protected from digestive enzymes and low pH by the neutralizing, buffering, and coating mucus secreted over its inner surface.

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Q15. The ______ is primarily a storage chamber within the digestive system, while the ______ reabsorbs water, ions, and generates the faeces.

1. stomach; hindgut
2. crop; midgut
3. buccal cavity; midgut
4. buccal cavity; hindgut

Answer: (a)

the stomach stores food (and performs some digestion too) before passing it on to the intestines. The small intestine (midgut) finishes tint digestion and carries out most of the nutrient absorption, while the large intestine (hindgut) reabsorbs water and ions.

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Q16. Which enzymes are likely to act on the baked potatoes eaten by a man, starting from the mouth and as it moves down the alimentary canal?

1. Salivary amylase → Pancreatic amylase → Disaccharidases
2. Disaccharidase like maltase → Lipases → Nucleases
3. Pancreatic amylase → Salivary amylase → Lipases
4. Salivary maltase → Carboxypeptidase → Trypsinogen

Answer: (a)

Baked potatoes consist of starch which is a polysaccharide. In oral cavity, the food is mixed with saliva. The saliva contains an enzyme called salivary amylase (also called ptyalin) which converts starch into maltose, isomaltose and small dextrins. Salivary amylase is activated in the saliva by the chloride ions.

Starch $→ ↖ {\text"Salivary"} ↙ {\text"amylase"}$ Maltose + Isomaltose + α- Dextrins

The pancreatic juice (present in small intestine) contains starch digesting enzyme, called pancreatic amylase which converts starch into maltose, isomaltose and α-dextrins.

Starch $→ ↖ {\text"Pancreatic"} ↙ {\text"α-amylase"}$ Maltose + Isomaltose + α- Dextrins

Further, disaccharidases such as maltase (present in intestinal juice in small intestine) breakdown disaccharides such as maltose into monosaccharides or simpler sugars.

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Q17. A person suffering from the deficiency of the visual pigment rhodopsin is advised to take more

1. carrot and ripe papaya
2. apple and grapes
3. radish and potato
4. guava and ripe banana

Answer: (a)

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Q18. Pylorus occurs between –

1. Duodenum and ileum
2. Ileum and rectum
3. Stomach and duodenum
4. Oesophagus and stomach

Answer: (c)

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Q19. For its activity, carboxypeptidase requires

1. niacin
2. iron
3. zinc
4. copper

Answer: (c)

Carboxypeptidase is an enzyme synthesized in pancreas and secreted into small intestine. It contains Zn (II) ions as a metal ion cofactor.

This enzyme helps in protein digestion and becomes active in alkaline medium. It is mainly involved in the conversion of large peptides or polypeptides into dipeptides and amino acids.

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Q20. Match the following digestive processes given in column I with their correct description given in column II and then choose the correct option.

Codes:

1. A – IV; B – I; C – II; D – III
2. A – I; B – II; C – III; D – IV
3. A – III; B – IV; C – II; D – I
4. A – I; B – III; C – IV; D – II

Answer: (c)

Ingestion means intake of food. Mechanical digestion comprises of mastication or chewing, liquefaction of food by digestive juices, swallowing and peristalsis.

Chemical digestion includes the enzymatic action on foods. Defecation is the elimination of faecal matter which is formed by undigested food along with water and excess of digestive enzymes.

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Q21. Which of the following is correct pairing of site of action and substrate of rennin?

1. Stomach - Casein
2. Small intestine - Protein
3. Mouth - Starch
4. Stomach - Fat

Answer: (a)

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Q22. Enterokinase is

1. An enzyme that activates the enzymes of pancreatic juice
2. A hormone that prevents the secretion of gastric juice
3. An enzyme that activates the proteolytic enzymes of succus entericus
4. A hormone that prevents the secretion of pancreatic juice

Answer: (a)

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Q23. The contraction of gall bladder is due to

1. cholecystokinin
2. secretin
3. gastrin
4. enterogasterone

Answer: (a)

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Q24. A person who is eating boiled potato, his food contains the component

1. lactose which is not digested
2. starch which is not digested
3. cellulose which is digested by cellulase
4. DNA which can be digested by pancreatic DNase.

Answer: (d)

Boiled potatoes do not contain lactose; and cellulose which is present is not digested in man as he lacks cellulase. Starch is the major food component which is present in boiled potato and is broken down into maltose and isomaltose due to salivary amylase and is hence digested. DNA is broken down into purines, pyrimidines and sugars by pancreatic nuclease (such as DNase).

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Q25. Glucose, some amino acids and sodium are absorbed into blood by

1. Active transport
2. Simple diffusion
3. Facilitated transport
4. The statement is incorrect since they are absorbed in lymph and not in blood

Answer: (a)

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Q26. A healthy person eats the following diet - 5 gm raw sugar, 4 gm albumin, 10 gm pure buffalo ghee adulterated with 2 gm vegetable ghee (hydrogenated vegetable oil) and 5 gm lignin. How many calories he is likely to get?

1. 126
2. 144
3. 164
4. 112

Answer: (b)

Physiological value of carbohydrates is 4.0 kcal/g,

proteins 4.0 kcal/g and of fats is 9.0 kcal/g.

Hence, 5g raw sugar will yield

5 × 4.0 = 20.0 kcal

4 g albumin (protein) will yield

4 × 4.0 = 16.0 kcal

10 + 2 g of fat will yield

12 × 9.0 = 108.0 kcal

Total yield = 144 kcal.

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Q27. Where is protein digestion accomplished?

1. Rectum
2. Ileum
3. Stomach
4. Duodenum

Answer: (b)

Protein digestion starts in the stomach with the action of enzyme pepsin. Then in the duodenum it is carried out by the action of trypsin, chymotrypsin and carboxypeptidases. Then it is done by aminopeptidases and dipeptidases, enterokinases in jejunum and then it ends in the ileum.

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Q28. During prolonged fasting

1. first carbohydrates are used up, followed by fat and proteins towards end.
2. first fats are used up, followed by carbohydrates from liver and muscles and proteins in the end.
3. first lipids, followed by proteins and carbohydrates towards end.
4. none of the above.

Answer: (a)

During prolonged fasting, first carbohydrate are used up, followed by fat and proteins towards the end.

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Q29. Read the following four statements (i) - (iv) with certain mistakes in two of them.

1. Fructose is generally absorbed by simple diffusion.
2. The digestive wastes, solidified into coherent faeces in the rectum initiate an endocrinal action causing an urge or desire for its removal
3. The food mixes thoroughly with the acidic gastric juice of the stomach by the churning movements of its muscular wall and is called the chyme.
4. The secretions of the brush border cells of the mucosa along with the secretions of the goblet cells constitute the succus entericus.

1. iii and iv
2. ii and iii
3. i and ii
4. i and iii

Answer: (c)

Fructose is generally absorbed by facilitated transport. The digestive wastes, solidified into coherent faeces in the rectum initiate a neural reflex causing an urge or desire for its removal.

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Q30. Which one of the following pairs of the kind of cells and their secretion is correctly matched?

1. Kupffer cell - a digestive enzyme that hydrolyses nucleic acids
2. Alpha cells of islets of Langerhans - secretion that decreases blood sugar level
3. Oxyntic cells - a secretion with pH between 2.0 and 3.0
4. Sebaceous glands - a secretion that evaporates for cooling

Answer: (c)

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Q31. A gland not associated with the alimentary canal is

1. adrenal
2. pancreas
3. liver
4. salivary glands

Answer: (a)

Adrenal gland is present at the anterior part of each kidney acting as an endocrine gland, involved in regulating body growth and developmental mechanisms. It is not associated with the alimentary canal.

Pancreas located posterior to the stomach in the abdominal cavity, is associated with the secretion of alkaline pancreatic juices which are essential in the digestion of starch, protein, fats and nucleic acid. Pancreas also produces hormones like glucagon, insulin, and somatostatin are involved in glucose metabolism.

Liver is the largest gland in the body present in the upper right side of the abdominal cavity just below the diaphragm. It is mainly involved in the production of bile which helps in the digestion of fats in small intestine by process of emulsification.

Salivary glands are situated just exterior to the buccal cavity. They discharge their secretions (salivary juices)in the oral cavity, which helps in the mastication of food.

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Q32. The muscular activities of different parts of alimentary canal also be regulated by

1. CNS neural control
2. Local neural control
3. Both (a) and (b)
4. None of these

Answer: (c)

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Q33. Which one of the following statements is true regarding digestion and absorption of food in humans?

1. About 60% of starch is hydrolysed by salivary amylase in our mouth.
2. Chylomicrons are small lipoprotein particles that are transported from intestine into blood capillaries.
3. Fructose and amino acids are absorbed through intestinal mucosa with the help of carrier ions like $Na^{+}$ .
4. Oxyntic cells in our stomach secrete the proenzyme pepsinogen.

Answer: (c)

Glucose and galactose are absorbed by active transport. Sodium pump of the cell membrane helps in it active take up. Fructose is absorbed by facilitated diffusion that involves a specific transmembrane carrier.

Amino acids are absorbed by active transport coupled with active sodium transport. They also enter the blood stream.

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Q34. Caecum is large for digestion of cellulose with the help of symbiotic bacteria in

1. Rabbit
2. Man
3. Cat
4. Frog

Answer: (a)

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Q35. Which one of the following is a fat-soluble vitamin and its related deficiency disease?

1. Calciferol - Pellagra
2. Cobalamine - Beriberi
3. Retinol - Xerophthalmia
4. Ascorbic acid - Scurvy

Answer: (c)

Retinol (vitamin A) and calciferol (vitamin D) are fat soluble vitamins but the pellagra is not the deficient disease of calciferol. Vitamin A cannot be synthesised by mammals and other vertebrates and must be provided in the diet.

Green plants contain precursors of the vitamin, notably carotenes, that are converted to vitamin A in the intestinal wall and liver. The aldehyde derivative of vitamin A, retinal, is a constituent of the visual pigment rhodopsin. Deficiency affects the eyes, causing night blindness, xerophthalmia (dryness and thickening of the cornea), and eventually total blindness. Pellagra is caused by the deficiency of vitamin $B_3$ or nicotinic acid or niacin.

Cobalamine and ascorbic acid (vitamin C) are water soluble vitamins. They are generally found together in the same foods with the exception of $B_{12}$ (cobalamine). The deficient disorders related to cobalamine, vitamin C and calciferol are –

Cobalamine – Pernicious anaemia

Ascorbic acid (vitamin C) – Scurvy

Calciferol (vitamin D) – Rickets (in children) and osteomalacia in adults.

Beri-beri is caused by the deficiency of vitamin $B_1$ (Thiamine).

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Q36. In the stomach, gastric acid is secreted by the:

1. parietal cells
2. gastrin secreting cells
3. peptic cells
4. acidic cells

Answer: (a)

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Q37. Which of the following pair is characterised by swollen lips, thick pigmented skin of hands and legs and irritability?

1. Nicotinamide — Pellagra
2. Protein — Kwashiorkor
3. Thiamine — Beri-beri
4. Iodine — Goitre

Answer: (b)

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Q38. The enzymes that is not present in succus entericus is :

1. nucleases
2. maltase
3. lipase
4. nucleosidase

Answer: (a)

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Q39. The sphincter of Oddi is present between

1. pyloric stomach and duodenum.
2. oesophagus and cardiac stomach.
3. hepatic duct and cystic duct.
4. hepatopancreatic duct and duodenum.

Answer: (d)

The opening of hepato-pancreatic duct in the duodenum is guarded by sphincter of Oddi.

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Q40. Which of the following acts as a common passage for food and air?

1. Pharynx
2. Larynx
3. Oesophagus
4. Glottis

Answer: (a)

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Q41. Jaundice is a disorder of

1. digestive system
2. skin and eyes
3. excretory system
4. circulatory system

Answer: (a)

Jaundice is a disorder in which skin and eyes turn yellow due to the deposition of bile pigment. This happens when bile made in the liver fails to reach the intestine due to obstruction of the bile duct.

As a result, the bile is absorbed into the blood instead of going to the duodenum and cause yellowing of eyes and skin.

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Q42. Which cells of 'Crypts of Lieberkuhn' secrete antibacterial lysozyme?

1. Kupffer cells
2. Zymogen cells
3. Paneth cells
4. Argentaffin cells

Answer: (c)

Paneth cells, present in the bottom of crypts of Lieberkuhn, are rich in zinc and contain acidophilic granules. There is evidence that these cells secrete antibacterial lysozyme.

Zymogen cells or peptic cells are present in stomach and secrete pepsinogen.

Kupffer cells are present in liver. They are phagocytic in nature and engulf disease causing microorganisms, dead cells, etc.

Argentaffin cells, found in crypts of Lieberkuhn, synthesise hormone secretin and 5- hydroxytryptamine.

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Q43. Which one of the following pairs is not correctly matched?

1. Vitamin-C — Scurvy
2. Vitamin-$B_{1}$ — Beri-beri
3. Vitamin-$B_{12}$ — Pernicious anaemia
4. Vitamin-$B_{2}$ — Pellagra

Answer: (d)

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Q44. Epithelial cells of the intestine involved in food absorption have on their surface

1. microvilli
2. pinocytic vesicles
3. zymogen granules
4. phagocytic vesicles

Answer: (a)

Presence of microvilli on the epithelial cells of intestine increases the surface area for absorption of food.

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Q45. Choose the correct matching pair.

1. Trypsin – Starch
2. Renin – Protein
3. Invertase – Sucrose
4. Amylase – Lactose

Answer: (c)

Invertase is the enzyme that catalyses the hydrolysis of sucrose into glucose and fructose.

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Q46. In frog, the surface of attachment of tongue is

1. pterygoid
2. palatine
3. sphenoid
4. hyoid apparatus

Answer: (d)

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Q47. Carbohydrases are missing from

1. Pancreatic juice
2. Intestinal juice
3. Gastric juice
4. Saliva

Answer: (c)

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Q48. Oxyntic cells are located in

1. Kidneys and secrete renin
2. Gastric epithelium and secrete pepsin
3. Islets of Langerhans
4. Gastric epithelium and secrete HCl

Answer: (d)

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Q49. What is common among amylase, renin and trypsin?

1. These are produced in stomach
2. These all are proteolytic enzymes
3. These all are proteins
4. These act at a pH lower than 7

Answer: (c)

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Q50. Which one of the following statements is true regarding digestion and absorption of food in humans?

1. Chylomicrons are small lipoprotein particles that are transported from intestine into blood capillaries.
2. Fructose and amino acids are absorbed through intestinal mucosa with the help of carrier ions like $Na^{+}$.
3. About 60% of starch is hydrolysed by salivary amylase in our mouth
4. Oxyntic cells in our stomach secrete the proenzyme pepsinogen.

Answer: (b)

Fructose and amino acids are absorbed through intestinal mucosa with the help of carrier ions like $Na^{+}$. Carbohydrates are absorbed as monosaccharides (simple sugars such as glucose, fructose, and galactose that cannot be further broken down by hydrolysis) or as disaccharides (such as sucrose, lactose, maltose, and dextrin that can be hydrolyzed to two monosaccharides).

These simpler molecules, however, must be obtained by the breaking down of polysaccharides, (complex carbohydrates) that contain many monosaccharides.

Chief among these is amylase, a starch that accounts for 20 percent of dietary carbohydrate.

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