NUST NET Medical / Biological Sciences Biology Digestion — Set 3

NUST NET Medical / Biological Sciences Biology Digestion — Set 3

1. Question 1

   Q1. In the digestive system of ruminants, where does the initial microbial digestion of cellulose occur?

   • A) Rumen
   • B) Reticulum
   • C) Omasum
   • D) Abomasum

   Answer: Rumen

   Explanation: Microbial digestion occurs in the rumen; reticulum is involved but not for initial digestion. Omasum absorbs water.

2. Question 2

   Q2. A patient has a condition where the pyloric sphincter is always relaxed. What is the most likely effect on gastric emptying?

   • A) Gastric emptying is accelerated
   • B) Gastric emptying is delayed
   • C) Gastric emptying is unaffected
   • D) Gastric emptying becomes irregular

   Answer: Gastric emptying is accelerated

   Explanation: Pyloric sphincter controls gastric emptying; relaxation accelerates it. Contraction slows or stops emptying.

3. Question 3

   Q3. Which enzyme is NOT a product of the chief cells in the gastric glands?

   • A) Pepsinogen
   • B) Gastric amylase
   • C) Rennin
   • D) Lysozyme

   Answer: Gastric amylase

   Explanation: Gastric amylase is from chief cells in some species but not humans; pepsinogen is the main product.

4. Question 4

   Q4. What is the primary function of the brush border enzymes in the small intestine?

   • A) Protein synthesis
   • B) Carbohydrate digestion
   • C) Lipid absorption
   • D) Nucleic acid degradation

   Answer: Carbohydrate digestion

   Explanation: Brush border enzymes like lactase and sucrase digest carbohydrates; they are not involved in protein synthesis.

5. Question 5

   Q5. A person consumes a meal high in fat. Which hormone is primarily responsible for slowing gastric emptying in this scenario?

   • A) Gastrin
   • B) Secretin
   • C) CCK
   • D) GIP

   Answer: CCK

   Explanation: CCK slows gastric emptying in response to fat; it also stimulates gallbladder contraction.

6. Question 6

   Q6. In the liver, which type of cells are responsible for the storage of vitamin A?

   • A) Hepatocytes
   • B) Kupffer cells
   • C) Stellate cells
   • D) Endothelial cells

   Answer: Stellate cells

   Explanation: Stellate cells store vitamin A; hepatocytes are involved in metabolism, Kupffer cells in immune responses.

7. Question 7

   Q7. Which part of the digestive system is responsible for the majority of water absorption?

   • A) Small intestine
   • B) Large intestine
   • C) Stomach
   • D) Esophagus

   Answer: Small intestine

   Explanation: Small intestine absorbs most of the water; large intestine absorbs some but is not the majority.

8. Question 8

   Q8. A deficiency in which enzyme is associated with lactose intolerance?

   • A) Lactase
   • B) Sucrase
   • C) Maltase
   • D) Amylase

   Answer: Lactase

   Explanation: Lactase breaks down lactose; deficiency leads to intolerance. Sucrase and maltase digest other sugars.

9. Question 9

   Q9. What is the role of the gut-associated lymphoid tissue (GALT) in the digestive system?

   • A) Nutrient absorption
   • B) Immune function
   • C) Hormone production
   • D) Enzyme secretion

   Answer: Immune function

   Explanation: GALT is involved in immune responses; it includes Peyer's patches and other lymphoid tissues.

10. Question 10

    Q10. In which part of the digestive system does the majority of iron absorption occur?

    • A) Duodenum
    • B) Jejunum
    • C) Ileum
    • D) Colon

    Answer: Duodenum

    Explanation: Duodenum is the primary site for iron absorption; it is highly efficient here.

11. Question 11

    Q11. A patient has a condition that results in the inability to produce bile salts. What is the most likely effect on fat digestion?

    • A) Fat digestion is enhanced
    • B) Fat digestion is unaffected
    • C) Fat digestion is impaired
    • D) Fat digestion is completely halted

    Answer: Fat digestion is impaired

    Explanation: Bile salts emulsify fats; without them, fat digestion is impaired but not completely halted.

12. Question 12

    Q12. Which enzyme is responsible for the activation of trypsinogen to trypsin?

    • A) Enterokinase
    • B) Trypsin
    • C) Chymotrypsin
    • D) Carboxypeptidase

    Answer: Enterokinase

    Explanation: Enterokinase activates trypsinogen to trypsin; trypsin can then activate more trypsinogen.

13. Question 13

    Q13. What is the primary function of the Kupffer cells in the liver?

    • A) Detoxification
    • B) Phagocytosis
    • C) Protein synthesis
    • D) Glycogen storage

    Answer: Phagocytosis

    Explanation: Kupffer cells are macrophages; they are involved in phagocytosis, not detoxification or protein synthesis.

14. Question 14

    Q14. In the digestive system, what is the function of the migrating motor complex (MMC)?

    • A) To mix food with digestive enzymes
    • B) To propel food through the digestive tract during meals
    • C) To clear the stomach and small intestine between meals
    • D) To regulate blood flow to the digestive tract

    Answer: To clear the stomach and small intestine between meals

    Explanation: MMC clears the stomach and small intestine between meals; it is not directly involved in food propulsion during meals.

15. Question 15

    Q15. Which vitamin is produced by the bacteria in the large intestine?

    • A) Vitamin A
    • B) Vitamin K
    • C) Vitamin C
    • D) Vitamin D

    Answer: Vitamin K

    Explanation: Vitamin K is produced by bacteria in the large intestine; it is essential for blood clotting.

16. Question 16

    Q16. A condition that results in the inability to absorb vitamin B12 is most likely due to a deficiency in which factor?

    • A) Intrinsic factor
    • B) Extrinsic factor
    • C) Gastric amylase
    • D) Pancreatic lipase

    Answer: Intrinsic factor

    Explanation: Intrinsic factor is necessary for vitamin B12 absorption; it is produced by parietal cells in the stomach.

17. Question 17

    Q17. The enzyme responsible for breaking down triglycerides into fatty acids and glycerol is?

    • A) Amylase
    • B) Lipase
    • C) Trypsin
    • D) Chymotrypsin

    Answer: Lipase

    Explanation: Lipase breaks down triglycerides; amylase digests carbohydrates, trypsin and chymotrypsin digest proteins.

18. Question 18

    Q18. In the small intestine, which structure increases the surface area for absorption?

    • A) Villi
    • B) Microvilli
    • C) Peyer's patches
    • D) Both A and B

    Answer: Both A and B

    Explanation: Both villi and microvilli increase the surface area; villi are larger projections, microvilli are smaller.

19. Question 19

    Q19. The hormone gastrin stimulates the secretion of which substance?

    • A) Gastric juice
    • B) Pancreatic juice
    • C) Bile
    • D) Intestinal juice

    Answer: Gastric juice

    Explanation: Gastrin stimulates the secretion of gastric juice; it is produced by G cells in the stomach.

20. Question 20

    Q20. In the mouth, which enzyme initiates the digestion of starch?

    • A) Amylase
    • B) Lipase
    • C) Trypsin
    • D) Pepsin

    Answer: Amylase

    Explanation: Amylase breaks down starch; Lipase is for fats, Trypsin and Pepsin are for proteins in different parts of the digestive system.