1. Which enzyme initiates the breakdown of carbohydrates in the mouth?
a) Amylase
b) Lipase
c) Pepsin
d) Trypsin
Answer: a) Amylase
Explanation: Amylase is an enzyme present in saliva that begins the breakdown of starches (carbohydrates) into simpler sugars.
2. Where is pepsinogen activated into pepsin?
a) Small intestine
b) Stomach
c) Large intestine
d) Pancreas
Answer: b) Stomach
Explanation: Pepsinogen is secreted by the stomach lining and is activated into pepsin in the acidic environment of the stomach, where it begins the breakdown of proteins.
3. Which enzyme is responsible for the breakdown of proteins in the stomach?
a) Amylase
b) Pepsin
c) Lactase
d) Lipase
Answer: b) Pepsin
Explanation: Pepsin is a protease enzyme that breaks down proteins into peptides in the acidic environment of the stomach.
4. Which of the following is the primary enzyme involved in the digestion of fats?
a) Amylase
b) Lipase
c) Trypsin
d) Sucrase
Answer: b) Lipase
Explanation: Lipase is responsible for the breakdown of fats into fatty acids and glycerol, primarily in the small intestine.
5. What is the function of lactase in the digestive system?
a) Breaking down starch into glucose
b) Breaking down proteins into amino acids
c) Breaking down lactose into glucose and galactose
d) Breaking down lipids into fatty acids
Answer: c) Breaking down lactose into glucose and galactose
Explanation: Lactase is an enzyme that helps digest lactose, the sugar found in milk, into its component sugars, glucose and galactose.
6. Which enzyme breaks down the sugar sucrose into glucose and fructose?
a) Maltase
b) Sucrase
c) Lactase
d) Amylase
Answer: b) Sucrase
Explanation: Sucrase is the enzyme that breaks down sucrose (table sugar) into glucose and fructose.
7. Which enzyme is secreted by the pancreas to aid in protein digestion in the small intestine?
a) Pepsin
b) Amylase
c) Trypsin
d) Lipase
Answer: c) Trypsin
Explanation: Trypsin is a protease secreted by the pancreas into the small intestine, where it further breaks down proteins into smaller peptides and amino acids.
8. Which of the following enzymes is responsible for breaking down starch into maltose?
a) Amylase
b) Lipase
c) Maltase
d) Lactase
Answer: a) Amylase
Explanation: Amylase breaks down starch (a polysaccharide) into maltose (a disaccharide) in the mouth and small intestine.
9. The enzyme responsible for the digestion of RNA and DNA in the small intestine is:
a) Amylase
b) Deoxyribonuclease
c) Nuclease
d) Pepsin
Answer: c) Nuclease
Explanation: Nuclease enzymes (such as ribonuclease and deoxyribonuclease) break down RNA and DNA into nucleotides in the small intestine.
10. What is the role of bile in fat digestion?
a) It emulsifies fats
b) It breaks down proteins
c) It neutralizes stomach acid
d) It digests carbohydrates
Answer: a) It emulsifies fats
Explanation: Bile, produced by the liver and stored in the gallbladder, emulsifies fats, making them easier for lipase to break down into fatty acids and glycerol.
11. Which of the following is a pancreatic enzyme that digests carbohydrates?
a) Amylase
b) Trypsin
c) Lipase
d) Pepsin
Answer: a) Amylase
Explanation: Pancreatic amylase is secreted into the small intestine, where it continues the breakdown of carbohydrates into smaller sugar molecules.
12. Which enzyme activates trypsinogen into trypsin?
a) Chymotrypsin
b) Enterokinase
c) Pepsin
d) Amylase
Answer: b) Enterokinase
Explanation: Enterokinase, secreted by the cells of the duodenum, activates trypsinogen into trypsin, which is essential for protein digestion.
13. What is the primary function of maltase in the digestive system?
a) To break down maltose into glucose
b) To break down starch into maltose
c) To emulsify fats
d) To break down proteins
Answer: a) To break down maltose into glucose
Explanation: Maltase is responsible for breaking down maltose, a disaccharide, into two molecules of glucose.
14. Which enzyme is responsible for converting pepsinogen into pepsin in the stomach?
a) Pepsin
b) Hydrochloric acid
c) Gastrin
d) Enterokinase
Answer: b) Hydrochloric acid
Explanation: The acidic environment of the stomach, created by hydrochloric acid, activates pepsinogen into pepsin, which begins protein digestion.
15. What role does chymotrypsin play in digestion?
a) Breaking down starches
b) Breaking down proteins
c) Breaking down fats
d) Breaking down nucleic acids
Answer: b) Breaking down proteins
Explanation: Chymotrypsin is a protease enzyme that helps break down proteins into smaller peptides in the small intestine.
16. Which of the following enzymes is involved in the breakdown of triglycerides in the small intestine?
a) Amylase
b) Lipase
c) Lactase
d) Trypsin
Answer: b) Lipase
Explanation: Lipase is the enzyme responsible for breaking down triglycerides (a type of fat) into fatty acids and glycerol in the small intestine.
17. Which enzyme is responsible for the digestion of starches in the mouth?
a) Amylase
b) Lactase
c) Lipase
d) Trypsin
Answer: a) Amylase
Explanation: Amylase is present in the saliva and begins the digestion of starches into smaller sugars like maltose.
18. What is the role of the enzyme sucrase in digestion?
a) Breaking down lactose
b) Breaking down sucrose
c) Breaking down starches
d) Breaking down fats
Answer: b) Breaking down sucrose
Explanation: Sucrase breaks down the disaccharide sucrose into glucose and fructose in the small intestine.
19. Which enzyme aids in the digestion of proteins and is secreted by the pancreas?
a) Amylase
b) Lipase
c) Trypsin
d) Sucrase
Answer: c) Trypsin
Explanation: Trypsin is a pancreatic enzyme that breaks down proteins into smaller peptides in the small intestine.
20. The final product of carbohydrate digestion in the human digestive system is:
a) Amino acids
b) Glucose
c) Fatty acids
d) Nucleotides
Answer: b) Glucose
Explanation: Carbohydrates are broken down into simple sugars, primarily glucose, which can be absorbed by the body.
21. Which of the following enzymes is secreted by the small intestine to break down maltose?
a) Sucrase
b) Maltase
c) Lactase
d) Peptidase
Answer: b) Maltase
Explanation: Maltase breaks down maltose into glucose in the small intestine.
22. Where does protein digestion begin in the human digestive system?
a) Stomach
b) Mouth
c) Small intestine
d) Large intestine
Answer: a) Stomach
Explanation: Protein digestion begins in the stomach with the action of pepsin, which breaks down proteins into peptides.
23. The enzyme that breaks down proteins in the stomach is activated by:
a) Amylase
b) Pepsinogen
c) Trypsin
d) Bile
Answer: b) Pepsinogen
Explanation: Pepsinogen is activated into pepsin by hydrochloric acid in the stomach, where it breaks down proteins.
24. Which enzyme is responsible for breaking down fats into fatty acids and glycerol?
a) Lipase
b) Amylase
c) Pepsin
d) Maltase
Answer: a) Lipase
Explanation: Lipase is the enzyme responsible for breaking down triglycerides (fats) into fatty acids and glycerol during digestion.
25. What is the role of bile salts in digestion?
a) Breaking down carbohydrates
b) Breaking down proteins
c) Emulsifying fats
d) Activating enzymes
Answer: c) Emulsifying fats
Explanation: Bile salts are responsible for emulsifying large fat molecules, increasing the surface area for lipase to act upon them.
26. Which of the following is a digestive enzyme that acts on proteins in the stomach?
a) Pepsin
b) Trypsin
c) Amylase
d) Lipase
Answer: a) Pepsin
Explanation: Pepsin is a protease enzyme that acts in the acidic stomach environment to break down proteins into peptides.
27. What does the enzyme lipase primarily break down?
a) Proteins
b) Carbohydrates
c) Fats
d) Nucleic acids
Answer: c) Fats
Explanation: Lipase is the enzyme that breaks down fats into fatty acids and glycerol, aiding in digestion.
28. Which enzyme is responsible for breaking down proteins in the small intestine after being activated?
a) Pepsin
b) Trypsin
c) Amylase
d) Sucrase
Answer: b) Trypsin
Explanation: Trypsin, activated from trypsinogen in the small intestine, continues the digestion of proteins into peptides.
29. Which enzyme in the stomach breaks down nucleic acids?
a) Amylase
b) Deoxyribonuclease
c) Nuclease
d) Lipase
Answer: c) Nuclease
Explanation: Nuclease enzymes break down nucleic acids into nucleotides in the digestive system.
30. What is the role of the enzyme peptidase in digestion?
a) Breaking down starch
b) Breaking down proteins into amino acids
c) Breaking down lipids
d) Breaking down sugars
Answer: b) Breaking down proteins into amino acids
Explanation: Peptidase enzymes break down peptides into amino acids in the final stages of protein digestion in the small intestine.
