Human Physiology – Digestion and Absorption Quiz - ICSE Class 11 Biology
Free practice quiz: Human Physiology – Digestion and Absorption (ICSE Class 11 Biology). 45 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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Which enzyme, secreted by the stomach, is responsible for the initial breakdown of proteins into smaller polypeptides?
- Trypsin
- Pepsin
- Chymotrypsin
- Carboxypeptidase
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Answer: B. Pepsin
Pepsin is the primary proteolytic enzyme in the stomach. It is secreted as an inactive zymogen, pepsinogen, which is activated by the acidic environment of the stomach. Pepsin breaks down proteins into smaller polypeptides.
Which vitamin is synthesized by the gut bacteria in the large intestine and absorbed by the host?
- Vitamin C
- Vitamin D
- Vitamin K
- Vitamin A
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Answer: C. Vitamin K
Certain species of bacteria in the large intestine, such as E. coli, synthesize vitamin K. This vitamin is then absorbed by the host and plays a crucial role in blood clotting.
The initial enzymatic breakdown of carbohydrates begins in the:
- Stomach
- Mouth
- Small intestine
- Large intestine
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Answer: B. Mouth
Saliva, produced in the mouth, contains salivary amylase (ptyalin), which begins the digestion of starch (a polysaccharide) into smaller polysaccharides and disaccharides.
The bacterial fermentation of undigested carbohydrates in the large intestine produces:
- Fatty acids and vitamins
- Amino acids and ammonia
- Ketone bodies and glucose
- Steroids and cholesterol
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Answer: A. Fatty acids and vitamins
Bacteria in the colon ferment undigested carbohydrates, producing short-chain fatty acids (like acetate, propionate, and butyrate), which can be absorbed and used as energy by the host, and also synthesize some vitamins, such as vitamin K and several B vitamins.
Which of the following is NOT a function of the liver in digestion?
- Production of bile
- Synthesis of plasma proteins
- Detoxification of absorbed substances
- Secretion of digestive enzymes
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Answer: D. Secretion of digestive enzymes
The liver's main digestive function is the production of bile, which aids in fat digestion and absorption. It also plays crucial roles in metabolism, detoxification of absorbed substances, and synthesis of plasma proteins. The secretion of major digestive enzymes is primarily a function of the pancreas and the small intestine.