Nokea
Which of the following vitamins is not stored in the liver?
- A. C
- B. D
- C. B12
- D. A
Correct Answer: A
Rationale: The correct answer is A: Vitamin C. Vitamin C is water-soluble and not stored in the liver. It gets absorbed in the intestines and any excess is excreted in the urine. Vitamin D (choice B) is fat-soluble and stored in the liver. Vitamin B12 (choice C) is also stored in the liver. Vitamin A (choice D) is fat-soluble and stored in the liver as well. Thus, the correct answer is A as it is the only water-soluble vitamin among the options.
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Bile salts:
- A. Protein emulsifier.
- B. Are needed by pancreatic amylase for carbohydrate digestion.
- C. Are produced by the liver from cholesterol.
- D. Increase lipid surface tension.
Correct Answer: C
Rationale: The correct answer is C: Bile salts are produced by the liver from cholesterol.
Rationale:
1. Bile salts aid in the emulsification and digestion of fats, not proteins (A).
2. Pancreatic amylase is responsible for carbohydrate digestion, not bile salts (B).
3. The liver synthesizes bile salts from cholesterol to facilitate fat digestion and absorption (C).
4. Bile salts reduce lipid surface tension to form micelles, aiding in fat digestion, rather than increasing it (D).
Amylase could be found in all of these areas except which one?
- A. mouth
- B. stomach
- C. duodenum
- D. pancreas
Correct Answer: B
Rationale: The correct answer is B (stomach) because amylase is an enzyme that breaks down carbohydrates, and it is primarily found in the mouth and the small intestine (duodenum and pancreas). In the mouth, salivary amylase begins the digestion of starches. In the small intestine, pancreatic amylase continues this process. The stomach, however, is not a site for amylase secretion but rather secretes pepsin for protein digestion. Therefore, amylase is not found in the stomach. Choices A, C, and D are incorrect because amylase is indeed present in the mouth, duodenum, and pancreas, respectively.
The submucosa of the GIT
- A. Is important for protection
- B. Helps with absorption and secretion
- C. Contains an outer and inner layer
- D. Is between the serosa and muscularis externa
Correct Answer: B
Rationale: The submucosa of the GIT is rich in blood vessels, nerves, and lymphatic vessels, aiding in absorption and secretion of nutrients and fluids. The submucosa is not primarily responsible for protection (choice A). It does not contain distinct outer and inner layers (choice C). The submucosa is located between the mucosa and muscularis externa, not the serosa (choice D). Therefore, the correct answer is B as it aligns with the known functions and characteristics of the submucosa.
Salivary secretion:
- A. Starts digestion of carbohydrates.
- B. is under control of secretin hormone.
- C. Starts digestion of proteins.
- D. is highly acidic.
Correct Answer: A
Rationale: The correct answer is A because salivary secretion contains enzymes like amylase that start the digestion of carbohydrates in the mouth. This enzyme breaks down complex carbohydrates into simpler sugars. Choices B, C, and D are incorrect because salivary secretion is not directly controlled by secretin hormone, does not start the digestion of proteins, and is not highly acidic. Salivary secretion primarily aids in the initial breakdown of carbohydrates, preparing them for further digestion in the stomach and intestines.
Where does the majority of nutrient absorption occur in the digestive system?
- A. Mouth
- B. Stomach
- C. Small intestine
- D. Large intestine
Correct Answer: C
Rationale: The majority of nutrient absorption occurs in the small intestine. Here's the rationale:
1. The small intestine is where most digestion and absorption of nutrients occur due to its large surface area.
2. Villi and microvilli in the small intestine increase the absorption surface for nutrients like carbohydrates, proteins, and fats.
3. Specific enzymes and bile are secreted in the small intestine to aid in the breakdown and absorption of nutrients.
4. The large intestine primarily absorbs water and electrolytes, not nutrients.
In summary, the mouth is mainly for mechanical digestion, the stomach primarily digests food, and the large intestine absorbs water, making the small intestine the correct choice for nutrient absorption.