Nokea
Starch is digested to maltose by the enzyme amylase. According to the 'lock and key' hypothesis, which is the 'key' and which is the 'lock'?
- A. key: amylase, lock: starch
- B. key: starch, lock: amylase
- C. key: maltose, lock: amylase
- D. key: amylase, lock: maltose
Correct Answer: A
Rationale: In the lock and key model, the enzyme (amylase) is the key that specifically binds to the substrate (starch), acting as the lock.
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The term used to describe the stomach's expansion to accommodate volume without any rise in intraluminal pressure is referred to as:
- A. Vomiting
- B. Activation of osmoreceptors
- C. Folding inward (invagination)
- D. Relaxation in response to stimulation (receptive relaxation)
Correct Answer: D
Rationale: Receptive relaxation allows the stomach to expand as food enters, mediated by the vagus nerve, without increasing pressure.
Which type of digestion breaks down pieces of food into small molecules?
- A. chemical digestion
- B. peristalsis digestion
- C. mechanical digestion
- D. absorption digestion
Correct Answer: A
Rationale: Chemical digestion uses enzymes to break food into small molecules.
Where are the osmoreceptors located?
- A. Kidney
- B. Hypothalamus
- C. Pituitary
- D. Liver
Correct Answer: B
Rationale: Osmoreceptors in the hypothalamus detect blood osmolarity changes.
The part of the stomach that meets the esophagus at the gastroesophageal sphincter is the:
- A. fundus
- B. cardia
- C. pylorus
- D. body
Correct Answer: B
Rationale: The cardia is the part of the stomach closest to the esophagus.
What is the name of the tube that carries food from the mouth to the stomach?
- A. Trachea
- B. Oesophagus
- C. Duodenum
- D. Food tube
Correct Answer: B
Rationale: The esophagus is the muscular tube that transports food from the mouth to the stomach. The trachea is for air, the duodenum is part of the small intestine, and 'food tube' is not a scientific term.