Nokea
The enzyme amylase breaks down?
- A. Carbohydrates
- B. Proteins
- C. Fats
Correct Answer: A
Rationale: The correct answer is A: Carbohydrates. Amylase is an enzyme that specifically breaks down carbohydrates, such as starch and glycogen, into simpler sugars like glucose. It does this by catalyzing the hydrolysis of alpha-1,4-glycosidic linkages in polysaccharides. Proteins are broken down by protease enzymes, not amylase. Fats are broken down by lipase enzymes. Choice D is incomplete and does not provide a relevant option.
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In relation to the molecular mechanism of action of sympathomimetics, the following is CORRECT:
- A. Beta receptor stimulation increases c-GMP
- B. Alpha 2 receptor stimulation stimulates adenyl cyclase
- C. Alpha 2 receptor stimulation increases c-AMP
- D. Alpha 1 receptor stimulation releases IP3 and DAG
Correct Answer: D
Rationale: The correct answer is D: Alpha 1 receptor stimulation releases IP3 and DAG. When alpha 1 receptors are stimulated by sympathomimetics, they activate G-proteins which then stimulate phospholipase C. Phospholipase C cleaves phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol trisphosphate (IP3) and diacylglycerol (DAG). IP3 triggers the release of calcium from intracellular stores, leading to smooth muscle contraction, while DAG activates protein kinase C to initiate various cellular responses. Choices A, B, and C are incorrect because beta receptor stimulation increases cAMP, alpha 2 receptor stimulation inhibits adenyl cyclase leading to decreased cAMP levels, and alpha 2 receptor stimulation does not increase cAMP.
Which one of the following is NOT typical of the changes that follow the binding of a hormone to its target cells:
- A. plasma membrane permeability changes
- B. cellular mutations occur
- C. enzymes are activated or inactivated
- D. mitosis is stimulated
Correct Answer: B
Rationale: The correct answer is B: cellular mutations occur. Hormone binding typically triggers signaling cascades that lead to cellular responses like changing plasma membrane permeability, activating/inactivating enzymes, or stimulating mitosis. Cellular mutations are not a direct result of hormone binding and are typically caused by external factors like radiation or chemicals. In this context, mutations do not happen as an immediate response to hormone binding. Therefore, option B is the correct choice. Plasma membrane permeability changes, enzyme activation/inactivation, and mitosis stimulation are all typical outcomes of hormone binding and subsequent signaling pathways.
In a patient with central diabetes insipidus, what will the administration of ADH during a water deprivation test result in?
- A. Decrease in body weight
- B. Decrease in blood pressure
- C. Increase in urinary output
- D. Increase in urine osmolality
Correct Answer: D
Rationale: In central diabetes insipidus, administering ADH during a water deprivation test will result in an increase in urine osmolality due to the kidneys' ability to concentrate urine in response to ADH.
Steatorrhoea occurs with all of the following EXCEPT:
- A. gastrinoma
- B. congenital defect in gastric lipase
- C. ileal disease with failure to reabsorb bile salts
- D. exocrine pancreatic disease
Correct Answer: B
Rationale: The correct answer is B: congenital defect in gastric lipase. Steatorrhoea is the presence of excess fat in the stool due to malabsorption. Gastrinoma (A), ileal disease (C), and exocrine pancreatic disease (D) can all lead to malabsorption of fats resulting in steatorrhoea. However, a congenital defect in gastric lipase does not directly affect fat absorption in the intestines, making it the exception in this scenario.
A calorie is:
- A. standard unit of heat energy necessary to raise the temperature of 1L of water 1° from 15-16°C
- B. standard unit of heat energy necessary to raise the temperature of 1gm of mercury 1° from 17-18°C
- C. the standard unit of heat energy necessary to raise the temperature of 1gm of water 1° from 17-18°C
- D. the standard unit of heat energy necessary to raise the temperature of 1gm of water 1° from 15-16°C
Correct Answer: D
Rationale: The correct answer is D: the standard unit of heat energy necessary to raise the temperature of 1gm of water 1° from 15-16°C. This is because a calorie is defined as the amount of heat energy required to raise the temperature of 1 gram of water by 1 degree Celsius. This definition aligns perfectly with choice D. Choices A, B, and C are incorrect because they involve raising the temperature of different substances (1L of water, 1gm of mercury, and 1gm of water) by 1 degree Celsius over different temperature ranges (15-16°C, 17-18°C), which do not match the standard definition of a calorie.