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What is the approximate composition of the air in the balloons?
- A. 16, 0.04, low
- B. 16, 4.5, high
- C. 21, 0.04, high
- D. 21, 4.5, low
Correct Answer: C
Rationale: The correct answer is C (21, 0.04, high). This composition represents the approximate percentage of oxygen (21%) and carbon dioxide (0.04%) in the air inside the balloons. Oxygen is a major component of the air we breathe, making up around 21% of the atmosphere. Carbon dioxide, on the other hand, is present in trace amounts, about 0.04%. The other choices are incorrect because they do not accurately represent the typical composition of air. Choice A has a low oxygen content and choice B has a high carbon dioxide content, both of which do not align with the usual composition of the air. Choice D also has a low oxygen content and high carbon dioxide content, making it incorrect.
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Steroids:
- A. are secreted by the adrenal medulla.
- B. include the glucocorticoids, mineralocorticoids, and androgens.
- C. stimulate the membranes of the target cells to produce the second chemical messenger, cAMP.
- D. are secreted by the pancreas.
Correct Answer: B
Rationale: The correct answer is B because steroids include glucocorticoids, mineralocorticoids, and androgens, which are hormones secreted by the adrenal cortex. Glucocorticoids regulate metabolism and immune response, mineralocorticoids regulate electrolyte balance, and androgens are male sex hormones.
Choice A is incorrect because steroids are secreted by the adrenal cortex, not the adrenal medulla. Choice C is incorrect because steroids act by entering the target cells and binding to intracellular receptors, not by stimulating second messengers like cAMP. Choice D is incorrect because steroids are not secreted by the pancreas; instead, the pancreas secretes hormones like insulin and glucagon.
Which glands are responsible for the regulation of calcium levels in the blood?
- A. Parathyroid and thyroid
- B. Adrenal medulla and pancreas
- C. Testes
- D. Parathyroid and thymus
Correct Answer: A
Rationale: The correct answer is A: Parathyroid and thyroid. The parathyroid glands produce parathyroid hormone (PTH), which regulates calcium levels in the blood by increasing calcium absorption from the intestines and releasing calcium from bones. The thyroid gland produces calcitonin, which helps lower blood calcium levels by promoting calcium deposition in bones. The other choices (B: Adrenal medulla and pancreas, C: Testes, D: Parathyroid and thymus) are incorrect because they do not play a direct role in regulating calcium levels in the blood.
What is the speed of the wave?
- A. 1.5cm/s
- B. 3.0cm/s
- C. 300 cm/s
- D. 600 cm/s
Correct Answer: D
Rationale: The correct answer is D: 600 cm/s. The speed of a wave is determined by the formula speed = frequency x wavelength. Given that the frequency and wavelength are constant, the only way to increase the speed is to increase the frequency or the wavelength. Since both frequency and wavelength are fixed, the speed can only be increased by increasing both. Choice D, 600 cm/s, is double the speed of choice C, 300 cm/s, which indicates that both frequency and wavelength have been doubled, leading to the correct answer. Choices A and B are too low to be correct, as they are not consistent with the principles of wave speed calculation.
Which of these is true of the endocrine system?
- A. secretes hormones that are transported to target cells by blood
- B. causes changes in metabolic activities
- C. effects are prolonged
- D. All of above are true.
Correct Answer: D
Rationale: Step 1: The endocrine system secretes hormones that travel through the bloodstream to specific target cells. (Choice A)
Step 2: These hormones regulate metabolic activities in the body. (Choice B)
Step 3: The effects of hormonal actions can last for an extended period, leading to prolonged effects. (Choice C)
Therefore, all the statements A, B, and C are true about the endocrine system, making choice D the correct answer. Other choices are incorrect as they do not encompass all aspects of the endocrine system's functions.
Jan, an insulin-dependent diabetic, was admitted to the emergency room with hypoglycemia after playing tennis all afternoon. The probable cause of this reaction was
- A. increased exercise level
- B. insufficient insulin dosage
- C. increased food intake
- D. increased glucagon production
Correct Answer: A
Rationale: Increased exercise can cause hypoglycemia in insulin-dependent diabetics by using up glucose in the body more quickly than the insulin can manage.