Nokea
Which statement explains why elements in the same group of the Periodic Table have similar chemical properties?
- A. They have different numbers of protons.
- B. They have the same number of neutrons.
- C. They have the same number of electron shells.
- D. They have the same number of outer-shell electrons.
Correct Answer: D
Rationale: Correct Answer: D
Rationale:
1. Elements in the same group have similar outer electron configurations.
2. Outer-shell electrons determine chemical properties.
3. Having the same number of outer-shell electrons leads to similar chemical behaviors.
4. This is due to similar valence electron interactions in chemical reactions.
Summary:
A: Incorrect. Protons do not determine chemical properties in the same group.
B: Incorrect. Neutrons do not affect chemical properties in the same group.
C: Incorrect. Having the same number of electron shells does not guarantee similar chemical properties.
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Which of the following stimulates the release of parathyroid hormone?
- A. TSH from the posterior pituitary gland
- B. high levels of calcium in the blood
- C. calcitonin from the anterior pituitary gland
- D. low levels of calcium in the blood
Correct Answer: D
Rationale: The correct answer is D: low levels of calcium in the blood. Parathyroid hormone is released in response to low blood calcium levels to help increase calcium levels by promoting its release from bones and enhancing its absorption in the intestines. This response helps maintain calcium homeostasis. TSH from the posterior pituitary gland (choice A) is not related to parathyroid hormone release. High levels of calcium in the blood (choice B) would not stimulate parathyroid hormone release as it is released in response to low calcium levels. Calcitonin from the anterior pituitary gland (choice C) actually works in opposition to parathyroid hormone by promoting calcium deposition in bones and decreasing blood calcium levels.
Virtually all of the protein or amino acid-based hormones exert their effects through intracellular ________.
- A. ions
- B. deactivators
- C. nucleotides
- D. second messengers
Correct Answer: D
Rationale: The correct answer is D: second messengers. Protein or amino acid-based hormones are unable to pass through the cell membrane due to their large size and hydrophilic nature. Therefore, they bind to specific receptors on the cell surface, triggering a series of events that lead to the production of second messengers inside the cell. These second messengers, such as cyclic AMP or calcium ions, then transmit the hormonal signal to the target cell's interior to initiate a physiological response. Choices A, B, and C are incorrect because protein or amino acid-based hormones do not directly exert their effects through ions, deactivators, or nucleotides intracellularly.
The inability to produce ADH causes ______.
- A. diabetes mellitus.
- B. uterine contractions.
- C. diabetes insipidus.
- D. decreased urine volume.
Correct Answer: C
Rationale: The correct answer is C: diabetes insipidus. The inability to produce ADH (antidiuretic hormone) results in diabetes insipidus, characterized by excessive thirst and urination. ADH plays a crucial role in regulating water retention by the kidneys. Without ADH, the kidneys are unable to concentrate urine, leading to increased urine output and dehydration.
A: Diabetes mellitus is not caused by the inability to produce ADH. It is a condition characterized by high blood sugar levels due to insufficient insulin production or ineffective use of insulin.
B: Uterine contractions are not related to the production of ADH. Uterine contractions are primarily controlled by hormones such as oxytocin during labor.
D: Decreased urine volume is the opposite of what occurs in diabetes insipidus. In this condition, there is an increase in urine volume due to the inability to concentrate urine.
Which of the following is NOT true of Cushing syndrome?
- A. trunk (torso) becomes obese
- B. basic blood pH
- C. moon-shaped face
- D. hyposecretion of adrenal cortex hormones.
Correct Answer: D
Rationale: Step-by-step rationale:
1. Cushing syndrome is characterized by hypersecretion of adrenal cortex hormones, not hyposecretion.
2. Option D states hyposecretion, which is incorrect for Cushing syndrome.
3. Trunk obesity, moon-shaped face, and alkalosis (basic blood pH) are characteristic features of Cushing syndrome.
4. Thus, option D is the correct answer because it is not a true characteristic of Cushing syndrome.
Summary:
Option D is incorrect because Cushing syndrome is associated with hypersecretion of adrenal cortex hormones, not hyposecretion. Options A, B, and C are true characteristics of Cushing syndrome, making them incorrect choices.
Antidiuretic hormone (ADH) and oxytocin:
- A. are secreted by the neurohypophysis.
- B. are mineralocorticoids.
- C. are secreted by the islets of Langerhans.
- D. stimulate the kidney to excrete Na+ and water.
Correct Answer: A
Rationale: Step-by-step rationale for choice A being correct:
1. ADH and oxytocin are peptide hormones.
2. They are synthesized in the hypothalamus.
3. They are transported and stored in the neurohypophysis.
4. Upon stimulation, they are released from the neurohypophysis.
5. Therefore, both ADH and oxytocin are indeed secreted by the neurohypophysis.
Summary of why other choices are incorrect:
B: ADH and oxytocin are not mineralocorticoids; they regulate water balance and uterine contractions, respectively.
C: Islets of Langerhans secrete insulin and glucagon, not ADH or oxytocin.
D: ADH promotes water reabsorption in the kidneys, opposite to excreting Na+ and water.