Which statement explains why elements in the same group of the Periodic Table have similar chemical properties?

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.

Correct Answer: D

Rationale: The correct answer is D: permissiveness. Permissiveness is when one hormone enables another hormone to fully exert its effects. The rationale is as follows: 1. Permissiveness allows a hormone to work effectively only when another hormone is present to "permit" its action. 2. Assertiveness (A) and antagonism (B) do not involve the requirement of another hormone for full effect. 3. Synergism (C) involves two hormones working together for a greater effect, but they can still exert some effect individually. In summary, permissiveness is the only option where a hormone cannot exhibit its full effect without the presence of another hormone.

Correct Answer: D

Rationale: Osteitis fibrosa cystica is caused by an increase in the parathyroid hormone (PTH). Elevated PTH levels lead to increased calcium release from bones, resulting in bone resorption and cyst formation. Other choices (A) calcitonin, (B) ADH, and (C) growth hormone do not directly impact calcium metabolism and bone resorption like PTH does.

Correct Answer: C

Rationale: The correct answer is C because the release of hormones by the parathyroid glands is actually controlled by the levels of calcium in the blood, not by the pituitary gland. A: True - Parathyroid glands are four small yellowish brown ovoid glands. B: True - They lie in relation to the posterior border of thyroid lobes. D: True - The hormone produced by the parathyroid glands, parathyroid hormone (PTH), controls blood calcium levels by stimulating the release of calcium from bones and increasing the absorption of calcium from the intestines.

Correct Answer: d

Rationale: Rationale for Correct Answer (D): 1. Ca2+ ions do not directly break down ATP into ADP + inorganic phosphate at the sarcomere. 2. This breakdown occurs through the enzymatic action of myosin ATPase. 3. Ca2+ ions primarily bind to troponin to initiate muscle contraction by moving tropomyosin. 4. Ca2+ ions help expose active sites on actin, facilitating cross-bridge formation. Summary of Incorrect Choices: A. Correct - Ca2+ binds to troponin to move tropomyosin, not to uncover it. B. Correct - Ca2+ aids in exposing active sites on actin, not troponin. C. Correct - Ca2+ is stored in the sarcoplasmic reticulum, but it is released into the cytoplasm to trigger muscle contraction, not stored in the terminal cisternae.