Which of the following statements is NOT true about intravenous administration of drugs?

Correct Answer: C

Rationale: Intravenous (IV) administration delivers drugs directly into the bloodstream, bypassing certain processes. 'Bioavailability is 85%,' is correct as not true because IV achieves 100% bioavailability, not 85%, since there's no absorption barrier (e.g., Katzung's Pharmacology). 'First pass is avoided,' is true, skipping liver metabolism. 'No gastric manipulation,' is true, avoiding digestion. 'Desired blood concentration is achieved,' is true, allowing precise dosing. The 85% figure applies to routes like oral with losses, not IV's complete delivery, making C the false statement, grounded in pharmacokinetic principles.

Correct Answer: B

Rationale: A dependent variable is the outcome measured in research, affected by the independent variable. 'An effect variable,' is correct, aligning with experimental design (e.g., Campbell & Stanley), where it reflects changes (e.g., pain level post-treatment). 'Manipulated,' describes the independent variable. 'An intervention variable,' is also independent. 'An interdependent variable,' is not standard; variables may correlate, but dependent' means effected. B's focus on the variable being influenced matches its role, making it the precise answer.

Correct Answer: A

Rationale: Thoracic vertebrae (T1-T12) lack transverse foramina, present in cervical vertebrae for arteries. 'Transverse foramina,' is correct, per anatomy texts (e.g., Moore's Clinically Oriented Anatomy). 'Transverse processes,' articulate ribs. 'Pedicle,' and 'Spinous processes,' are standard features. The absence of transverse foramina in thoracic vertebrae makes A the accurate answer.

Correct Answer: B

Rationale: The SA node's pacemaker potential results from calcium influx via T-type channels, depolarizing cells. 'Calcium,' is correct, per cardiac physiology (e.g., Opie). 'Sodium,' contributes later in action potentials. 'Potassium,' hyperpolarizes. 'Magnesium,' is minor. Calcium's role in phase 4 depolarization makes B the precise answer.

Correct Answer: C

Rationale: Parathyroid hormone (PTH) increases plasma calcium by mobilizing bone calcium and renal reabsorption when levels drop. 'Parathyroid hormone,' is correct, per endocrinology texts like Williams, countering hypocalcemia. 'Calcitonin,' lowers calcium, opposing PTH. 'Aldosterone,' regulates sodium, not calcium directly. 'Adrenaline,' affects metabolism, not calcium. PTH's specific response to low calcium, restoring balance, makes C the precise answer, rooted in calcium homeostasis.