The hormone that increases cardiac output by increasing both the rate and force of cardiac muscle contraction is

Correct Answer: B

Rationale: Cardiac output (CO) is the product of heart rate (HR) and stroke volume (SV), and adrenaline (epinephrine) enhances both by increasing HR and contractility. 'Adrenaline,' is correct because it acts via beta-adrenergic receptors to boost sympathetic stimulation, as per physiology texts like Guyton and Hall's Medical Physiology. 'Aldosterone,' regulates blood volume and pressure long-term, not directly affecting rate or force acutely. 'Angiotensin,' primarily causes vasoconstriction and aldosterone release, indirectly influencing CO. 'Thyroxin,' increases metabolism and HR over time but lacks adrenaline's immediate, dual impact on rate and force. Adrenaline's rapid action—seen in fight-or-flight responses—makes it uniquely suited to elevate CO by enhancing both parameters, distinguishing B as the precise answer, supported by its role in cardiovascular regulation during stress.

Correct Answer: B

Rationale: Polyunsaturated fatty acids (PUFAs) have multiple double bonds. 'Oleic acid,' is correct as the exception, a monounsaturated fatty acid with one double bond, per biochemistry (e.g., Harper's). 'Linoleic acid,' 'Arachidonic acid,' and 'Linolenic acid,' are PUFAs with multiple bonds, essential in diets. Oleic acid's single unsaturation contrasts with PUFAs' plurality, making B the precise answer.

Correct Answer: B

Rationale: The male urethra averages 20 cm, spanning prostatic, membranous, and spongy parts. '20 cm,' is correct, per anatomy texts like Netter, varying slightly (18-22 cm). '15 cm,' is short. '25 cm,' and '30 cm,' exceed typical length. The 20 cm standard reflects its path from bladder to external meatus, making B the accurate answer.

Correct Answer: B

Rationale: Vital capacity is the maximum air exhaled after full inhalation, about 4.8 L. 'Vital capacity,' is correct, per physiology (e.g., Tortora). 'Tidal volume,' is normal breath. 'Residual volume,' stays in lungs. 'Total lung capacity,' includes residual. Vital capacity's exhalable measure distinguishes B as the precise answer.

Correct Answer: C

Rationale: Long bones are longer than wide, in limbs. 'Carpals,' is correct as the exception, short bones in the wrist, per anatomy (e.g., Tortora). 'Humerus,' 'Femur,' and 'Tibia,' are long bones. Carpals' compact shape makes C the precise answer.