Anatomy HESI A2 Practice Test

Correct Answer: B

Rationale: The correct answer is B: To speed up chemical reactions. Enzymes act as biological catalysts that accelerate chemical reactions by lowering the activation energy required for the reactions to occur. They do not produce energy (choice A), transport molecules (choice C), or repair tissues (choice D). Enzymes specifically facilitate reactions without being consumed in the process, making them crucial for various metabolic pathways in the body.

Correct Answer: B

Rationale: The correct answer is B: To store and concentrate bile. The gallbladder acts as a reservoir for bile produced by the liver, which is then released into the small intestine to aid in digestion. Bile helps emulsify fats for better absorption. Choices A, C, and D are incorrect as the gallbladder does not produce bile (the liver does), detoxify harmful substances, or directly break down fats. The primary function of the gallbladder is to store and concentrate bile for efficient digestion.

Correct Answer: B

Rationale: The correct answer is B: Medulla oblongata. This brain part is located in the brainstem and controls vital functions such as heart rate and blood pressure. It contains the cardiovascular center which regulates these functions through autonomic nervous system pathways. The other choices (A: Cerebellum, C: Hypothalamus, D: Pons) do not have direct control over heart rate and blood pressure regulation. The cerebellum is mainly responsible for motor coordination, the hypothalamus regulates body temperature, hunger, and thirst, and the pons is involved in sleep and arousal. Thus, the medulla oblongata is the correct choice for regulating heart rate and blood pressure.

Correct Answer: B

Rationale: The primary function of the alveoli in the lungs is to exchange oxygen and carbon dioxide. This process occurs through diffusion, where oxygen moves from the alveoli into the bloodstream, and carbon dioxide moves from the bloodstream into the alveoli to be exhaled. This exchange is essential for oxygenating the blood and removing carbon dioxide, maintaining proper gas exchange in the body. Why the other choices are incorrect: A: Alveoli do play a role in removing carbon dioxide, but their primary function is the exchange of oxygen and carbon dioxide. C: While alveoli do transport oxygen to the bloodstream, they also exchange carbon dioxide, making this choice incomplete. D: Alveoli do not filter blood; their main function is gas exchange in the lungs.

Correct Answer: B

Rationale: The correct answer is B: To speed up chemical reactions. Enzymes act as biological catalysts that accelerate chemical reactions by lowering the activation energy required for the reactions to occur. They do not produce energy (choice A), transport molecules (choice C), or repair tissues (choice D). Enzymes specifically facilitate reactions without being consumed in the process, making them crucial for various metabolic pathways in the body.