HESI A2
HESI A2 Anatomy and Physiology 2023
1. Which part of the brain is involved in the regulation of heart rate and breathing?
- A. Cerebrum
- B. Cerebellum
- C. Medulla oblongata
- D. Hypothalamus
Correct answer: C
Rationale: The correct answer is C: Medulla oblongata. The medulla oblongata, situated in the brainstem, plays a crucial role in regulating vital functions such as heart rate, breathing, and blood pressure. It serves as the control center for involuntary actions, ensuring the body's automatic functions work properly. Choices A, B, and D are incorrect because the cerebrum is primarily responsible for functions such as thinking, voluntary movements, and sensory processing; the cerebellum is involved in coordination, balance, and muscle control; and the hypothalamus regulates body temperature, thirst, hunger, and some aspects of the autonomic nervous system but not specifically heart rate and breathing.
2. Which cellular structure is responsible for energy production?
- A. Nucleus
- B. Mitochondria
- C. Ribosome
- D. Golgi apparatus
Correct answer: B
Rationale: Corrected Question: Mitochondria are organelles known as the powerhouses of the cell. They generate energy through cellular respiration, producing ATP, which is used for various cellular functions. This process is crucial for providing the energy necessary to fuel cellular activities and sustain life. The other choices, the nucleus, ribosome, and Golgi apparatus, are important cellular structures but are not directly responsible for energy production. The nucleus houses the cell's genetic material, the ribosome is involved in protein synthesis, and the Golgi apparatus is responsible for processing and packaging proteins.
3. Within the biological hierarchical system of organization, which of the following is least inclusive?
- A. phylum
- B. order
- C. kingdom
- D. species
Correct answer: D
Rationale: The correct answer is 'D: species.' In the biological hierarchical system of organization, a species is the least inclusive level. A species consists of organisms that share similar characteristics and can interbreed to produce fertile offspring. On the other hand, a phylum, order, and kingdom are more inclusive classifications that encompass multiple species. Phylum groups together related classes, order groups together related families, and kingdom groups together related phyla. Therefore, species is the least inclusive category within the biological hierarchical system.
4. What is the main function of the immune system?
- A. To produce hormones
- B. To protect the body from infections
- C. To remove waste products
- D. To regulate body temperature
Correct answer: B
Rationale: The main function of the immune system is to protect the body from infections by identifying and destroying pathogens like bacteria and viruses. It plays a crucial role in maintaining overall health and preventing illnesses. Choice A is incorrect because hormone production is primarily handled by the endocrine system, not the immune system. Choice C is incorrect as waste removal is mainly performed by the excretory system, not the immune system. Choice D is incorrect as regulating body temperature is primarily the role of the thermoregulatory system, not the immune system.
5. Choose the meaning of the word rationale in the following sentence: "Step-by-step, the doctor explained the rationale for the treatment."
- A. Reasoning
- B. Prescription
- C. Procedure
- D. Necessity
Correct answer: A
Rationale: Corrected Question: In this context, the word 'rationale' refers to the underlying reasoning or justification for the treatment being explained step-by-step by the doctor. It pertains to the logical basis or thought process behind the chosen course of action. 'Prescription' (Choice B), 'Procedure' (Choice C), and 'Necessity' (Choice D) do not accurately capture the meaning of 'rationale' in the sentence provided.
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