HESI A2
HESI A2 Practice Test Anatomy and Physiology
1. Which type of blood cell is responsible for carrying oxygen?
- A. Red blood cells
- B. White blood cells
- C. Platelets
- D. Plasma cells
Correct answer: A
Rationale: The correct answer is A: Red blood cells. Red blood cells, also known as erythrocytes, are specialized cells designed to transport oxygen from the lungs to tissues and organs throughout the body. These cells contain hemoglobin, a protein that binds to oxygen molecules in the lungs and releases them in other parts of the body where oxygen is needed for cellular respiration. White blood cells (choice B) are part of the immune system, responsible for fighting infections. Platelets (choice C) are involved in blood clotting. Plasma cells (choice D) are a type of white blood cell that produces antibodies to help the body fight off infections.
2. Which of the following processes represents a different level of defense compared to the others?
- A. A low pH in the stomach
- B. Cilia present in the trachea
- C. Body cells recognizing a pathogen
- D. Mucus present in the nasal cavity
Correct answer: C
Rationale: Among the listed processes, low pH in the stomach, cilia in the trachea, and mucus in the nasal cavity serve as physical barriers that form the first line of defense against pathogens. These barriers work to block pathogens from entering the body. On the other hand, body cells recognizing a pathogen involves the immune response, which operates at a different level of defense. This process is part of the adaptive immune response, where the body's immune cells identify, target, and eliminate specific pathogens to provide a specialized defense after the pathogens have breached the physical barriers. Therefore, body cells recognizing a pathogen represent a different level of defense compared to the other listed processes.
3. Which vitamin is essential for maintaining healthy skin and vision?
- A. Vitamin C
- B. Vitamin A
- C. Vitamin D
- D. Vitamin K
Correct answer: B
Rationale: Vitamin A is the correct answer. It is essential for maintaining healthy skin and vision, especially in low-light conditions. Vitamin A helps in the production of retinal pigments necessary for vision in dim light and supports skin health by promoting cell turnover and repair. Choice A, Vitamin C, is important for the immune system and collagen production but is not specifically known for maintaining skin and vision health. Choice C, Vitamin D, is crucial for bone health and immune function but is not directly related to skin and vision health. Choice D, Vitamin K, is necessary for blood clotting and bone health but does not play a significant role in maintaining healthy skin and vision.
4. Which of the following describes the process of osmosis?
- A. Diffusion of solutes across a membrane
- B. Movement of water across a selectively permeable membrane
- C. Movement of gases across a membrane
- D. Active transport of ions across a membrane
Correct answer: B
Rationale: Osmosis is the process where water molecules move across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. This movement of water helps to equalize the concentration of solutes on both sides of the membrane. The correct description of osmosis is the movement of water across a selectively permeable membrane, making choice B the right answer. Choices A, C, and D are incorrect because osmosis specifically refers to the movement of water molecules, not solutes, gases, or ions across a membrane.
5. What is the primary function of the nervous system?
- A. To transmit signals and coordinate body activities
- B. To fight infections
- C. To produce hormones
- D. To regulate body temperature
Correct answer: A
Rationale: The primary function of the nervous system is to transmit signals and coordinate body activities. It controls and regulates body functions by sending and receiving signals between different parts of the body, enabling responses to internal and external stimuli. This intricate network allows for communication between the brain, spinal cord, and the rest of the body, ultimately facilitating movement, sensation, thoughts, and various bodily functions. Choices B, C, and D are incorrect as they do not represent the primary function of the nervous system. Fighting infections is primarily the role of the immune system, producing hormones is the function of the endocrine system, and regulating body temperature involves mechanisms of thermoregulation within the body, not directly controlled by the nervous system.
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