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. What is the role of enzymes in the body?
- A. To produce energy
- B. To speed up chemical reactions
- C. To transport molecules
- D. To repair tissues
Correct answer: B
Rationale: Enzymes are biological catalysts that facilitate and speed up chemical reactions in the body. They do not produce energy but enable various processes such as digestion and metabolism by lowering the activation energy required for reactions to occur. Choice A is incorrect because enzymes do not produce energy themselves but assist in energy production through reactions. Choice C is incorrect as enzymes do not primarily function in transporting molecules, although some may have a role in specific transport processes. Choice D is incorrect as the primary role of enzymes is not to repair tissues, but rather to catalyze biochemical reactions.
3. What is the function of the medulla oblongata in the brain?
- A. To control breathing and heart rate
- B. To regulate body temperature
- C. To coordinate voluntary movements
- D. To process sensory information
Correct answer: A
Rationale: The correct answer is A: To control breathing and heart rate. The medulla oblongata is a vital part of the brainstem responsible for regulating essential functions such as breathing, heart rate, and blood pressure. These functions are crucial for maintaining life, and the medulla oblongata plays a key role in ensuring the body's survival. Choices B, C, and D are incorrect because regulating body temperature is primarily controlled by the hypothalamus, coordinating voluntary movements is associated with the cerebellum and motor cortex, and processing sensory information is related to the thalamus and sensory cortex, not the medulla oblongata.
4. Which structure is responsible for carrying oxygen to the cells?
- A. Hemoglobin
- B. Plasma
- C. Platelets
- D. Red blood cells
Correct answer: A
Rationale: Hemoglobin, located in red blood cells, is responsible for binding to oxygen in the lungs and transporting it to tissues throughout the body. Red blood cells contain hemoglobin, making them the primary carrier of oxygen to cells. Hemoglobin is the correct answer because it is the protein within red blood cells that directly binds to oxygen for transport. Plasma is the liquid component of blood and does not carry oxygen. Platelets are responsible for blood clotting and have no role in oxygen transport. While red blood cells do carry oxygen, it is specifically the hemoglobin within them that performs this function.
5. The motor cortex is essential for monitoring and controlling body movements. Where is the motor cortex located within the brain?
- A. Top, middle portion of the parietal lobe
- B. Back of the head
- C. Front portion of the parietal lobe
- D. Around the auditory cortex
Correct answer: C
Rationale: The motor cortex is located in the frontal portion of the brain, specifically in the precentral gyrus of the frontal lobe. It plays a crucial role in planning, controlling, and executing voluntary movements. Choice A, 'Top, middle portion of the parietal lobe,' is incorrect because the motor cortex is not located in the parietal lobe but rather in the frontal lobe. Choice B, 'Back of the head,' is incorrect as it refers to the occipital lobe, not where the motor cortex is situated. Choice D, 'Around the auditory cortex,' is incorrect as the motor cortex is not located around the auditory cortex but in the frontal lobe, as mentioned earlier.
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