what is the myelin sheath and what does it do
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ATI TEAS 7

ATI TEAS 7 science review

1. What is the myelin sheath and what does it do?

Correct answer: B

Rationale: The myelin sheath is a fatty substance that insulates some nerve fibers. It is made up of specialized cells that wrap around the axons of neurons, providing insulation and speeding up the transmission of nerve impulses. Choice A is incorrect as the myelin sheath is not a group of nerve cells but rather a substance that surrounds nerve fibers. Choice C is incorrect as the myelin sheath is not a fluid-filled cavity within the brain. Choice D is incorrect as the myelin sheath is not the junction between two neurons.

2. What is the primary function of white blood cells?

Correct answer: B

Rationale: The correct answer is B: "To fight infection." White blood cells are primarily responsible for fighting infections and foreign invaders in the body, making them a critical component of the immune system. Choice A, "To carry oxygen," is incorrect as red blood cells are responsible for oxygen transport. Choice C, "To transport nutrients," is incorrect as this function is mainly attributed to blood plasma and other specialized cells. Choice D, "To transport waste," is also incorrect as waste removal is primarily handled by the kidneys and the lymphatic system, not white blood cells.

3. Bile, a yellowish-green fluid, is stored in the gallbladder and released into the small intestine during digestion. What is the primary function of bile in digestion?

Correct answer: C

Rationale: The primary function of bile in digestion is to emulsify fats. Bile contains bile salts that help break down large fat globules into smaller droplets, increasing the surface area for enzymes to work on and aiding in the absorption of fats in the small intestine. Choices A, B, and D are incorrect because bile's main role is not to break down carbohydrates or proteins, nor to neutralize stomach acid; rather, it primarily assists in the digestion and absorption of fats through emulsification.

4. Consider the graph representing a botanist's data on root growth. What is the independent variable?

Correct answer: C

Rationale: The independent variable is the factor that is intentionally changed or manipulated by the researcher. In this case, light exposure is the independent variable because it is being controlled and tested to observe its effect on root growth. Choices A, B, and D are not the independent variable in this scenario. Temperature, root tissue, and root length are likely dependent variables that could be influenced by the changes in light exposure.

5. What is the purpose of an electrocardiogram?

Correct answer: B

Rationale: An electrocardiogram (ECG or EKG) is used to measure and display the heart's rate and rhythm. It provides valuable information about the electrical activity of the heart, allowing healthcare providers to assess the heart's health, detect abnormalities in the heart's rhythm, and diagnose various cardiac conditions. Choices A, C, and D are incorrect. Choice A is incorrect because an ECG does not indicate the rate of blood flow but rather focuses on the heart's electrical activity. Choice C is incorrect because identifying a person's blood group type is typically done through blood typing tests, not ECG. Choice D is incorrect because determining cell type in a blood sample is unrelated to the purpose of an ECG.

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