Nokea
What is the main function of calcitonin, a hormone produced by the thyroid gland?
- A. Stimulate metabolism and heat production
- B. Increase calcium absorption from the intestines
- C. Enhance bone growth and development
- D. Lower blood calcium levels
Correct Answer: D
Rationale: Calcitonin is a hormone produced by the thyroid gland that primarily functions to lower blood calcium levels. It achieves this by inhibiting bone breakdown and promoting calcium excretion by the kidneys. Therefore, the correct answer is D as it reflects the main role of calcitonin in calcium homeostasis. Choices A, B, and C are incorrect as they do not align with the primary function of calcitonin. Calcitonin does not stimulate metabolism and heat production (Choice A), increase calcium absorption from the intestines (Choice B), or enhance bone growth and development (Choice C).
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Which of the following is a unit of work and energy?
- A. Pascal (Pa)
- B. Kilowatt-hour (kWh)
- C. Coulomb (C)
- D. Tesla (T)
Correct Answer: B
Rationale: The correct answer is 'B: Kilowatt-hour (kWh).' The kilowatt-hour is a unit commonly used to measure electricity consumption, representing energy usage over time. A Pascal (Pa) is a unit of pressure, Coulomb (C) is a unit of electric charge, and Tesla (T) is a unit of magnetic flux density. Therefore, the kilowatt-hour is the appropriate unit for measuring work and energy in this context.
In the context of cholesterol levels, LDL cholesterol is often referred to as:
- A. HDL or "good" cholesterol.
- B. LDL or "bad" cholesterol.
- C. Total cholesterol, encompassing both LDL and HDL.
- D. VLDL, a type of triglyceride transported in the bloodstream.
Correct Answer: B
Rationale: LDL cholesterol is often referred to as "bad" cholesterol because high levels of LDL can lead to plaque buildup in the arteries, increasing the risk of heart disease and stroke. LDL cholesterol is considered harmful as it contributes to the formation of plaque in blood vessels, whereas HDL cholesterol helps remove LDL from the arteries. Choice A is incorrect because HDL is known as "good" cholesterol, which helps remove LDL cholesterol from the bloodstream. Choice C is incorrect as it refers to total cholesterol, which includes LDL, HDL, and other lipids. Choice D is incorrect as VLDL is a different type of lipoprotein that carries triglycerides and is not specifically related to LDL cholesterol.
Isotopes are variants of a single element that differ in:
- A. Having the same number of protons but varying numbers of neutrons
- B. Having the same number of neutrons but varying numbers of protons
- C. Having the same mass but different atomic numbers
- D. None of the above
Correct Answer: A
Rationale: Isotopes are variants of a single element that have the same number of protons, the defining characteristic of an element. They differ in the number of neutrons they possess, leading to isotopes having different atomic masses while retaining the same chemical properties. Choice B is incorrect because isotopes have the same number of neutrons and differ in the number of protons. Choice C is incorrect because isotopes have different masses due to varying numbers of neutrons, not different atomic numbers. Choice D is incorrect as isotopes do differ in the number of neutrons they possess.
What is the term for the tiny particles that make up atoms?
- A. Protons
- B. Electrons
- C. Neutrons
- D. Subatomic particles
Correct Answer: D
Rationale: The correct answer is 'Subatomic particles.' Subatomic particles are the tiny components that constitute atoms, including protons, neutrons, and electrons. Protons and neutrons are located in the nucleus of an atom, while electrons revolve around the nucleus. Choices A, B, and C specifically refer to individual subatomic particles but do not encompass the complete range of particles within an atom.
What is the main difference between white and brown adipose tissue?
- A. Location only
- B. Function and energy metabolism
- C. Color only
- D. Both white and brown have the same function
Correct Answer: B
Rationale: The main difference between white and brown adipose tissue lies in their function and energy metabolism. White adipose tissue is primarily involved in energy storage, while brown adipose tissue is specialized for energy expenditure and thermogenesis. This functional disparity is the key dissimilarity between white and brown adipose tissue, rather than just their location or color. Choice A is incorrect because the difference is not only in location but also in function. Choice C is incorrect as color is not the defining factor in their distinction. Choice D is incorrect as white and brown adipose tissues serve different functions in the body.