Nokea
What is the primary function of the liver?
- A. To produce bile, which aids in the digestion of fats
- B. To store energy in the form of glycogen
- C. To produce proteins that assist in blood clotting
- D. To detoxify harmful substances in the body
Correct Answer: D
Rationale: The primary function of the liver is to detoxify harmful substances in the body. While the liver does produce bile to aid in the digestion of fats, this is not its primary function. Bile is stored in the gallbladder and released into the small intestine for fat digestion. Storing energy in the form of glycogen is a function of the liver, but not its primary one. Glycogen serves as a reserve of glucose. Although the liver produces proteins that assist in blood clotting, such as fibrinogen and prothrombin, this is not its main function. These proteins play a crucial role in blood clotting to prevent excessive bleeding. Therefore, the primary role of the liver is to detoxify harmful substances by processing and removing toxins, drugs, alcohol, and other harmful substances from the bloodstream, thereby reducing their harmful effects.
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Which vitamin is crucial for calcium absorption and synthesized in the skin upon sun exposure?
- A. Vitamin A
- B. Vitamin C
- C. Vitamin D
- D. Vitamin E
Correct Answer: C
Rationale: The correct answer is Vitamin D. Vitamin D is essential for calcium absorption as it helps regulate calcium and phosphorus levels in the body. When the skin is exposed to sunlight, UVB rays convert a compound in the skin to vitamin D. This vitamin is vital for maintaining bone health and ensuring the overall calcium balance in the body. Choices A, B, and D are incorrect. Vitamin A is important for vision and immune function, Vitamin C is essential for collagen synthesis and immune function, and Vitamin E is an antioxidant that helps protect cells from damage by free radicals. However, none of these vitamins are primarily responsible for calcium absorption and synthesized in the skin upon sun exposure.
What does nuclear binding energy represent?
- A. Separate an electron from its atom
- B. Separate protons and neutrons within a nucleus
- C. Cause nuclear fission
- D. Induce nuclear fusion
Correct Answer: B
Rationale: Nuclear binding energy represents the energy required to hold protons and neutrons together within a nucleus. This energy is needed to overcome the electrostatic repulsion between positively charged protons and keep the nucleus stable. Choices A, C, and D are incorrect. Choice A relates to ionization energy, which is the energy required to remove an electron from an atom. Choices C and D refer to nuclear reactions (fission and fusion), which involve processes different from the concept of nuclear binding energy.
What is the involuntary muscle tissue found in the walls of blood vessels and organs like the stomach and intestines?
- A. Skeletal muscle
- B. Cardiac muscle
- C. Smooth muscle
- D. Striated muscle
Correct Answer: C
Rationale: Smooth muscle is the correct answer. It is the involuntary muscle tissue found in the walls of blood vessels and organs like the stomach and intestines. Smooth muscle is responsible for various involuntary movements in the body, such as peristalsis in the digestive system and regulating blood flow in blood vessels. Skeletal muscle is voluntary and attached to bones for movement. Cardiac muscle is specific to the heart and not found in blood vessel walls or organs like the stomach and intestines. Striated muscle refers to both skeletal and cardiac muscle due to their striped appearance under a microscope, but it does not specifically describe the involuntary muscle tissue in the walls of blood vessels and organs as asked in the question.
Which of the following equations represents a redox reaction?
- A. 2H2 + O2 → 2H2O
- B. Zn + 2HCl → ZnCl2 + H2
- C. 2NaCl → 2Na + Cl2
- D. CH4 + 2O2 → CO2 + 2H2O
Correct Answer: B
Rationale: A redox reaction involves the transfer of electrons between reactants. In option B, Zn loses electrons to form Zn2+ while H+ gains electrons to form H2. This exchange of electrons demonstrates a redox reaction, making choice B the correct answer. In options A, C, and D, there is no clear transfer of electrons between the reactants, indicating that they are not redox reactions. Option A represents a synthesis reaction, option C represents a decomposition reaction, and option D represents a combustion reaction. These types of reactions do not involve the transfer of electrons between reactants, unlike a redox reaction.
What is the primary function of the atrioventricular (AV) node within the heart?
- A. Generate the electrical impulse for contraction (pacemaker function)
- B. Transmit the electrical impulse from the atria to the ventricles, regulating the timing of contraction.
- C. Increase blood pressure within the ventricles during systole.
- D. Separate oxygenated and deoxygenated blood flow in the heart.
Correct Answer: B
Rationale: The correct answer is B: Transmit the electrical impulse from the atria to the ventricles, regulating the timing of contraction. The primary function of the atrioventricular (AV) node is to coordinate the transmission of electrical signals between the atria and the ventricles. It ensures proper timing between atrial and ventricular contractions, allowing for efficient blood pumping through the heart. Choice A is incorrect because the AV node does not generate the initial electrical impulse; that role is typically attributed to the sinoatrial (SA) node. Choice C is incorrect as the AV node does not directly influence blood pressure within the ventricles. Choice D is also incorrect as the separation of oxygenated and deoxygenated blood is primarily achieved by the anatomical structure of the heart (e.g., atria and ventricles) and not the AV node.