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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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How is power defined in terms of physics?
- A. The rate at which work is done
- B. The amount of force applied
- C. The distance an object travels
- D. The potential energy of an object
Correct Answer: A
Rationale: In physics, power is defined as the rate at which work is done, which refers to the amount of energy transferred or converted per unit time. Choice B, 'The amount of force applied,' is incorrect as power is related to work done, not just force. Choice C, 'The distance an object travels,' is not the definition of power but rather relates to displacement or distance. Choice D, 'The potential energy of an object,' is not the correct definition of power; potential energy is different from power. Therefore, the correct definition of power in physics is the rate at which work is done.
When a person pushes a box across the floor, which of the following forces is NOT doing work?
- A. The person's pushing force
- B. The normal force from the floor
- C. The gravitational force on the box
- D. The frictional force between the box and the floor
Correct Answer: B
Rationale: The normal force from the floor is perpendicular to the direction of motion of the box, so it does not contribute to the work being done. Work is only done by forces acting in the direction of motion of an object. In this case, the normal force is acting at a right angle to the motion, hence it does not perform any work on the box. The person's pushing force, the gravitational force, and the frictional force are all acting in the direction of motion of the box, so they contribute to the work being done in moving the box across the floor.
The Minimum Inhibitory Concentration (MIC) of an antibiotic refers to:
- A. The lowest concentration that kills bacteria
- B. The dose required for 50% bacterial inhibition
- C. The time it takes for an antibiotic to work
- D. The spectrum of bacteria the antibiotic targets
Correct Answer: B
Rationale: A) The lowest concentration that kills bacteria is known as the Minimum Bactericidal Concentration (MBC), not the Minimum Inhibitory Concentration (MIC). MIC is the lowest concentration of an antibiotic that inhibits visible growth of bacteria.
B) The MIC of an antibiotic is the concentration at which bacterial growth is inhibited by 50%. This concentration is used to determine the effectiveness of an antibiotic against a specific bacterium.
C) The time it takes for an antibiotic to work is not described by the MIC. MIC is a measure of concentration, not time.
D) The spectrum of bacteria the antibiotic targets is not defined by the MIC. The MIC value is specific to a particular antibiotic and bacterium, regardless of the spectrum of activity of the antibiotic.
What is the difference between mass and weight?
- A. Mass is the amount of matter in an object, whereas weight is the force of gravity acting on an object.
- B. Mass is a measure of inertia, whereas weight is a measure of the force of gravity acting on an object.
- C. Mass is measured in pounds, whereas weight is measured in kilograms.
- D. Mass is a vector quantity, whereas weight is a scalar quantity.
Correct Answer: A
Rationale: Mass is the amount of matter in an object and is a scalar quantity, whereas weight is the force of gravity acting on an object and is a vector quantity. Mass remains constant regardless of the location, while weight can vary depending on the strength of gravity at different locations. Answer choice A correctly defines the difference between mass and weight, making it the correct answer. Choice B is incorrect because mass is not a measure of inertia. Choice C is incorrect as mass is typically measured in kilograms, not pounds. Choice D is incorrect as mass is a scalar quantity, and weight is a vector quantity.
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.