Nokea
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.
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Which organ produces insulin, a hormone responsible for regulating blood sugar levels?
- A. Parathyroid gland
- B. Pancreas
- C. Thymus gland
- D. Ovaries
Correct Answer: B
Rationale: Insulin is a hormone produced by the pancreas. Beta cells located in the islets of Langerhans within the pancreas are responsible for insulin production. Insulin plays a crucial role in regulating blood sugar levels by promoting the uptake of glucose into cells, thereby maintaining blood sugar levels within a normal range. Choices A, C, and D are incorrect because the parathyroid gland is primarily involved in regulating calcium levels, the thymus gland is involved in immune function, and the ovaries are involved in reproductive functions, not insulin production for blood sugar regulation.
What is the formula to calculate acceleration?
- A. Acceleration = Mass/Force
- B. Acceleration = Force/Mass
- C. Acceleration = Time/Distance
- D. Acceleration = Time Change in Velocity
Correct Answer: D
Rationale: Acceleration is defined as the rate of change of velocity with respect to time. The correct formula to calculate acceleration is Acceleration = Time Change in Velocity. This formula specifically represents how much an object's velocity changes over a specified time period, providing a measure of the object's speed change rate. Choices A and B are incorrect as they do not represent the relationship between acceleration and time change in velocity. Choice C is incorrect as it involves time and distance, which are not directly related to acceleration.
Which of the following factors would NOT affect the solubility of a solid solute in a liquid solvent?
- A. Temperature
- B. Pressure
- C. Particle size
- D. Nature of the solute and solvent
Correct Answer: B
Rationale: Pressure does not typically affect the solubility of a solid solute in a liquid solvent. Solubility is primarily influenced by factors such as temperature, particle size, and the nature of the solute and solvent. Increasing pressure generally has a minimal effect on the solubility of solids in liquids. The impact of pressure on solubility is more significant for gases in liquids rather than solids in liquids. Therefore, option B is the correct answer. Options A, C, and D directly impact the solubility of a solid solute in a liquid solvent. Temperature affects the solubility as it changes the kinetic energy of particles, particle size can impact the surface area available for interaction between solute and solvent, and the nature of the solute and solvent influences their intermolecular interactions and compatibility.
Immunoglobulin G (IgG) is the most abundant antibody type, responsible for:
- A. Immediate allergic reactions
- B. Neutralizing toxins and viruses
- C. Activating other immune cells
- D. Protecting newborns from infections
Correct Answer: B
Rationale: Immunoglobulin G (IgG) is indeed the most prevalent antibody type in the blood and tissue fluids. Its primary functions include neutralizing toxins and viruses, promoting phagocytosis, and activating the complement system. IgG plays a crucial role in long-term immunity and provides passive immunity to newborns by crossing the placenta, safeguarding them from infections. Immediate allergic reactions are mainly mediated by IgE, not IgG. While IgM is known for activating other immune cells, IgG focuses on other key functions within the immune response, such as neutralizing pathogens and enhancing phagocytosis. Therefore, the correct answer is B, as IgG is primarily involved in neutralizing toxins and viruses, rather than the other options presented.
Which property of a substance refers to its ability to be hammered or pressed into thin sheets without breaking?
- A. Malleability
- B. Ductility
- C. Viscosity
- D. Conductivity
Correct Answer: A
Rationale: Malleability is the correct answer as it is the property of a substance that allows it to be hammered or pressed into thin sheets without breaking. This property is crucial for materials like metals that need to be shaped without breaking. Ductility, on the other hand, refers to the ability of a substance to be drawn into thin wires, not hammered into sheets. Viscosity is a measure of a fluid's resistance to flow, indicating its thickness or thinness, and is unrelated to the ability to be hammered. Conductivity, on the other hand, refers to a substance's ability to conduct electricity or heat, which is not related to its ability to be hammered or pressed into thin sheets.