Nokea
What type of molecule forms the cell membrane and controls what enters and exits the cell?
- A. Proteins
- B. Carbohydrates
- C. Lipids
- D. Nucleic acids
Correct Answer: C
Rationale: The cell membrane is primarily composed of lipids, specifically phospholipids, which form a lipid bilayer. This lipid bilayer controls what enters and exits the cell, providing a barrier that is selectively permeable. While proteins are also important components of the cell membrane and play various roles, lipids are the main structural component responsible for the membrane's permeability and function. Carbohydrates and nucleic acids are not the primary components of the cell membrane and do not have the same structural role as lipids.
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What is the definition of the term 'momentum' in physics?
- A. Force exerted on an object
- B. Speed of an object in motion
- C. Mass in motion
- D. Distance traveled per unit time
Correct Answer: C
Rationale: Momentum in physics is the product of an object's mass and its velocity. It is a vector quantity that describes the motion of an object and is given by the formula p = mv, where p is momentum, m is mass, and v is velocity. Therefore, momentum is best described as the mass of an object in motion. Choice A, 'Force exerted on an object,' is incorrect because force is not equivalent to momentum. Choice B, 'Speed of an object in motion,' is incorrect because speed only considers the rate of motion and not the mass aspect. Choice D, 'Distance traveled per unit time,' is incorrect as it relates to speed and not momentum, which involves both mass and velocity.
What is the process by which a solid changes directly into a liquid?
- A. Melting
- B. Condensation
- C. Sublimation
- D. Deposition
Correct Answer: A
Rationale: The correct answer is A: Melting. Melting is the process through which a solid substance changes directly into a liquid. Choice B, Condensation, is the transition from gas to liquid. Choice C, Sublimation, refers to the direct change from solid to gas. Choice D, Deposition, is the direct transition from gas to solid, not from solid to liquid as in the question.
Which of the following joints allows for side-to-side bending movements?
- A. Hinge joint
- B. Ball-and-socket joint
- C. Gliding joint
- D. Saddle joint
Correct Answer: C
Rationale: The correct answer is C, Gliding joint. Gliding joints allow for side-to-side bending movements. These joints are found between the small bones of the wrist and ankle, allowing for flexibility and movement in multiple directions. Hinge joints (A) enable movement in one plane, akin to a door hinge. Ball-and-socket joints (B) allow for a wide range of motion across multiple directions. Saddle joints (D) facilitate movement in two planes.
What is the unit of measurement for momentum?
- A. Newton-second (N·s)
- B. Kilogram-meter (kg·m)
- C. Joule (J)
- D. Meter per second (m/s)
Correct Answer: A
Rationale: The correct unit of measurement for momentum is Newton-second (N·s). Momentum is calculated as the product of an object's mass and its velocity. The unit of mass is kilograms (kg) and the unit of velocity is meters per second (m/s). Therefore, the unit of momentum is kilogram-meter per second (kg·m/s). By Newton's second law of motion (F = ma), force is measured in Newtons (N), which is equivalent to kg·m/s². Multiplying the unit of force (N) by the unit of time (s) gives the unit of momentum as Newton-second (N·s). Choice B, Kilogram-meter (kg·m), is incorrect because it represents the unit of work or energy, not momentum. Choice C, Joule (J), is incorrect as it is a unit of energy. Choice D, Meter per second (m/s), is incorrect as it represents velocity alone, not momentum which is a vector quantity involving mass and velocity.
What is the longest bone in the human body?
- A. Tibia
- B. Fibula
- C. Femur
- D. Humerus
Correct Answer: C
Rationale: The femur is indeed the longest bone in the human body. It extends from the hip to the knee, providing crucial support for the body's weight and enabling various movements. The tibia and fibula are bones in the lower leg, while the humerus is located in the upper arm. Therefore, choices A, B, and D are incorrect in this context.