Nokea
What is the building block of RNA?
- A. Amino acid
- B. Nucleotide
- C. Protein
- D. Fatty acid
Correct Answer: B
Rationale: Nucleotide: Nucleotides are the building blocks of RNA. A nucleotide consists of a nitrogenous base (adenine, guanine, cytosine, or uracil in RNA), a sugar (ribose in RNA), and a phosphate group. A) Amino acid: Amino acids are the building blocks of proteins, not RNA. C) Protein: Proteins are made up of amino acids, not nucleotides. D) Fatty acid: Fatty acids are components of lipids, not RNA.
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A ball is rolling across the floor and comes to a stop on its own. What force caused the ball to stop?
- A. Gravitational force
- B. Normal force from the floor
- C. Air resistance
- D. None of the above
Correct Answer: C
Rationale: The force that caused the ball to stop rolling across the floor is air resistance. As the ball moves through the air, air resistance acts in the opposite direction of its motion, gradually slowing it down until it comes to a stop. In this scenario, the ball is not in contact with the floor, so the normal force from the floor does not play a role in stopping the ball. Gravitational force acts to pull objects towards the center of the Earth and would not directly stop the ball in this situation. Therefore, air resistance is the force that opposes the motion of the rolling ball and causes it to come to a stop.
What are Merkel cells, located in the epidermis, specialized for?
- A. Melanin production
- B. Temperature sensation
- C. Touch perception
- D. Immune defense
Correct Answer: C
Rationale: Merkel cells are specialized touch receptors located in the epidermis of the skin. Their primary function is to perceive light touch and pressure. They play a crucial role in the sensory perception of touch stimuli. Option A, melanin production, is incorrect because Merkel cells are not involved in producing melanin. Option B, temperature sensation, is incorrect as Merkel cells are not specialized for sensing temperature. Option D, immune defense, is also incorrect as Merkel cells do not have a role in immune defense mechanisms.
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.
How does kinetic energy change when the velocity of an object is doubled?
- A. Kinetic energy is halved
- B. Kinetic energy quadruples
- C. Kinetic energy doubles
- D. Kinetic energy remains the same
Correct Answer: B
Rationale: Kinetic energy is directly proportional to the square of the velocity of an object according to the kinetic energy formula (KE = 0.5 * m * v^2). When the velocity is doubled, the kinetic energy increases by a factor of 2^2 = 4. Therefore, the kinetic energy quadruples when the velocity of an object is doubled. Choice A is incorrect because halving the kinetic energy would be the result if the velocity was halved, not doubled. Choice C is incorrect because doubling the velocity would result in a fourfold increase in kinetic energy, not just a double. Choice D is incorrect because kinetic energy is directly related to the velocity of an object, so if the velocity changes, the kinetic energy changes accordingly.
What is the term for a solution that has a lower concentration of solute compared to another solution?
- A. Saturated solution
- B. Unsaturated solution
- C. Dilute solution
- D. Concentrated solution
Correct Answer: B
Rationale: An unsaturated solution is the term used for a solution that has a lower concentration of solute compared to another solution. In an unsaturated solution, more solute could still be dissolved. The other options are incorrect. A saturated solution (A) contains the maximum amount of solute that can be dissolved and is in equilibrium with undissolved solute. A dilute solution (C) has a low concentration of solute, but it does not imply a comparison to another solution. A concentrated solution (D) has a high concentration of solute compared to the solvent, which is opposite to what is described in the question.