Nokea
What is the unit of measurement for power?
- A. Joule (J)
- B. Newton (N)
- C. Watt (W)
- D. Kilogram-meter (kg·m)
Correct Answer: C
Rationale: Power is the rate at which work is done or energy is transferred. The unit of measurement for power is the watt (W), named after James Watt, the inventor of the steam engine. The watt is defined as one joule per second, where a joule (J) is the unit of energy. Choice A, Joule (J), is incorrect because a joule is a unit of energy, not power. Choice B, Newton (N), is incorrect as a Newton is a unit of force, not power. Choice D, Kilogram-meter (kg·m), is incorrect as it represents a unit of torque, not power. Therefore, the correct answer is C: Watt (W).
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According to the Law of Conservation of Energy, what happens to the total amount of energy in a closed system?
- A. Increases over time.
- B. Decreases over time.
- C. Remains constant.
- D. Depends on the temperature of the system.
Correct Answer: C
Rationale: According to the Law of Conservation of Energy, the total amount of energy in a closed system remains constant. This principle states that energy cannot be created or destroyed within the system but can only be transformed from one form to another. Therefore, the total energy within the system is conserved and does not change over time. Choice A is incorrect because the total energy in a closed system does not increase over time, as it remains constant. Choice B is incorrect as the total energy does not decrease over time within a closed system. Choice D is incorrect as the conservation of energy is not dependent on the temperature of the system, but rather on the transformation and conservation of energy within the system. Understanding this concept is fundamental for understanding the behavior of energy in various physical systems and processes.
What is the difference between the atomic number and the mass number of an atom?
- A. The atomic number is the number of protons in the nucleus, while the mass number is the total number of protons and neutrons in the nucleus.
- B. The atomic number is the number of electrons in an atom, while the mass number is the total number of protons and neutrons in the nucleus.
- C. The atomic number is the number of neutrons in the nucleus, while the mass number is the total number of protons and electrons in an atom.
- D. The atomic number is the number of protons and neutrons in the nucleus, while the mass number is the total number of electrons in an atom.
Correct Answer: A
Rationale: The atomic number of an atom represents the number of protons in its nucleus, which defines the element's identity. On the other hand, the mass number corresponds to the total sum of protons and neutrons in the nucleus. Therefore, the key distinction between the atomic number and the mass number lies in the fact that the atomic number specifically counts the protons, whereas the mass number encompasses both protons and neutrons. Choice B is incorrect because the atomic number is not related to the number of electrons but rather to the number of protons. Choice C is incorrect because the atomic number is not the number of neutrons but the number of protons. Choice D is incorrect because the atomic number does not include neutrons; it is solely the number of protons.
Which of the following pathologies is caused by a virus?
- A. Asthma
- B. Cystic Fibrosis
- C. Epiglottitis
- D. Influenza
Correct Answer: D
Rationale: The correct answer is D, Influenza. Influenza is a viral infection caused by the influenza virus. Asthma and cystic fibrosis are not caused by viruses. Asthma is a chronic respiratory condition related to inflammation and airway constriction, while cystic fibrosis is a genetic disorder affecting the lungs and other organs. Epiglottitis is most commonly caused by bacteria, particularly Haemophilus influenzae type B, rather than a virus.
Which organelle is responsible for controlling the activities of the cell?
- A. Golgi apparatus
- B. Mitochondria
- C. Nucleus
- D. Ribosomes
Correct Answer: C
Rationale: The nucleus is the organelle responsible for controlling the activities of the cell. It contains the cell's genetic material (DNA) and serves as the command center of the cell, regulating gene expression and directing cellular activities. The nucleus plays a crucial role in cell growth, metabolism, and reproduction. While the Golgi apparatus is involved in processing and packaging proteins, the mitochondria are responsible for producing energy in the form of ATP, and ribosomes are involved in protein synthesis, none of these organelles have the primary function of controlling the activities of the cell like the nucleus does. Therefore, the correct answer is the nucleus.
Which of the following neurotransmitters slows down the activity of neurons to prevent overexcitation?
- A. Acetylcholine
- B. Dopamine
- C. GABA
- D. Serotonin
Correct Answer: C
Rationale: The correct answer is C: GABA (gamma-aminobutyric acid). GABA is an inhibitory neurotransmitter that slows down neuronal activity, helping to prevent overexcitation in the brain. It counterbalances the effects of excitatory neurotransmitters like glutamate, playing a crucial role in maintaining the balance of neuronal activity in the brain. Acetylcholine (Choice A) is primarily an excitatory neurotransmitter involved in muscle movement and cognitive functions. Dopamine (Choice B) plays a role in reward-motivated behavior and motor control. Serotonin (Choice D) is involved in regulating mood, appetite, and sleep but is not primarily responsible for slowing down neuronal activity to prevent overexcitation.