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Which of the following terms refers to a muscle twitch, a single forceful contraction of a muscle fiber?
- A. Tetanus
- B. Tremor
- C. Fasciculation
- D. Rigidity
Correct Answer: C
Rationale: The correct term for a muscle twitch, a single forceful contraction of a muscle fiber, is 'Fasciculation' (choice C). Fasciculation specifically describes this phenomenon. 'Tetanus' (choice A) refers to sustained muscle contraction, 'Tremor' (choice B) indicates a shaky or quivering movement, and 'Rigidity' (choice D) denotes stiffness or inflexibility in muscles. Therefore, choices A, B, and D are incorrect in the context of a single forceful contraction of a muscle fiber.
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What is the term for the process of breaking a large molecule into smaller fragments by applying heat?
- A. Polymerization
- B. Hydrogenation
- C. Isomerization
- D. Pyrolysis
Correct Answer: D
Rationale: Pyrolysis is the correct answer. It is the process of breaking down large molecules into smaller fragments by applying heat in the absence of oxygen. This results in the decomposition of molecules into simpler compounds. Polymerization, the process of synthesizing large molecules from smaller units, is incorrect as it is the opposite process. Hydrogenation involves adding hydrogen atoms to a compound, usually with a catalyst, which is not related to breaking down large molecules. Isomerization refers to rearranging atoms within a molecule to form isomeric compounds with the same molecular formula but different structural arrangements, which is also unrelated to the process described in the question.
What is the Pauli exclusion principle?
- A. The principle that electrons fill orbitals in order of increasing energy.
- B. The principle that electrons cannot occupy the same orbital with the same spin.
- C. The principle that the maximum number of electrons in an orbital is 2n^2, where n is the energy level of the orbital.
- D. The principle that the attractive force between an electron and the nucleus is inversely proportional to the distance between them.
Correct Answer: B
Rationale: The Pauli exclusion principle states that no two electrons in an atom can have the same set of four quantum numbers. This principle leads to the rule that electrons must have opposite spins when occupying the same orbital. Therefore, electrons cannot occupy the same orbital with the same spin, as stated in option B. Option A is incorrect as it refers to the Aufbau principle, which describes the order in which electrons fill orbitals based on increasing energy. Option C is incorrect as it provides the formula for the maximum number of electrons in an orbital based on the energy level, not the Pauli exclusion principle. Option D is incorrect as it describes Coulomb's law, which deals with the electrostatic force between charged particles, not the Pauli exclusion principle.
What is the primary function of the heart?
- A. Filtering blood
- B. Exchanging gases
- C. Pumping blood throughout the body
- D. Producing hormones
Correct Answer: C
Rationale: The main function of the heart is to pump blood throughout the body. The heart acts as a muscular pump that circulates blood, delivering oxygen and nutrients to the body's tissues and removing waste products. Option A is incorrect because blood filtration is a function of the kidneys, not the heart. Option B is incorrect as gas exchange occurs in the lungs, not the heart. Option D is also incorrect as hormone production is mainly carried out by endocrine glands, not the heart.
When baking soda (sodium bicarbonate) reacts with vinegar (acetic acid), what type of reaction occurs?
- A. Combustion
- B. Double displacement
- C. Decomposition
- D. Synthesis
Correct Answer: B
Rationale: When baking soda (sodium bicarbonate) reacts with vinegar (acetic acid), a double displacement reaction occurs. In this reaction, the positive ions in baking soda switch places with the positive ions in vinegar to form water, carbon dioxide, and a salt. Combustion involves a reaction with oxygen to produce heat and light energy. Decomposition is the breakdown of a compound into simpler substances, which is not the case in the given reaction. Synthesis is the combination of substances to form a more complex compound, which is also not the type of reaction observed when baking soda and vinegar react.
Edema, characterized by swelling due to fluid buildup, can be a sign of:
- A. Heart failure
- B. Liver disease
- C. Lymphatic system dysfunction
- D. All of the above
Correct Answer: D
Rationale: Edema is the swelling caused by fluid retention in the body tissues. It can indicate various underlying conditions. Heart failure can lead to fluid buildup due to the heart's ineffective pumping. Liver disease can cause edema by reducing protein production, leading to fluid leakage into tissues. Dysfunction of the lymphatic system can impair fluid drainage, contributing to edema. Therefore, all of the above conditions can manifest with edema, making the correct answer 'All of the above.' Choices A, B, and C are all valid causes of edema, making them incorrect when considered individually. Selecting 'All of the above' encompasses all the possible causes of edema.