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Which of the following terms refers to the degeneration of nerve tissue?
- A. Potentiation
- B. Demyelination
- C. Reuptake
- D. Neurogenesis
Correct Answer: B
Rationale: Demyelination specifically refers to the degeneration of the myelin sheath that covers nerve fibers. When demyelination occurs, nerve function and communication can be impaired. Potentiation involves the strengthening of synaptic connections, reuptake is the reabsorption process of neurotransmitters by the presynaptic neuron, and neurogenesis is the generation of new neurons. Therefore, the correct term for the degeneration of nerve tissue among the options provided is demyelination.
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Which term describes the ability of a substance to conduct electricity?
- A. Reactivity
- B. Density
- C. Conductivity
- D. Viscosity
Correct Answer: C
Rationale: Conductivity is the correct term used to describe the ability of a substance to conduct electricity. Reactivity is the measure of a substance's tendency to undergo chemical reactions. Density refers to the mass per unit volume of a substance, while viscosity is a measure of a fluid's resistance to flow. In the context of conducting electricity, conductivity is the most appropriate term as it directly relates to the substance's electrical conductive properties.
What is the term for the chemical reaction that involves the loss of electrons?
- A. Reduction
- B. Oxidation
- C. Neutralization
- D. Precipitation
Correct Answer: B
Rationale: Oxidation is the process where a substance loses electrons. In an oxidation reaction, the substance being oxidized loses electrons, which are gained by another substance. Reduction is the opposite process, where a substance gains electrons. Neutralization is a reaction between an acid and a base to form a salt and water. Precipitation is the formation of a solid from a solution. Therefore, in the context of a chemical reaction involving the loss of electrons, the correct term is oxidation (Choice B).
If you compare a 1 M solution of NaCl to a 1 M solution of glucose (C6H12O6) in water, which solution would have the higher boiling point?
- A. The NaCl solution
- B. The glucose solution
- C. They would have the same boiling point
- D. It depends on the temperature
Correct Answer: A
Rationale: 1. Boiling point elevation: When a solute is added to a solvent, it raises the boiling point of the solution compared to the pure solvent. This phenomenon is known as boiling point elevation.
2. Van't Hoff factor: The extent of boiling point elevation depends on the number of particles the solute dissociates into in the solution. NaCl dissociates into two ions (Na+ and Cl-) in water, while glucose does not dissociate into ions. Therefore, NaCl has a higher Van't Hoff factor than glucose.
3. Colligative properties: Boiling point elevation is a colligative property, meaning it depends on the concentration of the solute particles, not the identity of the solute. Since both NaCl and glucose are 1 M solutions, the NaCl solution will have a higher boiling point due to its higher Van't Hoff factor.
4. Conclusion: The NaCl solution
What is the relationship between genetic drift and the founder effect?
- A. Founder effect is a cause of genetic drift within a small population
- B. Genetic drift is a cause of the founder effect in new populations
- C. They are the same phenomenon with different names
- D. They are unrelated concepts.
Correct Answer: A
Rationale: - The founder effect is a specific type of genetic drift that occurs when a small group of individuals establishes a new population, leading to a loss of genetic variation.
- Genetic drift, on the other hand, is a broader concept that refers to random changes in allele frequencies in a population over time due to chance events.
- Therefore, the founder effect is a specific scenario within the broader concept of genetic drift, where the establishment of a new population by a small number of individuals leads to genetic changes in the population.
When sugar is heated, it breaks down into carbon and water vapor. This is an example of a:
- A. Combination reaction
- B. Decomposition reaction
- C. Double displacement reaction
- D. Single displacement reaction
Correct Answer: B
Rationale: The correct answer is B: Decomposition reaction. When sugar is heated, it undergoes a decomposition reaction where it breaks down into simpler substances, carbon, and water vapor. In a decomposition reaction, a single compound breaks down into two or more simpler substances. This process is the opposite of a combination reaction where two or more substances combine to form a new compound. Choice A, Combination reaction, is incorrect because a combination reaction involves the combination of two or more substances to form a new compound, which is the opposite of what happens when sugar breaks down. Choices C and D, Double displacement reaction and Single displacement reaction, are incorrect as they involve different mechanisms where the atoms or ions of the reactants are exchanged, which is not the case in the breakdown of sugar into carbon and water vapor.