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Which neurotransmitter is associated with pleasure, reward, and motivation, and is often implicated in conditions such as addiction?
- A. Acetylcholine
- B. Dopamine
- C. Serotonin
- D. GABA (Gamma-aminobutyric acid)
Correct Answer: B
Rationale: Dopamine is the neurotransmitter associated with pleasure, reward, and motivation. It plays a crucial role in the brain's reward system and is often implicated in conditions such as addiction. Acetylcholine is involved in muscle movement and memory, serotonin is linked to mood regulation, and GABA is an inhibitory neurotransmitter that helps reduce neuronal excitability. Therefore, the correct answer is dopamine as it aligns with the neurotransmitter functions related to pleasure, reward, and motivation, distinct from the roles of acetylcholine, serotonin, and GABA.
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Which phenomenon describes the separation of light into its component colors when passing through a prism?
- A. Refraction
- B. Diffraction
- C. Dispersion
- D. Reflection
Correct Answer: C
Rationale: Dispersion is the phenomenon that describes the separation of light into its component colors when passing through a prism. When white light enters a prism, it is refracted at different angles depending on its wavelength, causing the colors to spread out. Refraction is the bending of light as it passes from one medium to another, not the separation of colors. Diffraction is the bending of light around obstacles, not the separation of colors. Reflection is the bouncing back of light rays from a surface, not the separation of colors. In the context of a prism, dispersion plays a key role in the creation of a spectrum of colors by separating the different wavelengths present in white light.
What is the common name for the organic compound CH₃OH?
- A. Methane
- B. Ethanol
- C. Methanol
- D. Butanol
Correct Answer: C
Rationale: The common name for the organic compound CH₃OH is methanol. Methane (A) has the chemical formula CH₄. Ethanol (B) corresponds to the formula C₂H₅OH. Butanol (D) is a compound with the formula C₄H₉OH. The correct answer is C - Methanol, which is the common name for CH₃OH, while the other options correspond to different organic compounds with distinct formulas. Therefore, methanol is the correct choice when identifying the common name for the compound CH₃OH.
What is the name of the strong acid produced by the stomach to help break down food?
- A. Hydrochloric acid
- B. Lactic acid
- C. Bile
- D. Fatty acid
Correct Answer: A
Rationale: The correct answer is A, hydrochloric acid. The stomach produces hydrochloric acid to aid in the digestion process by breaking down food, particularly proteins. This acid is crucial for the proper absorption of nutrients in the stomach. Lactic acid is produced in muscles during intense exercise, not in the stomach. Bile is produced by the liver to assist in digestion, primarily in the small intestine, not in the stomach. Fatty acids are molecules found in fats with different functions in the body, but they are not the primary acid produced by the stomach for digestion.
Which hormones are responsible for stimulating the development of sex organs and secondary sex characteristics during puberty?
- A. Growth hormone
- B. Testosterone (in males) and Estrogen (in females)
- C. Insulin
- D. Thyroid hormone
Correct Answer: B
Rationale: Testosterone and estrogen are the primary sex hormones responsible for the development of male and female sex organs, respectively, and the emergence of secondary sex characteristics during puberty. Growth hormone, insulin, and thyroid hormone do not directly influence the development of sex organs and secondary sex characteristics during puberty. Growth hormone primarily regulates growth and metabolism, insulin regulates blood sugar levels, and thyroid hormone controls metabolism and energy levels. Therefore, choices A, C, and D are incorrect for this question.
What structures provide comprehensive protection for the brain?
- A. Skull
- B. Meninges (Membranes)
- C. Cerebrospinal fluid
- D. All of the above
Correct Answer: D
Rationale: The brain is a vital organ that requires robust protection, which is provided by a combination of structures. The skull acts as a hard, protective covering for the brain, shielding it from external trauma and injury. The meninges encompass three layers of membranes (dura mater, arachnoid mater, and pia mater) that envelop the brain and spinal cord, offering additional protection and cushioning. Cerebrospinal fluid, a clear, colorless fluid surrounding the brain and spinal cord, acts as a shock absorber and provides nutrients to the central nervous system. The combined function of the skull, meninges, and cerebrospinal fluid ensures comprehensive protection for the brain, making option D, 'All of the above,' the correct answer. Choices A, B, and C are not individually sufficient to provide comprehensive protection, but together, they form a multi-layered defense system for the brain.