Nursing Elites

1. Which cells myelinate neurons in the CNS?

• A. Schwann cells
• B. Astrocytes
• C. Microglia
• D. Oligodendrocytes

Correct answer: D

Rationale: The correct answer is D, Oligodendrocytes. Oligodendrocytes are responsible for myelinating neurons in the central nervous system (CNS). Schwann cells, found in the peripheral nervous system, are responsible for myelinating neurons there. Astrocytes support and maintain the neuronal environment, while microglia function as immune cells in the CNS, participating in immune responses and cellular debris clearance. Therefore, choices A, B, and C are incorrect for myelination of CNS neurons.

2. Which type of glial cell provides structural support and insulation for neurons in the central nervous system?

• A. Schwann cells
• B. Astrocytes
• C. Oligodendrocytes
• D. Microglia

Correct answer: C

Rationale: Oligodendrocytes are a type of glial cell that provides structural support and insulation for neurons in the central nervous system by forming myelin sheaths around axons. Schwann cells (option A) perform a similar function but in the peripheral nervous system. Astrocytes (option B) are involved in providing nutrients to neurons, maintaining the chemical environment, and repairing damage. Microglia (option D) are primarily responsible for immune defense in the central nervous system, not for providing structural support and insulation for neurons.

3. What is the correct way to represent 8,600,000,000,000 in scientific notation with two significant figures?

• A. 8.6 x 10^12
• B. 8.6 x 10^-12
• C. 8.6 x 10^11
• D. 8.60 x 10^12

Correct answer: A

Rationale: The correct way to represent 8,600,000,000,000 in scientific notation with two significant figures is 8.6 x 10^12. Scientific notation involves expressing a number as a decimal (with one non-zero digit before the decimal point) multiplied by a power of 10. In this case, 8,600,000,000,000 is correctly written as 8.6 x 10^12 to maintain two significant figures and the appropriate magnitude. Choice B (8.6 x 10^-12) is incorrect as it represents a very small number due to the negative exponent. Choice C (8.6 x 10^11) is incorrect as it does not account for the magnitude of the original number. Choice D (8.60 x 10^12) is incorrect because it unnecessarily adds a zero after the decimal point, which is not warranted by the original number's precision.

4. Which of the following is used to record the measurable electrical activity of the brain?

• A. CAT scan
• B. MRI scan
• C. Electroencephalogram (EEG)
• D. X-ray

Correct answer: C

Rationale: The correct answer is an Electroencephalogram (EEG). An EEG is specifically designed to record the measurable electrical activity of the brain. It does so by using small, flat metal discs (electrodes) attached to the scalp to detect brain activity. This test is crucial in diagnosing various conditions like seizures, epilepsy, head injuries, dizziness, headaches, and brain tumors. The other options, CAT scan, MRI scan, and X-ray, are imaging techniques that do not directly measure the brain's electrical activity. CAT scan and MRI scan provide detailed images of the brain's structure, while X-ray is more suited for visualizing bone structures or dense tissues.

5. Two mice are both heterozygous for two traits: white fur (Ww) and short fur (Ss). Their offspring are most likely to have which of the following genotypes for these traits?

• A. wwss
• B. WWSS
• C. WwSs
• D. WWSs

Correct answer: C

Rationale: When two mice that are heterozygous for white fur (Ww) and short fur (Ss) mate, they can produce offspring with different combinations of the two traits. The Punnett square for this cross shows that the most likely genotype for the offspring is WwSs. In this case, each offspring receives one allele for white fur (W) and one for short fur (S) from each parent, resulting in a heterozygous genotype for both traits. Choice A (wwss) is incorrect as it represents a homozygous recessive genotype for both traits. Choice B (WWSS) is also incorrect as it represents a homozygous dominant genotype for both traits. Choice D (WWSs) is incorrect as it represents a genotype where one trait is homozygous dominant (W) and the other is heterozygous (S), which is not the most likely outcome based on the given parental genotypes.

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