Nursing Elites

1. The neutral theory of molecular evolution proposes that:

• A. Most mutations in DNA are selectively neutral and do not affect an organism's fitness.
• B. All mutations are beneficial and contribute to the adaptation of a population.
• C. The rate of evolution is primarily driven by strong directional selection pressures.
• D. Genetic drift plays a negligible role in shaping genetic variation within populations.

Correct answer: A

Rationale: Rationale: A) The neutral theory of molecular evolution, proposed by Motoo Kimura in the 1960s, suggests that the majority of mutations that occur in DNA are selectively neutral, meaning they do not have a significant impact on an organism's fitness. These neutral mutations are not subject to natural selection and are allowed to accumulate in populations over time. This theory helps explain the high levels of genetic variation observed within populations. B) Option B is incorrect because not all mutations are beneficial. Mutations can be neutral, harmful, or beneficial, and the neutral theory specifically focuses on the idea that many mutations are neutral in their effects. C) Option C is incorrect because the neutral theory suggests that evolution is not primarily driven by strong directional selection pressures. Instead, it emphasizes the role of genetic drift and the accumulation of neutral mutations in shaping genetic variation. D) Option D is incorrect because

2. Which of the following Mendelian laws describes how pairs of alleles within genes separate and recombine independently from other genes?

• A. law of segregation
• B. law of dominance
• C. law of independent assortment
• D. law of predictive traits

Correct answer: C

Rationale: The law of independent assortment describes how alleles of different genes segregate independently during gamete formation. This means that different gene pairs are passed on to offspring separately from one another, allowing for various combinations of traits. Gregor Mendel discovered this law, along with the law of segregation and the law of dominance, through his experiments with pea plants. The law of segregation (choice A) refers to how alleles of a gene separate during gamete formation, while the law of dominance (choice B) states that one allele can mask the presence of another in a heterozygous individual. The 'law of predictive traits' (choice D) is not a recognized Mendelian law and does not accurately describe the principles of genetic inheritance.

3. 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.

4. Which nervous system controls the involuntary 'fight-or-flight' response?

• A. Sympathetic nervous system
• B. Parasympathetic nervous system
• C. Enteric nervous system
• D. Sensory nervous system

Correct answer: A

Rationale: The correct answer is the sympathetic nervous system. The sympathetic nervous system is responsible for activating the body's response to stress or danger, leading to the 'fight-or-flight' response. It prepares the body for action by increasing heart rate, dilating pupils, and redirecting blood flow to muscles. Choice B, the parasympathetic nervous system, is responsible for the body's 'rest-and-digest' activities, which are opposite to the 'fight-or-flight' response. Choice C, the enteric nervous system, primarily regulates the gastrointestinal system and is not directly involved in the 'fight-or-flight' response. Choice D, the sensory nervous system, transmits sensory information from the body to the central nervous system and is not responsible for the physiological changes associated with the 'fight-or-flight' response.

5. Which type of blood cell is responsible for carrying oxygen?

• A. White blood cell
• B. Red blood cell
• C. Platelet
• D. Plasma

Correct answer: B

Rationale: The correct answer is B: Red blood cell. Red blood cells, also known as erythrocytes, are responsible for carrying oxygen from the lungs to the body's tissues. They contain hemoglobin, a protein that binds to oxygen and transports it throughout the body. White blood cells (Choice A) are part of the immune system and help fight infections, not involved in carrying oxygen. Platelets (Choice C) are responsible for blood clotting, not oxygen transport. Plasma (Choice D) is the liquid component of blood that carries various substances like nutrients and waste products, but it does not directly carry oxygen.

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