Nursing Elites

1. Where does most of the chemical digestion take place?

• A. Large intestine
• B. Stomach
• C. Small intestine
• D. Esophagus

Correct answer: C

Rationale: Most of the chemical digestion occurs in the small intestine. Enzymes in the small intestine break down nutrients into smaller molecules that can be absorbed by the body. The stomach plays a role in digestion by breaking down food mechanically and initiating some chemical digestion, but the majority of nutrient breakdown and absorption happens in the small intestine. The large intestine mainly absorbs water and salts, with little to no digestion taking place there. The esophagus is a muscular tube that helps move food from the mouth to the stomach and does not participate in digestion.

2. Which of the following is NOT a recognized mode of natural selection?

• A. Directional selection (favoring one extreme trait value on a spectrum)
• B. Disruptive selection (favoring both extreme trait values on a spectrum)
• C. Stabilizing selection (favoring the average trait value on a spectrum)
• D. Sexual selection (selection based on mate choice that influences reproductive success)

Correct answer: D

Rationale: A) Directional selection is a recognized mode of natural selection where one extreme trait value on a spectrum is favored over others, leading to a shift in the average trait value over time. B) Disruptive selection is a recognized mode of natural selection where both extreme trait values on a spectrum are favored over the average trait value, potentially causing the population to split into distinct groups. C) Stabilizing selection is a recognized mode of natural selection favoring the average trait value on a spectrum over extreme values, resulting in reduced genetic diversity. D) Sexual selection differs from traditional natural selection modes as it involves mate choice and competition for mates, not direct selection pressure on traits affecting survival and reproduction in the environment. Sexual selection can drive the evolution of traits enhancing an individual's attractiveness for mating purposes.

3. What generates action potentials, the all-or-nothing electrical signals traveling along neurons?

• A. Glucose
• B. Sodium and potassium ions
• C. Neurotransmitters
• D. Myelin

Correct answer: B

Rationale: Action potentials, the all-or-nothing electrical signals traveling along neurons, are generated by the movement of sodium and potassium ions across the neuronal membrane. This movement creates changes in the membrane potential, leading to the propagation of the electrical signal along the neuron. Glucose is a source of energy for neurons but is not directly involved in generating action potentials. Neurotransmitters are involved in communication between neurons but do not directly generate action potentials. Myelin is a fatty substance that insulates and speeds up the conduction of action potentials but does not generate them.

4. What happens to the gravitational potential energy of an object as it falls freely?

• A. It decreases
• B. It increases
• C. It remains constant
• D. It becomes zero

Correct answer: A

Rationale: The correct answer is A: 'It decreases.' When an object falls freely, its height decreases, resulting in a decrease in gravitational potential energy. The potential energy is converted into kinetic energy as the object accelerates due to gravity. This conversion process continues until the object reaches the ground or its lowest point, where the gravitational potential energy is minimal or zero. Choice B is incorrect because gravitational potential energy decreases, not increases, during free fall. Choice C is incorrect as gravitational potential energy changes due to the change in height. Choice D is incorrect as the gravitational potential energy does not instantly become zero but decreases gradually as the object falls.

5. 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

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