Nursing Elites

1. What effect does a catalyst have on a chemical reaction?

• A. It speeds up the reaction.
• B. It slows down the reaction.
• C. It makes a reaction go in reverse.
• D. It prevents a reaction from taking place.

Correct answer: A

Rationale: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It works by providing an alternate pathway for the reaction to occur, lowering the activation energy needed for the reaction to proceed. As a result, more reactant molecules can overcome this energy barrier and participate in the reaction, leading to a faster overall reaction rate. This explanation contradicts choices B, C, and D as a catalyst does not slow down, reverse, or prevent a reaction; instead, it accelerates the reaction by facilitating a more efficient route for the reaction to take place. Therefore, the correct answer is that a catalyst speeds up the reaction.

2. What is the process by which a large, unstable nucleus splits into two smaller nuclei, releasing neutrons and energy?

• A. Alpha decay
• B. Beta decay
• C. Gamma decay
• D. Nuclear fission

Correct answer: D

Rationale: Nuclear fission is the correct answer. It is the process in which a large, unstable nucleus splits into two smaller nuclei, releasing neutrons and energy. Alpha decay, beta decay, and gamma decay involve the emission of alpha particles, beta particles, and gamma rays, respectively. These decay processes do not result in the splitting of a nucleus like nuclear fission does.

3. What is the primary function of the atrioventricular (AV) node within the heart?

• A. Generate the electrical impulse for contraction (pacemaker function)
• B. Transmit the electrical impulse from the atria to the ventricles, regulating the timing of contraction.
• C. Increase blood pressure within the ventricles during systole.
• D. Separate oxygenated and deoxygenated blood flow in the heart.

Correct answer: B

Rationale: The correct answer is B: Transmit the electrical impulse from the atria to the ventricles, regulating the timing of contraction. The primary function of the atrioventricular (AV) node is to coordinate the transmission of electrical signals between the atria and the ventricles. It ensures proper timing between atrial and ventricular contractions, allowing for efficient blood pumping through the heart. Choice A is incorrect because the AV node does not generate the initial electrical impulse; that role is typically attributed to the sinoatrial (SA) node. Choice C is incorrect as the AV node does not directly influence blood pressure within the ventricles. Choice D is also incorrect as the separation of oxygenated and deoxygenated blood is primarily achieved by the anatomical structure of the heart (e.g., atria and ventricles) and not the AV node.

4. A ball is thrown upwards. Which of the following statements is TRUE about its potential energy and kinetic energy at the peak of its trajectory?

• A. Both potential and kinetic energy are zero.
• B. Potential energy is maximum and kinetic energy is minimum.
• C. Potential energy is minimum and kinetic energy is maximum.
• D. Both potential and kinetic energy remain constant.

Correct answer: B

Rationale: At the peak of its trajectory, the ball momentarily stops moving before falling back down. This means its kinetic energy is at a minimum because it has come to a stop. At the same time, its potential energy is at a maximum because it is at the highest point in its trajectory, where it has the most potential to fall and convert that potential energy into kinetic energy as it descends. Choice A is incorrect because at the peak, the ball still has potential energy due to its height. Choice C is incorrect because kinetic energy is at a minimum when the ball is momentarily at rest. Choice D is incorrect because the energy conversion between potential and kinetic energy occurs at different points in the trajectory.

5. What is the difference between polygenic inheritance and pleiotropy?

• A. Polygenic inheritance involves multiple genes influencing one trait, while pleiotropy involves one gene affecting multiple traits.
• B. Polygenic inheritance is found in simple Mendelian traits, while pleiotropy is found in complex traits.
• C. Polygenic inheritance is always quantitative, while pleiotropy can be qualitative or quantitative.
• D. Both involve multiple genes and multiple traits, but the specific mechanisms differ

Correct answer: A

Rationale: - Polygenic inheritance refers to the situation where a trait is influenced by multiple genes, each contributing a small effect to the phenotype. These traits often show continuous variation and are not easily categorized into discrete categories. - Pleiotropy, on the other hand, occurs when a single gene influences multiple, seemingly unrelated traits. This means that a mutation in one gene can lead to multiple phenotypic effects across different traits or characteristics. - Therefore, the key difference between polygenic inheritance and pleiotropy lies in the number of genes involved in influencing a trait (multiple genes in polygenic inheritance vs. one gene in pleiotropy) and the direction of influence (one trait affected by multiple genes in polygenic inheritance vs. multiple traits affected by one gene in pleiotropy).

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