Nursing Elites

1. Most catalysts found in biological systems are which of the following?

• A. Special lipids called cofactors.
• B. Special proteins called enzymes.
• C. Special lipids called enzymes.
• D. Special proteins called cofactors.

Correct answer: B

Rationale: Enzymes are special proteins that act as catalysts in biological systems. They accelerate chemical reactions by lowering the activation energy required for the reaction to occur. Enzymes play a critical role in the regulation of metabolic pathways and are essential for various biological processes. While some enzymes may require cofactors for activity, the enzymes themselves are the catalysts in biological systems. Therefore, choice B, special proteins called enzymes, is the most suitable answer. Choices A, C, and D are incorrect because enzymes, not lipids, are the primary catalysts in biological systems.

2. Which of the following organs does not belong with the others?

• A. Thyroid gland
• B. Stomach
• C. Intestines
• D. Pancreas

Correct answer: B

Rationale: The correct answer is B - Stomach. The stomach is primarily involved in the digestive system, breaking down food through digestion. In contrast, the thyroid gland, intestines, and pancreas are part of the endocrine system or digestive system, involved in hormone production, nutrient absorption, and digestion. Therefore, the stomach stands out as the odd one in this group as it is the only organ specifically dedicated to digestion, while the others have dual roles or different primary functions.

3. How can a single gene mutation lead to multiple phenotypes depending on the organism?

• A. Pleiotropy describes the effect of one gene influencing multiple seemingly unrelated traits.
• B. Epigenetics involves environmental factors modifying gene expression without altering the DNA sequence.
• C. Genetic drift refers to random changes in allele frequencies within a population.
• D. Gene regulation controls the timing and level of gene expression within an organism.

Correct answer: A

Rationale: A single gene mutation can lead to multiple phenotypes through pleiotropy, where one gene influences diverse traits or functions in an organism. This phenomenon occurs when the mutated gene affects different biochemical pathways, developmental processes, or cellular functions, resulting in a cascade of downstream effects that manifest as a variety of phenotypic outcomes. Choice B, epigenetics, involves modifications in gene expression influenced by environmental factors without altering the DNA sequence, which is not directly related to the question about single gene mutations causing multiple phenotypes. Choice C, genetic drift, refers to random changes in allele frequencies within a population, which is unrelated to the impact of a single gene mutation on multiple phenotypes. Choice D, gene regulation, focuses on controlling the timing and level of gene expression within an organism, which is not directly addressing how a single gene mutation can lead to diverse phenotypes.

4. What is the term for the pressure exerted by blood against the walls of blood vessels?

• A. Heart rate
• B. Blood pressure
• C. Cardiac output
• D. Stroke volume

Correct answer: B

Rationale: Blood pressure is the term for the pressure exerted by blood against the walls of blood vessels. It is measured in millimeters of mercury (mmHg) and consists of two numbers: systolic pressure (the top number) and diastolic pressure (the bottom number). Heart rate (A) is the number of times the heart beats per minute, cardiac output (C) is the volume of blood pumped by the heart per minute, and stroke volume (D) is the volume of blood pumped by the heart in one contraction. Understanding blood pressure is crucial in assessing cardiovascular health and the risk of various conditions like hypertension.

5. Which of the following neurotransmitters slows down the activity of neurons to prevent overexcitation?

• A. Acetylcholine
• B. Dopamine
• C. GABA
• D. Serotonin

Correct answer: C

Rationale: The correct answer is C: GABA (gamma-aminobutyric acid). GABA is an inhibitory neurotransmitter that slows down neuronal activity, helping to prevent overexcitation in the brain. It counterbalances the effects of excitatory neurotransmitters like glutamate, playing a crucial role in maintaining the balance of neuronal activity in the brain. Acetylcholine (Choice A) is primarily an excitatory neurotransmitter involved in muscle movement and cognitive functions. Dopamine (Choice B) plays a role in reward-motivated behavior and motor control. Serotonin (Choice D) is involved in regulating mood, appetite, and sleep but is not primarily responsible for slowing down neuronal activity to prevent overexcitation.

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