Nursing Elites

1. The Gram stain is a differential staining technique used to classify bacteria based on their cell wall composition. Gram-positive bacteria appear

• A. Pink
• B. Blue
• C. Red
• D. Purple

Correct answer: D

Rationale: The Gram stain is a differential staining technique that categorizes bacteria into two groups based on their cell wall composition: Gram-positive and Gram-negative. Gram-positive bacteria have a thick layer of peptidoglycan in their cell walls, which retains the crystal violet stain used in the Gram staining procedure. Consequently, Gram-positive bacteria appear purple under the microscope after staining. On the other hand, Gram-negative bacteria possess a thinner peptidoglycan layer and an outer membrane that can be penetrated by the counterstain safranin, leading them to appear pink or red. Blue is not typically used to describe the color of bacteria in a Gram stain, making it an incorrect choice.

2. Which of the following is an example of a nonpolar solvent?

• A. Water
• B. Ethanol
• C. Acetone
• D. Hydrochloric acid

Correct answer: B

Rationale: - Water (option A) is a polar solvent due to its uneven distribution of charge, with the oxygen atom being partially negative and the hydrogen atoms being partially positive. - Ethanol (option B) is a nonpolar solvent because it has a symmetrical molecular structure that does not result in significant charge separation. - Acetone (option C) is a polar solvent as it contains a carbonyl group that results in a partial negative charge on the oxygen atom. - Hydrochloric acid (option D) is a polar solvent due to the presence of the highly electronegative chlorine atom, which results in a partial negative charge.

3. Which neurotransmitter is responsible for stimulating muscle contraction?

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

Correct answer: B

Rationale: Acetylcholine is the neurotransmitter responsible for stimulating muscle contraction at the neuromuscular junction. When an action potential reaches the end of a motor neuron, acetylcholine is released into the synaptic cleft and binds to receptors on the muscle cell membrane, leading to muscle contraction. Dopamine, serotonin, and norepinephrine are neurotransmitters that have different functions in the nervous system and are not directly involved in stimulating muscle contraction. Dopamine is involved in reward and pleasure pathways, serotonin regulates mood and behavior, and norepinephrine is involved in the 'fight or flight' response.

4. From which of the following germ layers does the nervous system develop?

• A. Ectoderm
• B. Endoderm
• C. Gastroderm
• D. Mesoderm

Correct answer: A

Rationale: The correct answer is A: Ectoderm. The nervous system develops from the ectoderm, which is the outermost of the three germ layers. The ectoderm gives rise to structures such as the skin, hair, nails, and the entire nervous system. Choices B, C, and D are incorrect because the endoderm gives rise to the lining of the gut and associated organs, the gastroderm is not a recognized germ layer, and the mesoderm forms structures like muscles, bones, blood, and the circulatory system, but not the nervous system.

5. An object is moving in a circle at constant speed. Is there a net force acting on it?

• A. Yes, always
• B. No, never
• C. Only if its speed is changing
• D. Only if its direction is changing

Correct answer: D

Rationale: When an object is moving in a circle at a constant speed, there is a net force acting on it. This net force is directed towards the center of the circle and is responsible for continuously changing the direction of the object's velocity, even though the speed remains constant. Therefore, the correct answer is D because the net force is required to change the direction of the object's motion in a circular path. Choices A, B, and C are incorrect because the presence of a net force is necessary to continuously change the object's direction as it moves in a circular path, irrespective of changes in speed.

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