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. An atom has 17 protons, 20 neutrons, and 17 electrons. What is its mass, in amu?

• A. 17
• B. 20
• C. 37
• D. 54

Correct answer: C

Rationale: The atomic mass of an atom is the sum of the protons and neutrons in its nucleus. In this case, the atom has 17 protons and 20 neutrons, totaling 37 particles in the nucleus. Electrons are not considered in the atomic mass calculation as their mass is negligible compared to protons and neutrons. Therefore, the mass of the atom in atomic mass units (amu) is 37.

3. In the context of optical fibers, chromatic dispersion refers to:

• A. The total internal reflection of light
• B. The spreading of light pulses due to different colors traveling at slightly different speeds
• C. The bending of light at the fiber core-cladding interface
• D. The absorption of light by the fiber material

Correct answer: B

Rationale: Chromatic dispersion in optical fibers refers to the spreading of light pulses due to different colors (wavelengths) traveling at slightly different speeds. This phenomenon can cause the different components of a light pulse to arrive at the receiver at slightly different times, leading to signal distortion. Choice A is incorrect because total internal reflection refers to the phenomenon where light is reflected back into the medium it originated from when hitting the boundary at an angle greater than the critical angle. Choice C is incorrect as it describes the principle of light being guided within an optical fiber through total internal reflection at the core-cladding interface. Choice D is incorrect as the absorption of light by the fiber material does not relate to chromatic dispersion.

4. Which of the following statements is correct based on anatomical terms?

• A. The shoulder joint is proximal to the neck.
• B. The elbow joint is superior to the shoulder.
• C. The thoracic vertebrae are superior to the cervical vertebrae.
• D. The thumb is on the lateral aspect of the hand.

Correct answer: D

Rationale: Option D is the correct answer based on anatomical terms. The thumb is indeed located on the lateral aspect of the hand, following anatomical positioning. The terms 'proximal,' 'superior,' and 'inferior' are used in relation to the center of the body or a specific point of reference, while 'lateral' and 'medial' describe positions further away or closer to the midline of the body. Therefore, the thumb being on the lateral side of the hand is an accurate anatomical description. Choices A, B, and C are incorrect because they do not align with anatomical terminology. In anatomical terms, 'proximal' refers to a position closer to the center of the body, 'superior' indicates a position above or higher than another part, and 'inferior' signifies a position below or lower than another part. The shoulder joint is distal to the neck, the elbow is inferior to the shoulder, and the cervical vertebrae are superior to the thoracic vertebrae.

5. What type of bond connects amino acids to form proteins?

• A. Covalent
• B. Peptide
• C. Ionic
• D. Hydrogen

Correct answer: B

Rationale: The correct answer is 'Peptide'. Peptide bonds are the specific type of bond that connects amino acids together to form proteins. These bonds form through a condensation reaction between the amino group of one amino acid and the carboxyl group of another amino acid, creating a covalent bond. While covalent bonds are involved in the formation of peptide bonds, the direct bond connecting amino acids in proteins is the peptide bond. Ionic bonds involve the attraction between charged particles, and hydrogen bonds are weaker bonds compared to covalent and peptide bonds, playing a different role in protein structure.

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