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. According to the Cahn-Ingold-Prelog (CIP) ranking system, which functional group has the highest priority?

• A. Alcohol (OH)
• B. Aldehyde (CHO)
• C. Carboxylic Acid (COOH)
• D. Amine (NH2)

Correct answer: C

Rationale: In the Cahn-Ingold-Prelog (CIP) ranking system, functional groups are prioritized based on the atomic number of the atoms directly attached to the functional group. Carboxylic acid (COOH) holds the highest priority as the carbon atom is directly bonded to two oxygen atoms, which have higher atomic numbers compared to carbon, hydrogen, or nitrogen. The higher the atomic number of the attached atoms, the higher the priority of the functional group in the CIP ranking system. Therefore, choices A, B, and D are incorrect as they have lower atomic numbers in the atoms directly attached to them, making them lower in priority according to the CIP system.

3. What is the process of transporting molecules across the cell membrane against a concentration gradient called?

• A. Diffusion
• B. Osmosis
• C. Active transport
• D. Facilitated diffusion

Correct answer: C

Rationale: A) Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration, which does not require energy input. B) Osmosis is the movement of water molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. C) Active transport is the process of transporting molecules across the cell membrane against a concentration gradient, requiring energy in the form of ATP to move substances from an area of lower concentration to an area of higher concentration. D) Facilitated diffusion is a type of passive transport that involves the use of transport proteins to move molecules across the cell membrane from an area of higher concentration to an area of lower concentration, without the need for energy input.

4. Which of the following statements regarding heart valves is correct?

• A. The atrioventricular valves lie between the atria and the ventricles.
• B. The pulmonary semilunar valve lies between the right ventricle and the pulmonary trunk.
• C. The atrioventricular valves prevent backflow into the atria when the ventricles contract.
• D. All of the above

Correct answer: D

Rationale: All of the statements are correct regarding heart valves. Choice A is accurate as the atrioventricular valves indeed lie between the atria and the ventricles. Choice B correctly identifies the location of the pulmonary semilunar valve. Choice C is true as the atrioventricular valves do prevent backflow into the atria during ventricular contraction. Therefore, selecting 'All of the above' as the correct answer is appropriate as all statements are accurate.

5. What macromolecules are formed from amino acids, and what are their roles?

• A. Lipids; store energy
• B. Carbohydrates; provide energy
• C. Proteins; perform various functions like catalysis, transport, and structural support
• D. Nucleic acids; store genetic information

Correct answer: C

Rationale: The correct answer is C. Proteins are macromolecules formed from amino acids and have diverse roles, such as serving as enzymes, transport molecules, and providing structural support. They are essential for catalysis, cellular communication, immune response, and many other functions in living organisms. Choices A, B, and D are incorrect. Lipids are not formed from amino acids but from fatty acids and glycerol, mainly serving as energy storage molecules. Carbohydrates are composed of sugars and provide energy to the body. Nucleic acids, like DNA and RNA, are made up of nucleotides and store genetic information in cells.

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