Nursing Elites

1. How do killer T cells recognize infected cells?

• A. The B cells flag the infected cells with amino acids.
• B. Tiny bits of the virus's RNA are left around the cell.
• C. Macrophages show up to help consume the infected cell.
• D. The T cells have receptors that recognize the proteins the virus leaves on the surface of the cell.

Correct answer: D

Rationale: Killer T cells recognize infected cells by detecting viral proteins displayed on the surface of these cells. The T cells possess receptors specifically designed to identify these viral proteins, allowing them to target and eliminate the infected cells. Choice A is incorrect because B cells are not directly involved in the recognition process of infected cells by killer T cells. Choice B is incorrect because tiny bits of the virus's RNA being left around the cell is not how killer T cells primarily recognize infected cells. Choice C is incorrect because while macrophages play a role in immune responses, they do not directly assist in the recognition of infected cells by killer T cells.

2. Which of the following is the control group in the above experiment?

• A. tank A
• B. tank B
• C. tank C
• D. There is no control group in this experiment.

Correct answer: D

Rationale: The correct answer is D: There is no control group in this experiment. A control group is a group in an experiment that does not receive the treatment being studied in order to serve as a baseline for comparison. In this case, all three tanks (A, B, and C) are being treated with different amounts of fertilizer, and there is no group that is left untreated to serve as a control for comparison. Choices A, B, and C are incorrect because they all represent tanks that are part of the experimental groups receiving different amounts of fertilizer, thus none of them can be considered the control group.

3. Which of the following describes the flow of genetic information from DNA to protein?

• A. Replication
• B. Transcription
• C. Translation
• D. Both transcription and translation

Correct answer: D

Rationale: The correct answer is D, 'Both transcription and translation.' Genetic information flows from DNA to RNA through transcription and from RNA to protein through translation. Replication is the process of copying DNA to produce an identical DNA molecule. Choice A, 'Replication,' is incorrect because replication is not directly involved in the flow of genetic information from DNA to protein. Choice B, 'Transcription,' is incorrect as it represents the process of synthesizing RNA from a DNA template, which is the initial step in the flow of genetic information. Choice C, 'Translation,' is also incorrect as it refers to the process of translating the information in mRNA into a sequence of amino acids during protein synthesis, which is the second step in the flow of genetic information.

4. What are the four main types of macromolecules that are essential for life?

• A. Carbohydrates, lipids, proteins, and nucleic acids
• B. Carbohydrates, proteins, fats, and vitamins
• C. Minerals, vitamins, proteins, and fats
• D. Carbohydrates, lipids, proteins, and hormones

Correct answer: A

Rationale: The correct answer is A: Carbohydrates, lipids, proteins, and nucleic acids. These four types of macromolecules are essential for life as they serve crucial roles in various cellular processes. Carbohydrates are the primary energy source for cells and provide structural support. Lipids function as energy storage molecules and are essential components of cell membranes. Proteins have diverse functions in cellular processes, acting as enzymes, structural components, and more. Nucleic acids, like DNA and RNA, carry genetic information and are crucial for protein synthesis. Choices B, C, and D are incorrect because they include elements like fats, vitamins, minerals, and hormones, which are not the main types of macromolecules essential for life.

5. A light ray travels from air (refractive index 1.00) into water (refractive index 1.33). What happens to its speed and direction?

• A. Speed increases, direction bends towards the normal.
• B. Speed increases, direction bends away from the normal.
• C. Speed decreases, direction bends towards the normal.
• D. Speed and direction remain unchanged.

Correct answer: C

Rationale: When a light ray travels from air (lower refractive index) to water (higher refractive index), its speed decreases due to the change in the medium. This is because light travels slower in denser mediums. As the light ray enters the denser medium, water in this case, it bends towards the normal (the line perpendicular to the surface of the water). This phenomenon is known as refraction. Choice A is incorrect as the speed of light decreases when entering a denser medium. Choice B is incorrect as the direction bends towards the normal, not away from it. Choice D is incorrect as the speed and direction of the light ray do change when moving from air to water.

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