how do the killer t cells recognize infected cells

ATI TEAS 7

ATI TEAS Practice Science Test

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. How do DNA and RNA function together as part of the human genome?

A. DNA carries genetic information from RNA to the cell cytoplasm.
B. RNA carries genetic information from DNA to the cell cytoplasm.
C. DNA and RNA carry genetic information from the cell nucleus to the cytoplasm.
D. DNA and RNA do not interact within the cell.

Correct answer: B

Rationale: The correct answer is B. RNA acts as a messenger carrying genetic instructions from the DNA in the nucleus to the cytoplasm, where proteins are synthesized. This process is known as transcription and translation, where DNA provides the blueprint for protein synthesis, and RNA delivers this information to the cellular machinery in the cytoplasm. Choice A is incorrect as it inaccurately states that DNA carries genetic information from RNA, which is the opposite of the actual flow of information. Choice C is incorrect as it suggests that both DNA and RNA together carry genetic information from the nucleus to the cytoplasm, which is not accurate. Choice D is incorrect as DNA and RNA do interact within the cell, playing crucial roles in genetic information processing and protein synthesis.

3. Which of the following is NOT a characteristic of living organisms?

A. Made up of cells
B. Able to reproduce
C. Require energy
D. Non-motile

Correct answer: D

Rationale: A) Made up of cells: All living organisms are composed of one or more cells, a fundamental characteristic of life as defined by cell theory. B) Able to reproduce: Reproduction is a key characteristic of living organisms to pass on genetic information. C) Require energy: Energy is essential for carrying out life processes like growth and maintenance of homeostasis. D) Non-motile: While some living organisms are non-motile, movement is common in many organisms for survival activities like finding food, escaping predators, and responding to the environment. Therefore, being non-motile is not a universal characteristic of living organisms, making it the correct answer in this context.

4. What is the main function of white blood cells?

A. Transport oxygen
B. Fight infection
C. Produce antibodies
D. Regulate body temperature

Correct answer: B

Rationale: The main function of white blood cells is to fight infection, making choice B the correct answer. White blood cells are a crucial component of the immune system, working to defend the body against pathogens and foreign invaders. Choices A, C, and D are incorrect because white blood cells do not primarily transport oxygen, produce antibodies, or regulate body temperature. While some blood cells are involved in these functions, the primary role of white blood cells is to combat infections and maintain the body's immune response.

5. Which valve prevents backflow into the atrium when the ventricles contract?

A. Pulmonary valve
B. Tricuspid valve
C. Mitral valve
D. Aortic valve

Correct answer: B

Rationale: The tricuspid valve (right atrioventricular valve) prevents backflow into the right atrium when the right ventricle contracts. This valve ensures that blood flows in the correct direction, preventing regurgitation into the atrium. The pulmonary valve is responsible for preventing backflow into the right ventricle from the pulmonary artery. The mitral valve prevents backflow into the left atrium, and the aortic valve prevents backflow into the left ventricle from the aorta. Therefore, the correct answer is the tricuspid valve as it specifically addresses the scenario of backflow into the atrium during ventricular contraction.