Nursing Elites

1. Which of the following correctly identifies a difference between the primary and secondary immune response?

• A. In the secondary response, macrophages migrate to the lymph nodes to present the foreign microorganism to helper T lymphocytes.
• B. The humoral immunity that characterizes the primary response is coordinated by B lymphocytes.
• C. The primary response is quicker and more powerful than the secondary response.
• D. Suppressor T cells are activated in the secondary response to prevent an overactive immune response.

Correct answer: C

Rationale: The correct answer is C. The primary immune response is slower and less powerful compared to the secondary immune response. During the primary response, immune cells encounter the antigen for the first time, necessitating the activation and proliferation of specific immune cells. In contrast, the secondary response benefits from memory cells that quickly recognize the antigen, enabling a faster and more potent immune response. Choices A, B, and D are incorrect. While macrophages play a role in presenting antigens to T cells, this is not a defining difference between primary and secondary responses. Humoral immunity involves B lymphocytes in both primary and secondary responses, so it does not differentiate the two. Suppressor T cells primarily function to regulate the immune response but are not a key factor distinguishing primary from secondary responses.

2. What is the difference between DNA and RNA?

• A. Both are double-stranded.
• B. DNA contains deoxyribose sugar, while RNA contains ribose sugar.
• C. RNA contains the nitrogenous base uracil, while DNA contains thymine.
• D. Both are identical molecules.

Correct answer: B

Rationale: A) Incorrect. DNA is double-stranded, but RNA is typically single-stranded. B) Correct. DNA contains deoxyribose sugar, which lacks an oxygen atom on the 2' carbon of the sugar ring, while RNA contains ribose sugar, which has an additional hydroxyl group on the 2' carbon. C) Incorrect. RNA contains the nitrogenous base uracil, while DNA contains thymine. D) Incorrect. DNA and RNA have distinct structures and functions, so they are not identical molecules.

3. Which structure in the respiratory system is responsible for the exchange of oxygen and carbon dioxide between the lungs and the bloodstream?

• A. Trachea
• B. Bronchi
• C. Alveoli
• D. Bronchioles

Correct answer: C

Rationale: The alveoli are tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide occurs. Oxygen from the air diffuses into the bloodstream through the alveoli, while carbon dioxide from the bloodstream diffuses into the alveoli to be exhaled. The trachea, bronchi, and bronchioles are essential parts of the airway system responsible for transporting air to and from the lungs but do not directly participate in the gas exchange process. Therefore, option C, the alveoli, is the correct answer for the structure responsible for the exchange of oxygen and carbon dioxide between the lungs and the bloodstream.

4. Which of the following organs is NOT part of the circulatory system?

• A. Kidneys
• B. Heart
• C. Blood
• D. Blood vessels

Correct answer: A

Rationale: The correct answer is A: Kidneys. The kidneys are not part of the circulatory system. While the circulatory system includes the heart, blood, and blood vessels (arteries, veins, capillaries), the kidneys belong to the urinary system. The kidneys are responsible for filtering waste products from the blood and producing urine. Choice B, the heart, is a vital organ in the circulatory system responsible for pumping blood. Choice C, blood, is a key component of the circulatory system that carries oxygen and nutrients to the body's tissues. Choice D, blood vessels (arteries, veins, capillaries), facilitate the circulation of blood throughout the body, playing a crucial role in the circulatory system.

5. During a scientific investigation, what is intentionally changed or manipulated?

• A. The dependent variable.
• B. The control.
• C. The hypothesis.
• D. The independent variable.

Correct answer: D

Rationale: During a scientific investigation, the independent variable is intentionally changed or manipulated by the researcher to observe its impact or effect on the dependent variable. The independent variable is the one being tested or studied to see how it influences the dependent variable. In contrast, the dependent variable is the outcome or response that is measured in an experiment and is expected to change as a result of the manipulation of the independent variable. Choices A, B, and C are not directly altered during a scientific investigation but play different roles in the research process. Therefore, the correct answer is D - the independent variable.

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