Nursing Elites

1. How can a single gene mutation lead to multiple phenotypes depending on the organism?

• A. Pleiotropy describes the effect of one gene influencing multiple seemingly unrelated traits.
• B. Epigenetics involves environmental factors modifying gene expression without altering the DNA sequence.
• C. Genetic drift refers to random changes in allele frequencies within a population.
• D. Gene regulation controls the timing and level of gene expression within an organism.

Correct answer: A

Rationale: A single gene mutation can lead to multiple phenotypes through pleiotropy, where one gene influences diverse traits or functions in an organism. This phenomenon occurs when the mutated gene affects different biochemical pathways, developmental processes, or cellular functions, resulting in a cascade of downstream effects that manifest as a variety of phenotypic outcomes. Choice B, epigenetics, involves modifications in gene expression influenced by environmental factors without altering the DNA sequence, which is not directly related to the question about single gene mutations causing multiple phenotypes. Choice C, genetic drift, refers to random changes in allele frequencies within a population, which is unrelated to the impact of a single gene mutation on multiple phenotypes. Choice D, gene regulation, focuses on controlling the timing and level of gene expression within an organism, which is not directly addressing how a single gene mutation can lead to diverse phenotypes.

2. When referring to blood vessel walls, the term 'atherosclerosis' describes:

• A. The abnormal buildup of plaque within the arterial walls.
• B. The inflammation of the inner lining of blood vessels.
• C. The dilation and weakening of a blood vessel wall (aneurysm).
• D. The normal process of blood vessel wall thickening with age.

Correct answer: A

Rationale: The correct answer is A: 'The abnormal buildup of plaque within the arterial walls.' Atherosclerosis is the process where plaque, consisting of fat, cholesterol, calcium, and other substances, accumulates within the arteries. This buildup can lead to the hardening and narrowing of arteries, reducing blood flow and potentially causing severe health issues like heart attacks and strokes. Choice B is incorrect because inflammation of the inner lining of blood vessels is known as vasculitis, not atherosclerosis. Choice C is incorrect as it describes an aneurysm, which is a dilation and weakening of a blood vessel wall, not atherosclerosis. Choice D is incorrect as it describes arteriosclerosis, a process of blood vessel wall thickening with age, which is different from atherosclerosis.

3. Chromatids divide into identical chromosomes and migrate to opposite ends of the cell in which of the following phases of mitosis?

• A. metaphase
• B. anaphase
• C. prophase
• D. telophase

Correct answer: B

Rationale: During anaphase of mitosis, the sister chromatids detach from each other and migrate to opposite poles of the cell. This process ensures that each daughter cell ultimately receives an identical set of chromosomes, as the chromatids separate and become individual chromosomes again. This is a crucial step in ensuring accurate distribution of genetic material during cell division. In metaphase, the chromosomes align at the cell's equator but do not separate yet. Prophase is the phase where chromatin condenses into chromosomes and the nuclear envelope breaks down. Telophase is the final phase where the nuclear envelope reforms around the separated chromosomes.

4. What is the primary function of hematopoietic tissue?

• A. Building and repairing bone
• B. Supporting and connecting tissues
• C. Production of blood cells
• D. Contracting for movement

Correct answer: C

Rationale: The primary function of hematopoietic tissue is the production of blood cells. Hematopoietic tissue, primarily found in the bone marrow, is responsible for generating red blood cells, white blood cells, and platelets. These blood cells are vital for oxygen transport, immune response, and blood clotting. Choices A, B, and D are incorrect as they do not reflect the main function of hematopoietic tissue. Building and repairing bone is primarily carried out by osteoblasts and osteoclasts, supporting and connecting tissues is a role of connective tissues like tendons and ligaments, and contracting for movement is a function of muscle tissue.

5. What is the structure and function of elastic arteries?

• A. They are the smallest arteries and constrict and dilate frequently.
• B. They are medium-sized arteries that distribute blood to various organs.
• C. They are the largest arteries and stretch and recoil to accommodate blood pressure changes.
• D. They are thin-walled arteries that supply blood to the capillaries.

Correct answer: C

Rationale: The corrected answer is C. Elastic arteries, like the aorta, are the largest arteries in the body. They possess elastic fibers in their walls, allowing them to stretch and recoil in response to the pulsatile nature of blood flow from the heart. This elasticity helps to maintain blood pressure by absorbing the pressure waves generated by the heart's contractions and ensuring continuous blood flow to the organs. Choices A, B, and D are incorrect because elastic arteries are not the smallest arteries, do not constrict and dilate frequently, are not medium-sized arteries for distributing blood to various organs, and are not thin-walled arteries supplying blood to capillaries. Elastic arteries have a specific structure and function related to their ability to accommodate blood pressure changes due to their elastic properties, which is essential for the cardiovascular system's proper functioning.

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