Nursing Elites

1. What are the tiny contractile units within muscle cells called?

• A. Myocytes
• B. Myofibrils
• C. Sarcomeres
• D. Tendons

Correct answer: C

Rationale: Sarcomeres are the smallest contractile units within muscle cells. They consist of overlapping filaments of actin and myosin proteins, which interact to produce muscle contractions. Myocytes are the entire muscle cells, myofibrils are bundles of protein filaments found within muscle cells, and tendons are tough connective tissues that connect muscles to bones. Therefore, sarcomeres specifically represent the contractile units responsible for muscle contraction, making them the correct answer in this context.

2. What is the difference between polygenic inheritance and pleiotropy?

• A. Polygenic inheritance involves multiple genes influencing one trait, while pleiotropy involves one gene affecting multiple traits.
• B. Polygenic inheritance is found in simple Mendelian traits, while pleiotropy is found in complex traits.
• C. Polygenic inheritance is always quantitative, while pleiotropy can be qualitative or quantitative.
• D. Both involve multiple genes and multiple traits, but the specific mechanisms differ

Correct answer: A

Rationale: - Polygenic inheritance refers to the situation where a trait is influenced by multiple genes, each contributing a small effect to the phenotype. These traits often show continuous variation and are not easily categorized into discrete categories. - Pleiotropy, on the other hand, occurs when a single gene influences multiple, seemingly unrelated traits. This means that a mutation in one gene can lead to multiple phenotypic effects across different traits or characteristics. - Therefore, the key difference between polygenic inheritance and pleiotropy lies in the number of genes involved in influencing a trait (multiple genes in polygenic inheritance vs. one gene in pleiotropy) and the direction of influence (one trait affected by multiple genes in polygenic inheritance vs. multiple traits affected by one gene in pleiotropy).

3. Which statement accurately describes cytokinesis in animal cells?

• A. Which statement accurately describes cytokinesis in animal cells?
• B. A cell plate forms in the center of the dividing cell, eventually separating the cytoplasm into two daughter cells.
• C. A cell plate forms in the center of the dividing cell, eventually separating the cytoplasm into two daughter cells.
• D. The nucleus elongates and pulls apart, physically dividing the cytoplasm into two.

Correct answer: B

Rationale: A) This statement is a duplicate of option C and does not accurately describe cytokinesis in animal cells. B) In animal cells, during cytokinesis, a cleavage furrow forms in the center of the dividing cell. This furrow deepens and eventually pinches the cytoplasm into two daughter cells. This process is distinct from plant cells, where a cell plate forms. C) This statement is a duplicate of option A and does not accurately describe cytokinesis in animal cells. D) This statement describes the process of nuclear division (mitosis) rather than cytokinesis, which is the division of the cytoplasm.

4. Which of the following is NOT a major function of the respiratory system in humans?

• A. It provides a large surface area for gas exchange of oxygen and carbon dioxide.
• B. It helps regulate the blood's pH.
• C. It helps cushion the heart against jarring motions.
• D. It is responsible for vocalization.

Correct answer: C

Rationale: Option C, 'It helps cushion the heart against jarring motions,' is NOT a major function of the respiratory system in humans. The primary functions of the respiratory system include gas exchange, regulation of blood pH, and vocalization. The respiratory system does not play a role in cushioning the heart; that function is primarily carried out by the pericardium and other protective structures around the heart. Choices A, B, and D are major functions of the respiratory system in humans. Choice A refers to the respiratory system's role in gas exchange, Choice B highlights its involvement in regulating blood pH, and Choice D points out its responsibility for vocalization.

5. A rocket engine expels hot gases backwards. What principle explains the rocket's forward motion?

• A. Newton's first law of motion
• B. Newton's second law of motion
• C. Newton's third law of motion
• D. Law of conservation of energy

Correct answer: C

Rationale: Newton's third law of motion states that for every action, there is an equal and opposite reaction. In the case of a rocket engine expelling hot gases backwards, the action is the expulsion of gases, and the reaction is the forward motion of the rocket. The hot gases being expelled act as the action force, propelling the rocket in the opposite direction as the reaction force, resulting in the rocket's forward motion. Newton's first law of motion (Choice A) pertains to inertia, stating that an object in motion will stay in motion unless acted upon by an external force. Newton's second law of motion (Choice B) relates force, mass, and acceleration, which is not directly applicable to the scenario of a rocket engine propulsion. The law of conservation of energy (Choice D) is a fundamental principle stating that energy cannot be created or destroyed but can only be transformed, which does not directly explain the forward motion of the rocket in this context.

Similar Questions