Nursing Elites

1. 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.

2. Which of the following correctly describes mitosis?

• A. Mitosis occurs in germ cells.
• B. Mitosis occurs in somatic cells.
• C. Mitosis involves the reduction of chromosome number by half.
• D. Mitosis produces four genetically different cells.

Correct answer: B

Rationale: The correct answer is B. Mitosis occurs in somatic cells where a single cell divides to produce two identical daughter cells. Germ cells undergo meiosis, not mitosis. Choice C is incorrect as mitosis results in the preservation of the same chromosome number in daughter cells. Choice D is inaccurate as mitosis produces genetically identical cells, not genetically different ones.

3. At which of the following ages would ossification most likely take place to replace cartilage at the growth plate?

• A. 5
• B. 18
• C. 42
• D. 91

Correct answer: B

Rationale: Ossification, the process where cartilage is replaced by bone, typically occurs during adolescence, around the age of 18. This is when the growth plates in the bones close, and the bones stop growing in length, leading to the replacement of cartilage with bone tissue. Choice A (5) is incorrect because ossification primarily occurs during adolescence, not early childhood. Choice C (42) is incorrect as ossification is completed well before this age, usually during the late teens or early twenties. Choice D (91) is incorrect as ossification is a process that occurs earlier in life, typically during adolescence, and is not a process that occurs in advanced age.

4. What is the definition of the term 'momentum' in physics?

• A. Force exerted on an object
• B. Speed of an object in motion
• C. Mass in motion
• D. Distance traveled per unit time

Correct answer: C

Rationale: Momentum in physics is the product of an object's mass and its velocity. It is a vector quantity that describes the motion of an object and is given by the formula p = mv, where p is momentum, m is mass, and v is velocity. Therefore, momentum is best described as the mass of an object in motion. Choice A, 'Force exerted on an object,' is incorrect because force is not equivalent to momentum. Choice B, 'Speed of an object in motion,' is incorrect because speed only considers the rate of motion and not the mass aspect. Choice D, 'Distance traveled per unit time,' is incorrect as it relates to speed and not momentum, which involves both mass and velocity.

5. How do spindle fiber dynamics and microtubule attachment regulate cell cycle checkpoints?

• A. Misaligned chromosomes fail to attach to microtubules, triggering a delay in anaphase onset.
• B. The presence of unattached kinetochores on the centromeres sends a signal to pause cell cycle progression.
• C. Microtubule instability and rapid depolymerization lead to the activation of checkpoint proteins.
• D. All of the above.

Correct answer: D

Rationale: A) Misaligned chromosomes fail to attach to microtubules, triggering a delay in anaphase onset: Proper attachment of chromosomes to spindle fibers is essential for accurate segregation of genetic material during cell division. Misaligned chromosomes that fail to attach to microtubules can lead to delays in anaphase onset, allowing the cell to correct errors before proceeding with division. B) The presence of unattached kinetochores on the centromeres sends a signal to pause cell cycle progression: Kinetochores at the centromeres help attach chromosomes to spindle fibers. When kinetochores are unattached or improperly attached to microtubules, they signal the cell to pause cell cycle progression, ensuring proper chromosome alignment before division. C) Microtubule instability and rapid depolymerization lead to the activation of checkpoint proteins: While microtubule dynamics are crucial for cell division, microtubule instability and rapid depolymerization can disrupt chromosome attachment. However, this mechanism is not directly related to the activation of cell cycle checkpoint proteins, making this statement incorrect. Therefore, choices A and B accurately describe how spindle fiber dynamics and microtubule attachment regulate cell cycle checkpoints, making option D the correct answer.

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