Nokea
Through which aspect do afferent fibers enter the spinal cord?
- A. Through the anterior aspect
- B. Through the dorsal aspect
- C. Through the ventral aspect
- D. Through the lateral aspect
Correct Answer: B
Rationale: Afferent fibers, responsible for carrying sensory information, enter the spinal cord through the posterior (dorsal) aspect. Specifically, they enter through the dorsal roots, located on the back (posterior) side of the spinal cord. This route allows sensory information to be transmitted to the central nervous system for processing and integration. Choices A, C, and D are incorrect because afferent fibers do not enter the spinal cord through the anterior, ventral, or lateral aspects.
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What is the main role of the large intestine in digestion?
- A. Absorbing proteins
- B. Absorbing carbohydrates
- C. Absorbing fats
- D. Absorbing water
Correct Answer: D
Rationale: The main role of the large intestine in digestion is to absorb water. When food reaches the large intestine, most nutrients have already been absorbed by the small intestine. In the large intestine, water is absorbed from the remaining undigested food, helping to form solid waste (feces). Absorbing proteins, carbohydrates, or fats primarily occurs in the small intestine, not in the large intestine. Therefore, options A, B, and C are incorrect.
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.
What is the electrical charge of the nucleus?
- A. A nucleus always has a positive charge.
- B. A stable nucleus has a positive charge, but a radioactive nucleus may have no charge and instead be neutral.
- C. A nucleus always has no charge and is instead neutral.
- D. A stable nucleus has no charge and is instead neutral, but a radioactive nucleus may have a charge.
Correct Answer: A
Rationale: A nucleus always has a positive charge. This is because the nucleus is composed of positively charged protons, along with neutral neutrons. The positive charge of the protons is balanced by the negative charge of the surrounding electrons in an atom, resulting in an overall neutral charge for the atom as a whole. Therefore, choice A is correct as it accurately reflects the positive charge of the nucleus due to the presence of protons. Choices B, C, and D are incorrect because they do not accurately represent the fundamental composition and charge distribution within an atom's nucleus. A stable nucleus consists of positively charged protons and neutral neutrons, leading to an overall positive charge, and not a neutral charge as suggested in the incorrect choices.
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.
Which of the following terms describes stem cells that have the ability to develop into any cell found in the human body?
- A. Totipotent stem cells
- B. Multipotent stem cells
- C. Pluripotent stem cells
- D. Hematopoietic stem cells
Correct Answer: A
Rationale: Totipotent stem cells have the unique ability to differentiate into any cell type in the human body and can generate a complete organism. They are considered the most versatile type of stem cells, capable of developing into all cell types, including extraembryonic tissues. Choice A, Totipotent stem cells, is the correct answer as it specifically describes stem cells with the broadest differentiation potential. Choice B, Multipotent stem cells, refers to stem cells that can differentiate into a limited range of cell types. Choice C, Pluripotent stem cells, can give rise to almost all cell types, but not the complete organism like totipotent stem cells. Choice D, Hematopoietic stem cells, are a type of multipotent stem cells that give rise to various blood cell types, but do not have the same broad differentiation potential as totipotent stem cells.