Nokea
Which type of glial cell provides structural support and insulation for neurons in the central nervous system?
- A. Schwann cells
- B. Astrocytes
- C. Oligodendrocytes
- D. Microglia
Correct Answer: C
Rationale: Oligodendrocytes are a type of glial cell that provides structural support and insulation for neurons in the central nervous system by forming myelin sheaths around axons. Schwann cells (option A) perform a similar function but in the peripheral nervous system. Astrocytes (option B) are involved in providing nutrients to neurons, maintaining the chemical environment, and repairing damage. Microglia (option D) are primarily responsible for immune defense in the central nervous system, not for providing structural support and insulation for neurons.
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Classifications of human tissues exclude:
- A. Epithelial tissue
- B. Nervous tissue
- C. Adipose tissue (a specialized form of connective tissue)
- D. Bony tissue
Correct Answer: D
Rationale: The correct answer is D: Bony tissue. Classifications of human tissues typically include epithelial tissue, nervous tissue, and connective tissue types such as adipose tissue. Bony tissue, also known as bone tissue, is a specialized form of connective tissue that provides structural support and protection for the body. Therefore, it is not excluded from classifications of human tissues. Choices A, B, and C are valid types of human tissues and are correctly included in classifications of human tissues.
What is the net ionic equation for the reaction: 2HCl(aq) + Ba(OH)2(aq) → 2H2O(l) + BaCl2(aq)?
- A. 2H+(aq) + 2OH-(aq) → 2H2O(l)
- B. 2HCl(aq) + Ba(OH)2(aq) → BaCl2(aq) + 2H2O(l)
- C. 2H+(aq) + Ba2+(aq) → Ba2+(aq) + 2H+(aq)
- D. Ba(OH)2(aq) + HCl(aq) → BaCl2(aq) + 2H2O(l)
Correct Answer: A
Rationale: In the given reaction, the complete ionic equation is: 2H+(aq) + 2Cl-(aq) + Ba2+(aq) + 2OH-(aq) → 2H2O(l) + Ba2+(aq) + 2Cl-(aq). Spectator ions (Ba2+ and Cl-) do not participate in the net ionic equation, which simplifies to: 2H+(aq) + 2OH-(aq) → 2H2O(l). This equation represents the significant species involved in the reaction, showcasing the formation of water from the combination of hydrogen ions and hydroxide ions, resulting in the production of water molecules.
How are kidney stones formed?
- A. Due to excess water not being reabsorbed
- B. When minerals crystallize in the urine
- C. When electrolytes become too concentrated
- D. All of the above
Correct Answer: B
Rationale: Kidney stones are formed when minerals in the urine crystallize and stick together to form solid masses. Excess water not being reabsorbed (option A) does not directly contribute to kidney stone formation. Similarly, electrolytes becoming too concentrated (option C) is not a direct cause of kidney stone formation. The correct answer is B because the crystallization of minerals in the urine leads to the formation of kidney stones.
In the cardiovascular system, what does the term 'double circulation' refer to?
- A. The separation of oxygenated and deoxygenated blood flow within the heart.
- B. The regulation of blood pressure through vasoconstriction and vasodilation.
- C. The cyclic contraction and relaxation of the heart muscle.
- D. The existence of two separate circulatory pathways, one for the lungs and one for the body.
Correct Answer: D
Rationale: The term 'double circulation' in the cardiovascular system refers to the existence of two separate circulatory pathways, one for the lungs (pulmonary circulation) and one for the body (systemic circulation). Oxygen-poor blood is pumped from the heart to the lungs for oxygenation, and then oxygen-rich blood is pumped from the lungs back to the heart to be circulated to the rest of the body. Choices A, B, and C are incorrect as they do not accurately describe the concept of 'double circulation.' Choice A refers to the separation of oxygenated and deoxygenated blood within the heart, choice B relates to blood pressure regulation mechanisms, and choice C describes the cardiac muscle's contraction and relaxation, none of which define 'double circulation' in the context of the cardiovascular system.
Bile, a digestive juice, is produced by which organ?
- A. Stomach
- B. Liver
- C. Pancreas
- D. Small intestine
Correct Answer: B
Rationale: Bile is a digestive juice produced by the liver. It is stored in the gallbladder and released into the small intestine to aid in the digestion and absorption of fats. The stomach (Choice A) produces gastric juices, not bile. The pancreas (Choice C) produces digestive enzymes and bicarbonate but not bile. The small intestine (Choice D) is where bile is released to aid in digestion but is not the organ that produces bile.