Nokea
The outermost layer of your skin, responsible for waterproofing and providing a barrier against pathogens, is the:
- A. Stratum basale (Basal layer)
- B. Stratum corneum
- C. Stratum granulosum
- D. Stratum spinosum
Correct Answer: B
Rationale: The correct answer is B: Stratum corneum. The stratum corneum is the outermost layer of the epidermis, consisting of dead skin cells that are constantly shed and replaced. It serves as a protective barrier against pathogens and helps to prevent water loss from the body. Choice A, Stratum basale, is the deepest layer of the epidermis where new skin cells are produced. Choice C, Stratum granulosum, is a layer of the epidermis where the cells begin to flatten and lose their nuclei. Choice D, Stratum spinosum, is a layer of the epidermis where cells become irregular in shape and have spiny projections.
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What is the process by which a cell divides into two or more new cells?
- A. Mitosis
- B. Meiosis
- C. Both mitosis and meiosis
- D. None of the above
Correct Answer: A
Rationale: Mitosis is the process by which a cell divides into two identical daughter cells. This type of cell division is essential for growth, repair, and maintenance of multicellular organisms. Meiosis, on the other hand, is a type of cell division that produces gametes (sperm and egg cells) with half the number of chromosomes as the parent cell. Meiosis does not directly result in the formation of new cells, as it is specifically geared towards the production of reproductive cells. Therefore, the correct answer is A. Option C, stating both mitosis and meiosis, is incorrect because meiosis is not involved in the general process of cell division to produce new cells; it is specialized for gamete formation. Option D is incorrect because mitosis is indeed the process responsible for cell division in which one cell divides into two daughter cells, making it the accurate choice for this question.
What is the function of the pericardium, the sac surrounding the heart?
- A. To generate electrical impulses for heart contraction
- B. To transport blood throughout the body
- C. To provide lubrication for heart movement
- D. To protect the heart and anchor it in place
Correct Answer: C
Rationale: The pericardium is a double-walled sac that surrounds the heart and contains a small amount of fluid to provide lubrication for the movement of the heart within the chest cavity. It helps reduce friction as the heart beats and moves. Choice A is incorrect because the generation of electrical impulses for heart contraction is primarily the function of the heart's specialized conduction system. Choice B is incorrect as the pericardium is not involved in the transportation of blood throughout the body. Choice D is also incorrect as while the pericardium does protect the heart, its primary function is to provide lubrication and reduce friction.
When an atom gains or loses electrons, it becomes a(n):
- A. Molecule
- B. Isotope
- C. Ion
- D. Compound
Correct Answer: C
Rationale: When an atom gains or loses electrons, it becomes an ion. Gaining or losing electrons alters the atom's electron count and charge, creating a positively or negatively charged ion. A molecule is formed when two or more atoms are chemically bonded. An isotope is a variation of an element with a different number of neutrons. A compound consists of two or more different elements chemically bonded together.
Which hormone, produced by the thyroid gland, plays a crucial role in regulating the body's metabolism, growth, and development?
- A. Calcitonin
- B. Parathyroid hormone (PTH)
- C. Thyroxine
- D. Insulin
Correct Answer: C
Rationale: Thyroxine, also known as T4, is a hormone produced by the thyroid gland that plays a crucial role in regulating the body's metabolism, growth, and development. It helps control the rate at which the body uses energy, affects protein synthesis, and influences the body's sensitivity to other hormones. Calcitonin (A) is another hormone produced by the thyroid gland, but its primary function is to regulate calcium levels in the blood. Parathyroid hormone (PTH) (B) is produced by the parathyroid glands and is involved in regulating calcium and phosphorus levels in the body. Insulin (D) is a hormone produced by the pancreas that helps regulate blood sugar levels.
The Becquerel (Bq) is the designated unit for quantifying:
- A. Electron volt (eV) measurements of energy
- B. Radioactivity
- C. Electric charge (Coulombs)
- D. Force (Newtons)
Correct Answer: B
Rationale: The Becquerel (Bq) is the unit used to measure radioactivity, specifically the activity of a quantity of radioactive material. It represents the number of radioactive disintegrations or transformations per unit of time. Choice A, electron volt (eV), is a unit of energy, not radioactivity. Choice C, electric charge (Coulombs), is measured in Coulombs, not Becquerels. Choice D, force (Newtons), is a unit of force, not radioactivity. Therefore, the correct answer is B.