Nokea
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.
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Which structure of the respiratory system bifurcates into the primary bronchi?
- A. Trachea
- B. Alveoli
- C. Bronchioles
- D. Larynx
Correct Answer: A
Rationale: The trachea is the structure that bifurcates into the primary bronchi. The trachea is a tube that carries air to and from the lungs. It divides into the left and right primary bronchi at a specific point called the carina, which then further divide into secondary and tertiary bronchi, leading to the bronchioles. The alveoli are the tiny air sacs at the end of the bronchioles where gas exchange occurs, not the structure that bifurcates into the primary bronchi. Bronchioles are smaller airway branches that come after the bronchi but do not bifurcate into them. The larynx, also known as the voice box, is located above the trachea and is responsible for sound production, not the bifurcation into primary bronchi. Therefore, the correct answer is the trachea.
Which cellular organelle is used for digestion to recycle materials?
- A. The Golgi apparatus
- B. The lysosome
- C. The centrioles
- D. The mitochondria
Correct Answer: B
Rationale: The lysosome is the correct cellular organelle used for digestion to recycle materials. Lysosomes contain enzymes that break down waste materials, cellular debris, and ingested substances. This process helps in recycling nutrients and maintaining cellular homeostasis. The Golgi apparatus is involved in processing and packaging proteins, the centrioles play a role in cell division, and the mitochondria are responsible for energy production. However, none of these organelles are primarily used for digestion and recycling of materials within the cell.
What happens to the diaphragm during inspiration?
- A. It moves upward
- B. It moves downward
- C. It expands
- D. It contracts and moves downward
Correct Answer: D
Rationale: During inspiration, the diaphragm contracts and moves downward. This action increases the volume of the thoracic cavity, which lowers the air pressure inside the lungs, allowing air to flow in. The downward movement and contraction of the diaphragm create the necessary space for the lungs to expand and fill with air. Choice A, 'It moves upward,' is incorrect as the diaphragm moves downward. Choice B, 'It moves downward,' is partially correct but misses the contraction aspect. Choice C, 'It expands,' is incorrect as the diaphragm itself does not expand during inspiration. Therefore, choice D, 'It contracts and moves downward,' is the most accurate description of the diaphragm's action during inspiration.
What term describes the front of the body, for example, the kneecap?
- A. Posterior
- B. Anterior
- C. Superior
- D. Inferior
Correct Answer: B
Rationale: The correct answer is 'B: Anterior.' In anatomy, 'anterior' refers to the front of the body, like the kneecap. On the other hand, 'posterior' describes the back of the body. Choices 'C: Superior' and 'D: Inferior' relate to structures being above or below a reference point, respectively, and are not used to describe the front or back of the body. Therefore, 'Anterior' is the most appropriate term given the context provided in the question.
What cells compose the epidermis?
- A. Keratinocytes
- B. Epithelial cells
- C. Fibroblasts
- D. Melanocytes
Correct Answer: A
Rationale: The correct answer is A - Keratinocytes. The epidermis is primarily composed of keratinocytes, which are a type of epithelial cell. Keratinocytes synthesize the protein keratin, providing protection against physical damage and water loss. While epithelial cells are correct, specifying keratinocytes is more precise. Fibroblasts are not the main cell type in the epidermis; they are found in the dermis, where they produce collagen and other extracellular matrix components. Melanocytes are responsible for producing melanin pigment in the skin and are also present in the epidermis, but they are not the predominant cell type like keratinocytes.