Nokea
What is the most powerful stimulus for breathing in a healthy person?
- A. Acidosis
- B. Alkalosis
- C. Increase in CO2
- D. Loss of O2
Correct Answer: C
Rationale: The correct answer is an increase in CO2. In a healthy individual, the primary drive to breathe is regulated by the levels of carbon dioxide (CO2) in the blood. When CO2 levels increase, it triggers the body to increase the rate and depth of breathing to eliminate excess CO2 and restore the balance. This response is more powerful than other stimuli such as acidosis, alkalosis, or loss of oxygen. While acidosis and alkalosis can affect breathing, an increase in CO2 has a more direct and immediate impact. Loss of oxygen (hypoxia) is a potent stimulus, but the body's response to increased CO2 levels is generally more pronounced and immediate in healthy individuals.
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What type of cells compose the epidermis?
- A. Osteoclasts
- B. Connective
- C. Dendritic
- D. Epithelial
Correct Answer: D
Rationale: The correct answer is D: Epithelial. The epidermis is composed of epithelial cells, specifically called keratinocytes, which are responsible for producing keratin, a protein that provides the skin with strength and flexibility. Epithelial cells form the protective outer layer of the skin and play a crucial role in skin repair and regeneration.
Choice A - Osteoclasts are cells involved in bone remodeling, not found in the epidermis.
Choice B - Connective tissue cells are not the primary cells found in the epidermis. They are more commonly found in the dermis, providing structural support and elasticity to the skin.
Choice C - Dendritic cells are part of the immune system and are present in the skin to help recognize pathogens and activate the immune response. However, they are not the main cell type that composes the epidermis.
What breaks down into glucose to provide energy?
- A. Lipids
- B. Proteins
- C. Carbohydrates
- D. Nucleic acids
Correct Answer: C
Rationale: Carbohydrates are broken down into glucose during digestion, providing energy for cellular processes through glycolysis and cellular respiration. Glucose is a primary source of energy for cells, and its breakdown is essential for powering various cellular activities. Lipids are broken down into fatty acids and glycerol, not glucose. Proteins are broken down into amino acids and are not a direct source of glucose. Nucleic acids are not broken down into glucose for energy production.
Which type of capillary is the most common and least permeable?
- A. Fenestrated capillaries
- B. Sinusoidal capillaries
- C. Continuous capillaries
- D. Discontinuous capillaries
Correct Answer: C
Rationale: The correct answer is C, continuous capillaries. Continuous capillaries are the most common and least permeable type of capillary. They are found in most tissues, including muscle and the nervous system. Continuous capillaries have a continuous endothelium without fenestrations or large gaps, which limits the movement of substances across their walls.
Choice A, fenestrated capillaries, have pores (fenestrations) in their endothelial cells, making them more permeable than continuous capillaries.
Choice B, sinusoidal capillaries, have a discontinuous endothelium with large gaps between cells, making them more permeable and allowing larger molecules and cells to pass through compared to continuous capillaries.
Choice D, discontinuous capillaries, are similar to sinusoidal capillaries with a discontinuous endothelium, allowing for enhanced permeability compared to continuous capillaries.
What is a submicroscopic entity that is considered nonliving because it lacks cellular structure and consists of nucleic acids encapsulated in a protein coat called a capsid?
- A. Bacteria
- B. Fungus
- C. Virus
- D. Protozoa
Correct Answer: C
Rationale: The correct answer is C: Virus. Viruses are not considered living organisms because they lack cellular structure. Instead, they are composed of nucleic acids (either DNA or RNA) enclosed in a protein coat called a capsid. Bacteria (choice A), fungus (choice B), and protozoa (choice D) are all living organisms with cellular structures, unlike viruses. Therefore, they are incorrect choices for this question.
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.