Nokea
Which of the following layers of skin acts as an energy reserve by storing adipocytes and releasing them into circulation when energy is needed?
- A. epidermis
- B. dermis
- C. hypodermis
- D. stratum basale
Correct Answer: C
Rationale: The hypodermis, also known as the subcutaneous tissue, is the deepest layer of the skin. This layer contains adipocytes (fat cells) that act as an energy reserve by storing excess energy in the form of fat. When energy is needed, these stored fats can be released into circulation to be used by the body's cells. The epidermis is the outermost layer of the skin, primarily responsible for providing a protective barrier. The dermis lies between the epidermis and hypodermis and contains blood vessels, nerves, and structures like hair follicles and sweat glands. The stratum basale is the deepest layer of the epidermis, responsible for cell renewal and regeneration.
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Which of the following describes the general function of cytokines in the immune system?
- A. They communicate between cells to instigate an immune response.
- B. They inhibit blood clotting during inflammation responses.
- C. They bind to specific pathogens to increase pathogen mass.
- D. They transport pathogens trapped in mucus to be destroyed in the stomach.
Correct Answer: A
Rationale: The correct answer is A: 'They communicate between cells to instigate an immune response.' Cytokines are signaling molecules that act as messengers between cells in the immune system, playing a vital role in coordinating and regulating immune responses. They communicate with various immune cells to initiate appropriate responses against pathogens. Choice B is incorrect because cytokines do not inhibit blood clotting but rather regulate immune responses. Choice C is incorrect as cytokines do not bind to specific pathogens to increase their mass; instead, they regulate the immune response. Choice D is also incorrect because cytokines do not transport pathogens trapped in mucus to the stomach for destruction; they primarily function as signaling molecules within the immune system.
Which of the following sets of valves is primarily responsible for preventing blood flow from major blood vessels to the heart?
- A. atrioventricular valves
- B. semilunar valves
- C. tricuspid valves
- D. bicuspid valves
Correct Answer: B
Rationale: The correct answer is B: semilunar valves. Semilunar valves are primarily responsible for preventing blood flow from major blood vessels to the heart. These valves are located at the base of the aorta and the pulmonary artery, ensuring blood flows in one direction only by closing when the ventricles relax to prevent blood from flowing back into the heart. Choices A, C, and D are incorrect. Atrioventricular valves (choice A) include the tricuspid and bicuspid valves, which prevent backflow between the atria and ventricles, not major blood vessels. Tricuspid valves (choice C) and bicuspid valves (choice D) are specific types of atrioventricular valves located between the atria and ventricles, not at the base of major blood vessels.
Which of the following are the blood vessels that transport blood away from the heart?
- A. arteries
- B. capillaries
- C. venules
- D. veins
Correct Answer: A
Rationale: Arteries are blood vessels that carry oxygen-rich blood away from the heart to various parts of the body. Therefore, they are the vessels that transport blood away from the heart. Veins, on the other hand, transport blood back to the heart. Capillaries are tiny blood vessels where the exchange of nutrients and waste products occurs between blood and tissues, not vessels that transport blood to the heart. Venules are small veins that collect blood from capillaries and connect them to larger veins, rather than transport blood to the heart.
Which of the following is NOT a function of the liver?
- A. nutrient processing
- B. blood filtration and detoxification
- C. cholesterol and lipoprotein production
- D. insulin production and blood sugar regulation
Correct Answer: D
Rationale: The correct answer is D. The liver does not produce insulin; instead, insulin is produced by the pancreas. The liver plays a crucial role in regulating blood sugar levels by storing and releasing glucose but does not directly produce insulin. Choices A, B, and C are functions of the liver. Nutrient processing, blood filtration, detoxification, cholesterol, and lipoprotein production are essential roles performed by the liver to maintain overall metabolic balance and health.
Which of the following basic mechanisms of evolution is described as the process where organisms with an advantageous trait survive more often and produce more offspring than organisms without the advantageous trait?
- A. gene flow
- B. genetic drift
- C. mutation
- D. natural selection
Correct Answer: D
Rationale: Natural selection is the basic mechanism of evolution that explains how organisms with advantageous traits are more likely to survive and reproduce in a given environment. This leads to the passing on of these favorable traits to their offspring, causing these traits to become more common in the population over time, resulting in evolutionary change. Natural selection is driven by environmental pressures that support the survival and reproduction of individuals with specific traits. Gene flow refers to the movement of genes between populations, genetic drift is the change in allele frequencies due to random events, and mutation is the source of genetic variation but is not the process by which advantageous traits become more prevalent in a population.