Nokea
How does lymph move through the lymphatic vessels?
- A. By the pumping action of the heart
- B. Due to muscle contractions and breathing movements
- C. Through one-way valves within the vessels
- D. All of the above
Correct Answer: C
Rationale: Lymph moves through the lymphatic vessels due to the presence of one-way valves within the vessels. These valves prevent the backflow of lymph and help propel the fluid forward as muscles contract and relax or due to breathing movements. Unlike blood circulation, the lymphatic system does not rely on the pumping action of the heart to move lymph. Choice A is incorrect because lymphatic circulation does not depend on the pumping action of the heart. Choice B is partly correct as muscle contractions and breathing movements do assist in propelling lymph, but the primary mechanism is the presence of one-way valves within the vessels, making choice C the most accurate answer. Choice D is incorrect as not all options listed contribute to how lymph moves through the lymphatic vessels.
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Which of the following is a MAJOR consequence of a stroke?
- A. Irregular heart rhythm.
- B. Rapid weight gain or loss.
- C. Brain damage due to interrupted blood flow.
- D. Chronic fatigue and muscle weakness.
Correct Answer: C
Rationale: A major consequence of a stroke is brain damage due to interrupted blood flow. Strokes occur when blood flow to the brain is blocked or reduced, leading to the death of brain cells. This interruption in blood flow results in brain damage, which can cause physical and cognitive impairments such as paralysis, speech difficulties, memory problems, and sensory disturbances. The severity and location of the stroke determine the extent of the consequences experienced by the individual. Choices A, B, and D are incorrect. Irregular heart rhythm is not a direct consequence of a stroke but may occur as a complication. Rapid weight gain or loss and chronic fatigue with muscle weakness are not typically considered major consequences of a stroke, which primarily affects the brain due to interrupted blood flow.
Which of the following is an example of a commensal relationship between a microorganism and a human?
- A. Salmonella causing food poisoning
- B. taphylococcus aureus causing skin infections
- C. coli living in the gut
- D. Rabies virus causing neurological disease
Correct Answer: C
Rationale: A commensal relationship is a type of symbiotic relationship in which one organism benefits, while the other is neither harmed nor benefited. In this case, E. coli living in the gut is an example of a commensal relationship because it can benefit from the environment in the gut without causing harm to the human host.
Option A, Salmonella causing food poisoning, is an example of a pathogenic relationship where the microorganism causes harm to the host. Option B, Staphylococcus aureus causing skin infections, is also an example of a pathogenic relationship where the microorganism causes harm to the host. Option D, Rabies virus causing neurological disease, is another example of a pathogenic relationship where the microorganism causes harm to the host.
Passive transport does not require energy input from the cell. Which of the following is an example of passive transport?
- A. Active transport of ions across a membrane
- B. Diffusion of small molecules across a concentration gradient
- C. Movement of large molecules using vesicles
- D. Endocytosis of particles into the cell
Correct Answer: B
Rationale: Passive transport refers to the movement of molecules across a cell membrane without the input of energy. Diffusion of small molecules across a concentration gradient is a classic example of passive transport, as it occurs spontaneously from an area of high concentration to an area of low concentration. Active transport (option A) requires energy input in the form of ATP to move substances against their concentration gradient. Movement of large molecules using vesicles (option C) involves processes like endocytosis and exocytosis that require energy in the form of ATP. Endocytosis of particles into the cell (option D) is an active process that requires energy expenditure by the cell to engulf and internalize extracellular substances.
What does the innate immune system provide?
- A. Nonspecific, immediate defense against pathogens
- B. Specific, long-term immune response through memory cells
- C. Both (a) and (b)
- D. Neither (a) nor (b)
Correct Answer: A
Rationale: The correct answer is A. The innate immune system provides nonspecific, immediate defense against pathogens. It is the body's first line of defense in responding to infections and does not involve memory cells or specific long-term immune responses like the adaptive immune system. Choice B is incorrect because specific, long-term immune responses through memory cells are characteristics of the adaptive immune system, not the innate immune system. Choice C is incorrect because the innate immune system does not provide specific, long-term immune responses. Choice D is incorrect because the innate immune system does provide an immediate defense against pathogens.
What is the product of the complete combustion of propane (C3H8)?
- A. CO2
- B. CO
- C. CH4
- D. C
Correct Answer: A
Rationale: The complete combustion of propane (C3H8) results in the production of carbon dioxide (CO2) and water. When a hydrocarbon such as propane undergoes complete combustion, the carbon atoms combine with oxygen to form CO2. This makes choice A, CO2, the correct answer. Choices B, C, and D are incorrect as CO is carbon monoxide, CH4 is methane, and C is elemental carbon, none of which are the primary product of the complete combustion of propane.