Nokea
What is the first event to occur in a primary immune response?
- A. Macrophages phagocytose pathogens and present their antigens.
- B. Neutrophils aggregate and act as cytotoxic, nonspecific killers of pathogens.
- C. B lymphocytes make pathogen-specific antibodies.
- D. Helper T cells secrete interleukins to activate pathogen-fighting cells.
Correct Answer: A
Rationale: The correct answer is A. The initial event in a primary immune response is the phagocytosis of pathogens by macrophages and the subsequent presentation of their antigens, which is crucial for initiating the adaptive immune response. Neutrophils (Choice B) are also involved in the innate immune response, but they typically respond after macrophages. B lymphocytes (Choice C) produce antibodies later in the adaptive immune response, and Helper T cells (Choice D) help in coordinating the immune response but are not the first cells to act in a primary immune response.
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How many neurons typically comprise a sensory pathway?
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: C
Rationale: A sensory pathway generally consists of three neurons: a first-order neuron, a second-order neuron, and a third-order neuron. The first-order neuron carries sensory information from the periphery to the spinal cord or brainstem. The second-order neuron then transmits this information to the thalamus or cerebellum. Finally, the third-order neuron projects the sensory input to the cerebral cortex for processing and perception. Therefore, the correct answer is 3 (C). Choices A, B, and D are incorrect as they do not align with the typical structure of a sensory pathway involving three neurons.
What do nociceptors detect?
- A. Deep pressure
- B. Vibration
- C. Pain
- D. Temperature
Correct Answer: C
Rationale: Nociceptors are specialized sensory receptors that detect and transmit signals related to pain. These receptors are activated by noxious stimuli that can potentially cause tissue damage or injury, triggering the perception of pain in the brain. Therefore, the correct answer is 'Pain.' Choices A, B, and D are incorrect because nociceptors specifically respond to painful stimuli, not deep pressure, vibration, or temperature.
How do organisms maintain homeostasis?
- A. By increasing their body temperature, blood pH, and fluid balance.
- B. By undergoing biochemical processes and absorbing energy to increase entropy.
- C. By undergoing biochemical processes to maintain the order of their external environment.
- D. By using free energy and matter via biochemical processes to work against entropy.
Correct Answer: D
Rationale: Organisms maintain homeostasis by utilizing free energy and matter through biochemical processes to counteract entropy, which helps in preserving internal stability. This process involves maintaining a balance within the organism's internal environment despite external changes, ensuring proper functioning and survival. Choice A is incorrect because increasing body temperature, blood pH, and fluid balance alone do not define the comprehensive process of maintaining homeostasis. Choice B is incorrect as absorbing energy to increase entropy goes against the concept of maintaining internal stability. Choice C is incorrect as maintaining the order of the external environment does not directly contribute to the organism's internal stability and balance.
Which of the following statements about the autonomic nervous system (ANS) is true?
- A. It controls involuntary functions
- B. It contains motor (efferent) neurons
- C. It contains sensory (afferent) neurons
- D. It contains both parasympathetic and sympathetic nerves
Correct Answer: D
Rationale: The correct answer is D because the autonomic nervous system (ANS) is responsible for controlling involuntary functions and contains both parasympathetic and sympathetic nerves. Choices A and B are incorrect as they do not fully capture the role of the ANS. While the ANS does control involuntary functions, this is a broader concept than just the reflex arc. While the ANS does contain motor (efferent) neurons, it also includes sensory (afferent) neurons, which are not specifically mentioned in the question. Therefore, choice C is not fully accurate. Choice D provides the most accurate and comprehensive description of the autonomic nervous system by highlighting its components, the parasympathetic and sympathetic nerves, which work together to regulate various bodily functions.
Which of the following touch receptors respond to light touch and slower vibrations?
- A. Merkel's discs
- B. Pacinian corpuscles
- C. Meissner's corpuscles
- D. Ruffini endings
Correct Answer: A
Rationale: The correct answer is A, Merkel's discs. Merkel's discs are touch receptors that respond to light touch and slower vibrations, making them ideal for detecting subtle tactile stimuli. Pacinian corpuscles are specialized in detecting deep pressure and high-frequency vibrations, not light touch or slower vibrations. Meissner's corpuscles, on the other hand, are sensitive to light touch and low-frequency vibrations, but they do not specifically respond to slower vibrations. Ruffini endings are responsible for detecting skin stretch and continuous touch pressure, differentiating them from Merkel's discs, which are specifically attuned to light touch and slower vibrations.