阿摩線上測驗
68. In the cells of the nervous system, which one is the correct description?
(A) Ionotropic receptors act by activating G proteins in target cells.
(B) Metabotropic receptors act by initiating changes in second messenger systems in target cells.
(C) Action potentials are typically also graded potentials.
(D) Electrical synapses transmit signals using neurotransmitters.
(E) Most of the cells in your brain are neurons.
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統計： A(4), B(39), C(4), D(6), E(12) #944368
統計： A(4), B(39), C(4), D(6), E(12) #944368
詳解 (共 4 筆)
突破刑場 締造屬於自己的主場
#6489182
(A) Ionotropic receptors 是離子通道受器（如NMDA receptor），當神經傳導物質結合時，會直接開啟離子通道，不牽涉 G protein。
(B) ✅正確。Metabotropic receptors（代謝型受器）作用機制是：當神經傳導物質結合後，活化 G 蛋白，進而啟動次級傳訊系統（second messenger），例如 cAMP、IP3 等。
(C) Graded potentials 是強度可變、傳遞距離短（如突觸電位、感覺電位）；而 Action potentials（動作電位） 是「全有或全無」的反應，強度固定，傳得比較遠。
(D) Electrical synapses 是細胞之間透過gap junctions直接傳遞訊號，不經由神經傳導物質。
(E) 大腦中約有 90% 是 glial cells（神經膠細胞），而非神經元，雖然神經元很關鍵，但數量上並不是最多。
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LALILATA
#6204053
Graded potentials are variable-strength signals that can be conveyed over small distances, whereas action potentials are massive depolarizations that can be transferred over long distances.
Thus, the action potential is not stimulus-dependent and is caused because of depolarization. It can be transferred over long distances. The graded potential, the signal strength that can be transferred only over short distances, is dependent on the stimulus strength.
(C)Difference between action potential and graded potential
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Hen累的考生
#5396980
請問E選項為什麼不能選? 謝謝
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