SPM Biology 2017


6. Diagram 6 shows the pathway of nerve impulse in a reflex action.

Rajah 6 menunjukkan laluan impuls saraf dalam suatu tindakan refleks.

(a)(i) Explain the transmission of nerve impulse during reflex action in Diagram 6.

Terangkan penghantaran impuls saraf semasa Tindakan refleks dalam Rajah 6.

(ii) Based on Diagram 6, compare and contrast the afferent neurone and efferent neurone.

Berdasarkan Rajah 6, bandingkan dan bezakan di antara neuron aferen dan neuron eferen.


(b) Depressant is given to a patient to relieve the anxieties in everyday life. Explain the effect of effect of the drugs on the transmission of impulse through synapse. Diagram 7.1 shows body cells and blood vessels.

Dadah penenang diberikan kepada seorng pesakit untuk mengurangkan ketegangan dalam kehidupan seharian. Terangkan kesan dadah tersebut ke atas penghantaran impuls melalui sinaps. Rajah 7.1 menunjukkan sel badan salur darah.

Cher Questions Solution Bank Rumusan Jawapan SPM & IGCSE Questions Answers Solution

Cher Questions Solution Bank Rumusan Jawapan SPM & IGCSE Questions Answers Solution


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Answer ( 1 )


    6. a) i) -Touching hot pan (stimulus).

    -Afferent neuron senses this, sends nerve impulses to the spinal cord where interneurons are located. Information gets integrated.

    -Interneurons send nerve impulses to the efferent neurons.

    -Efferent neurons signals the effector (muscle tissue in the hand). Hand pulls away from hot pan.


    Afferent neuron Efferent neuron
    Also called sensory neurons Also called motor neurons 
    Cell body located at the side Cell body located at the start of the neuron
    Has receptor to detect stimuli Does not have receptor 
    Sends nerve impulses from sensors to interneurons located in the CNS  Transmits signals from interneurons (CNS) to effectors 
    Short axon  Long axon
    Found in sensory organs like skin, tongue, nose Found in muscles or glands


    b) -Under normal conditions, nerve impulse triggers the release of neurotransmitters from synaptic vesicles in the presynaptic terminal.

    -The neurotransmitters cross the synaptic cleft and binds to receptors on the postsynaptic membrane. Generation of nerve impulses. Get transmission for anxiety feeling.

    -Drugs like depressants inhibit the activity of the CNS.

    -Drugs reduce the amount of neurotransmitters being released. Lesser amount of neurotransmitters binding to receptors. Get a reduction in the transmission of nerve impulses. Decreases feeling of anxiety.

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