SPM Biology 2014

Question

5 . Diagram 5.1 shows the conditions of the thoraz during processes J and K in breathing mechanism.

Rajah 5.1 menunjukkan keadaan toraks semasa proses J dan proses K dalam mekanisme pernafasan.

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(a)(i) Name the process J and K.

Namakan proses J dan proses K.

(ii) State three differences between processes J and K.

Nyatakan tiga perbezaan anatara proses K dan proses K.

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(b) Breathing is an involuntary process controlled by the respiratory centre in medula oblongata. Describe what happens to the rate of respiration of a climber at the peak of a mountain.

Pernafasan adalah proses laur kawal yang dikawal oleh pusat pernafasan dalam medula oblongata. Jelaskan apa yang berlaku kepada kadar pernafasan bagi seorang pendaki apabila berada di puncak gunung yang tinggi.

 

(c) An athlete experiences muscle cramp during a 100 metre sprint. Explain how the activity causes muscle cramp.

Seorang atlet mengalami kekejangan otot semasa larian pecut 100 meter. Terangkan bagaimana aktiviti tersebut menyebabkan kekejangan otot.

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Answer ( 1 )

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    2021-02-25T16:46:15+08:00

    5.a)i)J:inhalation

    K:exhalation

    ii)

    Process J Process K
    Rib cage will move outwards and upwards  Rib cage will move inwards and downwards 
    Diaphragm contracts and flattens Diaphragm relaxes
    External intercostal muscles will contract External intercostal muscles will relax

     

    b)-At the peak of the mountain there would be a lower concentration of oxygen.

    -This is detected by the peripheral chemoreceptors found in the carotid and aortic bodies.

    -These chemoreceptors send signals to the respiratory control centre which then sends nerve impulses to the effectors, diaphragm and intercostal muscles. The effectors are stimulated to contract and relax at a quicker rate.

    -Ventilation and breathing rate quickens, subsequently rate of respiration increases.

     

    c)-Initially, the muscles were undergoing aerobic respiration. Then, oxygen consumption by muscles becomes much greater than the oxygen supplied by blood.

    -Thus this create an oxygen deficit (oxygen debt). The muscle would then have to switch to anaerobic respiration to obtain energy.

    -However, during anaerobic respiration glucose partially breakdown to form lactic acid.

    -When lactic acid accumulates it causes muscle cramps to occur.

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