viewai 發問於 科學及數學生物學 · 1 十年前

M.C. about homeostasis

In a mammal, the water concentration of certain body fluids must be kept more or less constant. Which of the following belong(s) to this category?

(1) sweat

(2) tissue fluid

(3) blood plasma

(4) urine

A. (1) & (2) only

B. (1) & (4) only

C. (2) & (3) only

D. (2), (3), (4) only

1 個解答

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  • 1 十年前
    最愛解答

    C. (2) & (3) only

    首先.. (4) urine 一定唔係.. 因為 homeostasis 入面提到..

    飲得多水就會排走多 d urine.. 會 dilute d..

    飲得少水就會排走少 d urine.. 會 concentrate d..

    呢一點就証明 urine 既 water concentration 唔會 keep 住o係一樣..

    當冇左 (4) 之後.. 答案得番 A 同 C.. 因為 A 同 C 都有 (2)..

    即係 tissue fluid 一定係答案.. 宜家要諗既係 (1) 同 (3) 邊個o岩..

    (1) 係 sweat.. sweat 既water potential 同你身體既 mineral 多少有關..

    多 mineral.. water concentration 就會低..

    少 mineral.. water concentration 就會高..

    用消除法就可以知道答案係 (2) 同 (3) 喇..

    而且諗下.. (1) 同 (4) 都係 waste.. 其實身體都唔要呢 d waste..

    所以唔會好似題目咁講 "must be kept more or less constant"

    (2) 同 (3) 都係身體好重要既一部分~ 並唔係 waste.. 所以就要 keep.

    不過點解 (2) 要 keep constant 呢?

    tissue fluid 既 concentration 係會影響到 cytoplasm..

    cytoplasm 係唔會成日變的..

    (3) 要 keep 既原因係如果 water concentration 一變..

    body cell 就有機會吸唔到水.. 吸唔到既話..

    好多polar 既 material 都吸唔到.. 對身體做成影響..

    最後得出既結論就係 C. (2) & (3) only

    資料來源: 應屆高考生
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