Form2 Science 急！！！20點

[匿名]

2015-03-18 8:41 am

Use iodine solution to test starch in leaf.
有關test 嘅詳情麻煩去wiki唔該曬:)
問題來了
1)Why is it necessary to put the test tube that contains alcohol into a beaker of hot water but not to directly with a Bunsen burner?
2)If the plant has to be destarched before the experiment,how and why?

回答 (1)

MintyB

2015-03-18 7:44 pm

✔ 最佳答案

1) Alcohol is highly flammable and harmful. The risks in this procedure are reduced by using hot water in a beaker rather than heating with a Bunsen burner flame.
2)
HOW TO DESTARCH?
Keep the plant in dark for 24-48 hours, so that the plant will use up the starch.
WHY DESTARCH A PLANT?
To investigate whether a factor is needed for photosynthesis, will be determined by looking at starch production. Therefore we need to destarch the plant/leaf before the experiment. If starch is found after the experiment, that means the photosynthesis has occurred in the presence of the factor.

參考: http://brilliantbiologystudent.weebly.com/why-de-starch-a-plant.html

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