تجارب علوم بسيطة لوحدة علوم الحياة , اكتشف الغذاء المخزن في ورقة النبات

في هذة التجربة سوف يكتشف الطالب من خلال تفاعل كيميائي بسيط وجود الغذاء المخزن في ورقة النبات لانه اثناء عملية البناء الضوئي يخزن النبات الغذاء في الأوراق وعند اضافة مادة الايودين سوف يكشف عن وجود النشا وهو الغذاء المخزن ويضهر باللون البنفسجي

الترجمة بالمرفقات

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Leaf Food

Biology

Things You Will Need

Pale green leaf
Tincture of iodine
Rubbing alcohol
Shallow dish
Pint jar with a lid
Eyedropper
Paper towels

Do This

Fill the jar about one-half full with rubbing alcohol.
Place the pale green leaf in the jar of alcohol and close with the lid. The paler the leaf, the easier it is to remove the green pigment.
Let the jar stand undisturbed for 24 hours.
Remove the leaf and dry it by blotting with a paper towel.
Place the leaf in a shallow dish.
Use the eyedropper to cover the surface of the leaf with iodine.

What Should Have Happened

Dark areas appear on the leaf. Starch is produced in the leaf by a chemical reaction called photosynthesis. Starch is a food substance that produces energy. The alcohol removes the waxy coating on the leaf and some of the green pigment, chlorophyll. It is easier to test for starch in a leaf once the waxy coating and green chlorophyll are removed. Iodine chemically reacts with the starch to form a dark purple to black color. The dark areas that appeared on the leaf indicate areas of starch in the leaf from photosynthesis

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