Answer the following
Qs 1. What is required to prove that
a). Light is necessary for photosynthesis? ( Paper)
b). Chlorophyll is necessary for photosynthesis ? (Kind of Plant)
Qs 2 Which solution is used to test starch ?
Reasoning :
Qs 3. Why is the leaf boiled in alcohol?
Qs 4. Why the alcohol is kept in a beaker of water?
Qs.5. Why the plant is kept in dark for two days before performing any experiment on photosynthesis ?
Hots
Qs 6. What will happen if all green plants of a particular area are cut off?
Qs 7. Explain how carbon di oxide and oxygen balance is maintained in the environment ?
Answers
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To test leaves for the presence of starch,the leaf is boiled in water and then the boiled leaf is placed in a boiling tube containing 90% ethanol (ethyl alcohol). The ethanol boils and the green colouring (chlorophyll) is removed from the leaf. The iodine reagent is then added, which causes the green areas on the leaf, where starch is supposedly present, to turn to a blue-black colour. This indicates the presence of starch in the leaf.
To test leaves for the presence of starch,the leaf is boiled in water and then the boiled leaf is placed in a boiling tube containing 90% ethanol (ethyl alcohol). The ethanol boils and the green colouring (chlorophyll) is removed from the leaf. The iodine reagent is then added, which causes the green areas on the leaf, where starch is supposedly present, to turn to a blue-black colour. This indicates the presence of starch in the leaf. Hence, the correct statement is: The solvent used to dissolve the chlorophyll pigments while testing a leaf for starch is alcohol.
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