WORKSHEET
CHAPTER -1( NUTRITION IN PLANTS)
Q1.
Observe the experiment and answer the following questions:
Blue-black
Boiling
water
Water
Alcohol
Leaf boiled
in water
Leaf transferred in a test
tube containing alcohol
Step 3
Gently heat waterto
make alcohol bol
Step 4
Leaf washed
in tap water
Step 5
Drops of
solution adder
Step 6
Step 1
Step 2
(a) What does the above experiment prove?
(b) Name the solution used for the test.
(c) What is the substance stored by the plant's leaf?
Answers
Answer:
Explanation:
A positive test for starch in a leaf provides evidence that photosynthesis has occurred by the formation of violet black colour in the presence of iodine solution.
Collection of green leaf and exposed them to sunlight for a few hours
Heat the 250cm
3
water until it boils. Keep the water at boiling point.
Place the leaf in the boiling water with the help of forceps and boil for 2 minutes.
Turn off the Bunsen Burner. (If you are using a heat source without a naked flame - electric water bath or hot plate - this step is unnecessary.)
Place the boiled leaf in a boiling tube containing 90% ethanol.
Place the boiling tube in hot water and boil for 10 minutes or until the leaf decolorizes. (It may be necessary to replace the ethanol.)
Gently remove the leaf and wash with a fine trickle of cold tap water.
Spread the leaf evenly on a white tile.
Add a few drops of iodine/potassium iodide solution to the leaf and note any observations.
Answer:
a startch is present in leaves
b methylated spirit
c startch