Question

describe an activity to show that sunlight is necessary for photosynthesis

Answer 1

KEEP A POTTED PLANT IN LIGHT FOR 2 DAYS.
KEEP ANOTHER POTTED PLANT IN DARK FOR 2 DAYS.
TEST THEM AFTER THAT FOR STARCH(PRODUCED DURING PHOTOSYNTHESIS)

THE POTTED PLANT KEPT IN LIGHT GIVES A +VE STARCH TEST.
THE POTTED PLANT KEPT IN DARK GIVES A -VE STARCH TEST.

THEREFORE SUNLIGHT IS NECESSARY FOR PHOTOSYNTHESIS.
HENCE PROVED.

Answer 2

$\huge{\boxed{Activity\:!!}}$

$\large\bf\red{Requirements\::-}$Destarched Potted Plant, Black Paper, Iodine, Alcohol, water, beaker, tripod stand, wire gauze, burner or spirit lamp, clips.

⇏A Plant can be Destarched by keeping in dark for 48Hrs. Destarching (to remove the present starch) can also be carried out by wrapping the leaves in Black Paper or aluminum foil for 2-3 Days.

$\large\bf\blue{Method\::-}$

• Cover the upper surface of leaf with black paper having a design cut on it.

•Clip the paper firmly with the leaf.

• Keep this potted plant in the sunlight for 6-8 Hrs.

•Remove the leaf and out it in alcohol in the beaker. Don't boil the alcohol in a beaker directly on the Burner. Boil By Keeping the beaker having alcohol and leaf, in another breaker containing water.

↪This Process removes the Chlorophyll and lead turns pale. Take out the leaf and wash it in water. Spread the leaf on slide or watch glass. Put few drops of iodine solution on the leaf.

$\large\bf\orange{Observation\::-}$

Leaf turns blue-black in the cut design area on the leaf. Remaining part of the leaf remains in brown in colour.

$\large\bf\green{Conclusion\::-}$$<font color="blue"><b>$

Food (starch) is formed only in exposed part of leaf to Sunlight.✔✔