Question

Test for starch in leaves

Answer 1

Starch:

1. Starch is a white, powdered material made mostly of glucose that is used as sustenance by plants.
2. The synthesis of starch occurs by a biological process known as photosynthesis.
3. The existence of starch within leaves is sufficient proof that photosynthesis occurs in leaves.

Test:

Required materials: Plant, glass beaker, solution of iodine, saucepan, ethyl alcohol, tweezers, and a stove.

Method:

1. Pour a beaker with alcohol and set it in a pan full of water for 24 hours.
2. Continue to heat the pan till ethyl alcohol starts boiling, then switch off the flame.
3. Soak each of leaves in boiled water for minute using tweezers.
4. Put the leaves in jar containing ethyl alcohol (120 seconds) till they turn practically white.
5. Put one in a small dish for each of them.
6. Apply a few drops of iodine solution to these leaves and observe.

Observation:

1. The chlorophyll is broken down by alcohol, and the leaf is killed by hot water. As a result, the leaf is not green.
2. Attributed to the prevalence of starch with iodine as an indicator, when leaves were treated with iodine, one gets convert to blue-black.
3. The color of the opposite leaf converts into a reddish-brown color.
4. The leaf that has been exposed to light turns blue-black, suggesting that it has been undergoing photosynthesis and making starch.