Question

A plant was kept in the dark for two to three days and then was shifted into bright
light for five hours. However, the plant was deprived of carbon dioxide. Which of the
following will be the observation if a leaf from this plant is tested for the presence of starch?

i. Only the upper surface of the leaf will turn blue-black in colour

ii. The entire leaf will turn blue-black in colour

iii. The leaf will not turn blue-black in colour

iv. Only the lower surface of the leaf will turn blue-black in colour

Please answer the question it's very urgent.​

Answer 1

Answer:

Explanation:

the leaf will not turn blue back

Answer 2

Answer:

Plants need light, CO², chlorophyll and water to produce starch through photosynthesis. If the leaf will contain starch, it will turn blue-black showing that it has performed photosynthesis. If the plant lacks starch, it will show yellow colour.

If a plant is placed in complete dark for two to three days, it will lack starch and will eventually die. Hence, the leaf will not turn blue-black in colour and will be yellow. (Option - iii)