Question

A variegated leaf with green and yellow paths is used for an experiment to prove that chlorophyll is required for photosynthesis. Before the experiment, the green portions (A), and the pale yellow portions (B), are observed. What will be the color of ′A′ just before and after the starch test? Also, write the equation of photosynthesis and mark well as validate from which molecule the by-product is obtained.

Answer 1

Hint: When iodine is reacted with the starch, it gives a blue-black color. The starch is present in the parts of the plant and when iodine is applied to it, it turns to a blue-black color.

Complete answer:
It was observed in the experiment that the color of A i.e. the green portion before the starch test is performed is found to be pale yellow because chlorophyll needs to be removed before performing the starch test, and after the test, it's color changes to blue-black because of the reaction of iodine and starch present in A.

Balanced Equation Of photosynthesis is given below:
$6C{O}_2+6H_{2}O+LightEnergy\to C_6{H}_{12}{O}_6+6O_2$.
In photosynthesis, the water molecules split into protons ($H^{+}$) electrons, and oxygen gas.

Additional Information: The inner part of the leaf turns blue-black on adding iodine solution which was originally green and shows that starch is present in the inner part of the leaf. Through this observation, we can conclude that photosynthesis takes place in the presence of chlorophyll to make starch. sunlight is the most important factor for photosynthesis as the rate of photosynthesis depends upon the quantity and quality of light. As we know that photosynthesis is performed In a different manner by different species, the process always starts when energy from light is absorbed by proteins called reaction centers that contain green chlorophyll pigments. In plants, these proteins are held inside organelles called chloroplasts, which are most abundant in leaf cells, while in bacteria they're embedded within the plasma membrane of the cell.

Note: It is very important to note that to make one molecule of glucose during photosynthesis by plants, it takes 6 molecules of the water and six molecules of carbon dioxide. In 1814, J.J. Colin, H.F. Gaultier, and F. Stromeyer were the first to describe the starch-iodine test.