How are Mistletoe and Rhizobium different from each other? Explain? 

Give a reason for the following statement:
A potted plant was kept in the dark for two days. After that, a stalk of leaves was taken from the plant. It was then placed in a bell jar containing a mixture of gases X and Y in equal volumes. This experiment set up was exposed to bright light for a period of time. Give reason how the volume of gas X decreased while the volume of gas Y increased. How will the leaves show the result when tested with Iodine solution?