Which of the following is called a necessary evil?

By which process is water lost from the plants in the form of water droplets?

The theory of starch-glucose interconversion for stomatal opening and closing was proposed by:

If the rates of transpiration and water absorption of a flowering plant are measured over a period of $24$ hours,it is found that the rate of transpiration reaches its peak at about mid-day and then declines,whereas the peak for water absorption is reached approximately two hours later. Which one of the following statements provides the best explanation of these results?

If a piece of dry $COCl_2$ paper is placed on the lower epidermis of a leaf,the color changes from blue to pink because...

The trunk of a tree shrinks in the day due to