Which process is demonstrated when a leafy twig of a sub-tropical plant is immersed in water?

When strips of cobalt chloride paper are placed on either side of a dorsiventral leaf,why do the strips on the lower side become pink more speedily?

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?

Stomatal index $(I)$ is equal to:

In some plants,the leaves drop down during the day while becoming normal during the night.

How the change in $pH$ occurs in guard cells was explained and the theory of starch $\rightleftharpoons$ sugar interconversion was proposed by: