Which of the following is the significance of transpiration?

Guard cells are helpful in:

Cuticular transpiration occurs 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?

Which of the following conditions may be favourable for the wide opening of stomata?

In which of the following situations does stomatal transpiration exhibit a steep decline?