Let’s explain the answer with an experiment. For the experiment , we need 4 cups , a black cloth , some cotton and some seeds( preferably pea seeds) and some water. Lets put some seeds in the first cup and keep it under sunlight. In the second cup ,take the cotton and dip it in water and place it inside the cup do the same on the third cup . Fourth cup must be a transparent cup put the same water dipped cotton inside the cup. Put the seeds and close it air tighted. Take the third cup and place it in some dark place without any sunlight . Leave the cups for a week. After one or two weeks lets check the growth. The results will be amazing . The first cup doesn’t show any progress. But in other cups the seed may have sprouted in varying levels . Air tight container would show very low progress. The necessity of air, water and sunlight in the growth of plants is explained. Only with necessary water availability , plants can transport nutrients for their growth. In some desert regions plants like cactus would store water inside their body for survival. Water is an important stuff which regulates and causes growth of the plant.