Plants exhibit phototropism because long roots plants absorb more water and nutrients they need the sun's energy in order to produce food water is essential to a plant's growth strong stems are more wind resistant

they need the Sun's energy in order to produce food
There are several starting ingredients that are required for starting the process of photosynthesis. The most important are sunlight, water, carbon dioxide and certain minerals. Sunlight helps in building up the optimum temperature that is required to start the process of photosynthesis. Water is an important raw material that helps to absorb the carbon dioxide from the air. It also directly influences the opening and closing of the stomata. Carbon dioxide on the other hand is one of the most important raw material that helps to make glucose via the process of photosynthesis.

Gas will most likely  fill the container