The presence of hydrogen bond is one factor that explains the fact that ice floats over water because it has less density.
Due to this, rivers and lakes freeze from the surface whereas it is in liquid state at the bottom which allows the sea animals to survive even in colder temperatures.
Water makes up at least 70% of earth and 65% of our bodies and this property of water is essential for our lives as it maintains the survival.
This is just an educated guess. As the purple pigment, caused by anthocyanins, are on the bottom side of the plant, their purpose could probably be to direct the light.
Specifically, a purple pigment on the bottom of the plant would absorb certain wavelengths near the purple spectrum, and reflect other wavelengths back toward the portion of the plant with chlorophyll. In this way, light does not simply pass through the leaf, instead it is reflected back in towards the chlorophyll to maximize the amount of light being used for photosynthesis.
Al3+ represents aluminium ions
Hey! they are usually single celled!
hope this helped xoxo