Answer:
nitrogen fixation is the answer
Molecules are moving because they have energy. As the liquid cools down, the amount of energy is reduced and the molecules start to move slower. When the water temperature reaches around 0°C, the molecules stick together and form a solid – ice. Even in this solid stage, the molecules are still moving – we just can’t see it.
Ophthalmology is the specialty dealing with disorders and injuries of the eye... And ophthalmologist is the specialist responsible. Do not confuse with a optometrist. An optometrist only does basic diagnosis and fitting for eye ware.
Many cacti have roots that spread out widely, but only penetrate a short distance into the soil. In one case, a young saguaro only 12 cm (4.7 in) tall had a root system with a diameter of 2 m (7 ft), but no more than 10 cm (4 in) deep.
In other words they can't penetrate that deep.
