An atom is the smallest component of an element that still retains the properties of the element.

The biosphere is the global ecological system integrating all living beings and their relationships. This includes their interactions with the lithosphere (the rigid outer part of the earth, consisting of the crust and upper mantle), hydrosphere (all surface water), and atmosphere (the envelope of gases surrounding the planet).

Small quantities of certain minerals like iron, calcium, magnesium, and salt are important for nutrition and health.

Power is the rate at which work is performed or work per unit time: \(P = {w \over t}\) and is measured in watts (W).

Food is mixed with gastric acid and pepsin in the stomach to help break down protein.