Which of the structures in this figure is the backbone of a steroid?

Olive oil is a

Why is ATP is necessary for all living things?

Nitrogen gas (N2) is composed of two nitrogen atoms joined by a triple covalent bond.  How many electrons are shared between the two atoms?

Hydrocarbons

The level of biological organization that can be defined as “all the ecosystems on earth” is the

Certain substances behave like bank accounts for H+ ions because they can absorb excess H+ ions to keep a solution from becoming too acidic and release H+ ions to keep the solution from becoming too basic. Such molecules are called

Why is ATP is necessary for all living things?

DNA is a

The smallest unit of life that retains all (or most) of the basic characteristics associated with living organisms, such as the ability to reproduce, respond to stimulus, and metabolize energy, is the