Cotton is a

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

DNA is a

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?