A cell is the basic unit of life.

The cell is the smallest structure that can live and reproduce.

Cells grow and develop, reproduce and interact with the environment.

Photosynthesis is one of the most important biological processes.

It allows plants to capture and use light as an energy source.

Photosynthesis is the process of converting light energy into chemical energy.

A virus is a small biological structure that attacks and enters cells.

Once inside a cell, a virus reproduces and makes many copies of itself.

Some diseases such as influenza are viruses.

Bacteria are one-celled forms of life that are all around us.

Although they have a single-cell structure, they are very important.

Many bacteria are inside us, and help us digest our food.

DNA is a complex molecule that stores information and can make copies of itself.

Nearly every cell in a person's body has the same DNA.

The information stored in DNA tells cells what to do, and is necessary for reproduction.

(There are billions of bacteria in our intestines.)

(The influenza virus spreads through the air when people cough or sneeze.)