Deoxyribonucleic acid (DNA) is the molecule that contains genetic information. DNA is encoded through a combination of nucleotides that bind together in a specific double helix pattern.

Decomposers (saprotrophs) are organisms such as bacteria and fungi that break down the organic matter in the dead bodies of plants and animals into simple nutrients.

An ecosystem is a biological community of interacting organisms and their physical environment. This includes both the biotic (living) and abiotic (non-living).

The rate of vibration of sound is called frequency and is measured in hertz (Hz). One hertz is one repetition per second and sounds with high frequency have a higher pitch than sounds with lower frequency. Humans can hear sounds in the range of 20 Hz to 20 kHz.

Digestion begins in the mouth where the teeth and tongue break down food mechanically through chewing and saliva, via the enzyme salivary amylase, starts to break starches down chemically. From the mouth, food travels down the esophagus where contractions push the food into the stomach.