â¢ SEMICOLON (noun) The noun SEMICOLON has 1 sense: 1. a punctuation mark (';') used to connect independent clauses; indicates a closer relation than does a period. Familiarity information: SEMICOLON used as a noun is very rare.
Cells are the building blocks of life. All living organisms are made up of cells. The cells were discovered by Robert Hooke in 1665. In the human body there are about 100 trillion to 1014 cells. hey are made up of a single cell. O rganisms like the amoeba, P aramecium are single-celled organisms, they are the oldest forms of life, they existed about 3.8 million years ago. Bacteria, a rchaea, protozoa, unicellular algae and un i cellular fungi are the main groups of unicellular organisms.
Living organisms are composed primarily of carbon, oxygen, and hydrogen. Other elements in living matter include calcium, nitrogen, phosphorus, potassium, and trace amounts of other elements. Water is made up of hydrogen and oxygen. The oceans also contain salt, made up of sodium and chlorine. The atmosphere is mostly made up of the element nitrogen, existing in diatomic form (N2). It also includes oxygen, carbon (in carbon dioxide) and a small amount of other elements.